Die Anleitung zu Java Hibernate

1-  Database vorbereiten

Hibernate ist ursprunglich eine Bibliothek, die zur Arbeit mit allen DB Typen geboren wird. Es ist unabhängig von einem DB Typ, das Sie gewählt haben. Wenn  Java   "Einmal schreiben, überall laufen" ist, ist Hibernate dann  "Einmal schreiben, auf allen DB Typen laufen"
In diesem Artikel verwende ich simplehr, das eine einfache Database ist und in vielen Anleitungen in o7planning verwendet wird. Sie können es mit einer der Database  Oracle, MySQL oder  SQL Server erstellen. Sehen Sie die folgende Anleitung:

2-  Maven Project erstellen und die Bibliothek anmelden

Hier erstelle ich ein Projekt  Maven , und melde ich die Bibliothek  Hibernate in  pom.xml ​​​​​​​an.
  • File/New/Other...
Project is created.
In  pom.xml melde ich die Bibliothek  Hibernate 5, und die Bibliothek JDBC für die unterschiedlichen Database  Oracle, MySQL und  SQL Server.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
               http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.o7planning</groupId>
    <artifactId>HibernateTutorial</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>HibernateTutorial</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>


    <repositories>
        <!-- Repository for ORACLE JDBC Driver -->
        <repository>
            <id>codelds</id>
            <url>https://code.lds.org/nexus/content/groups/main-repo</url>
        </repository>
    </repositories>
   
   
    <dependencies>


        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <!-- Hibernate Core -->
        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.2.2.Final</version>
        </dependency>


        <!-- MySQL JDBC driver -->
        <!-- http://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.34</version>
        </dependency>

        <!-- Oracle JDBC driver -->
        <dependency>
            <groupId>com.oracle</groupId>
            <artifactId>ojdbc6</artifactId>
            <version>11.2.0.3</version>
        </dependency>

        <!-- SQLServer JDBC driver (JTDS) -->
        <!-- http://mvnrepository.com/artifact/net.sourceforge.jtds/jtds -->
        <dependency>
            <groupId>net.sourceforge.jtds</groupId>
            <artifactId>jtds</artifactId>
            <version>1.3.1</version>
        </dependency>

    </dependencies>
   
</project>

 

3- Die Klassen Entity

Wir erstellen die Klassen  Entity. Jeder  Entity vertritt eine Tabelle in  DB. Sagen wir die Dinge in dieser Klasse nicht.
  1. Department - Die Abteilung
  2. Employee - Der Mitarbeiter
  3. SalaryGrade -Lohn-Stufe
  4. Timekeeper - Der Zeitnehmer.
Department.java
package org.o7planning.tutorial.hibernate.entities;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;

@Entity
@Table(name = "DEPARTMENT",
  uniqueConstraints = { @UniqueConstraint(columnNames = { "DEPT_NO" }) })
public class Department {

private Integer deptId;
private String deptNo;

private String deptName;
private String location;
private Set<Employee> employees = new HashSet<Employee>(0);

public Department() {
}

public Department(Integer deptId, String deptName, String location) {
   this.deptId = deptId;
   this.deptNo = "D" + this.deptId;
   this.deptName = deptName;
   this.location = location;
}

@Id
@Column(name = "DEPT_ID")
public Integer getDeptId() {
   return deptId;
}

public void setDeptId(Integer deptId) {
   this.deptId = deptId;
}

@Column(name = "DEPT_NO", length = 20, nullable = false)
public String getDeptNo() {
   return deptNo;
}

public void setDeptNo(String deptNo) {
   this.deptNo = deptNo;
}

@Column(name = "DEPT_NAME", nullable = false)
public String getDeptName() {
   return deptName;
}

public void setDeptName(String deptName) {
   this.deptName = deptName;
}

@Column(name = "LOCATION")
public String getLocation() {
   return location;
}

public void setLocation(String location) {
   this.location = location;
}

@OneToMany(fetch = FetchType.LAZY, mappedBy = "department")
public Set<Employee> getEmployees() {
   return employees;
}

public void setEmployees(Set<Employee> employees) {
   this.employees = employees;
}
}
Employee.java
package org.o7planning.tutorial.hibernate.entities;

import java.util.Date;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.Lob;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.UniqueConstraint;

@Entity
@Table(name = "EMPLOYEE",
   uniqueConstraints = { @UniqueConstraint(columnNames = { "EMP_NO" }) })
public class Employee {
private Long empId;
private String empNo;

private String empName;
private String job;
private Employee manager;
private Date hideDate;
private Float salary;
private byte[] image;

private Department department;
private Set<Employee> employees = new HashSet<Employee>(0);

public Employee() {
}

public Employee(Long empId, String empName, String job, Employee manager,
        Date hideDate, Float salary, Float comm, Department department) {
    this.empId = empId;
    this.empNo = "E" + this.empId;
    this.empName = empName;
    this.job = job;
    this.manager = manager;
    this.hideDate = hideDate;
    this.salary = salary;
    this.department = department;
}

@Id
@Column(name = "EMP_ID")
public Long getEmpId() {
    return empId;
}

public void setEmpId(Long empId) {
    this.empId = empId;
}

@Column(name = "EMP_NO", length = 20, nullable = false)
public String getEmpNo() {
    return empNo;
}

public void setEmpNo(String empNo) {
    this.empNo = empNo;
}

@Column(name = "EMP_NAME", length = 50, nullable = false)
public String getEmpName() {
    return empName;
}

public void setEmpName(String empName) {
    this.empName = empName;
}

@Column(name = "JOB", length = 30, nullable = false)
public String getJob() {
    return job;
}

public void setJob(String job) {
    this.job = job;
}

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "MNG_ID")
public Employee getManager() {
    return manager;
}

public void setManager(Employee manager) {
    this.manager = manager;
}

@Column(name = "HIRE_DATE", nullable = false)
@Temporal(TemporalType.DATE)
public Date getHideDate() {
    return hideDate;
}

public void setHideDate(Date hideDate) {
    this.hideDate = hideDate;
}

@Column(name = "SALARY", nullable = false)
public Float getSalary() {
    return salary;
}

public void setSalary(Float salary) {
    this.salary = salary;
}

@Column(name = "IMAGE", length = 1111111, nullable = true)
@Lob
public byte[] getImage() {
    return image;
}

public void setImage(byte[] image) {
    this.image = image;
}

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "DEPT_ID", nullable = false)
public Department getDepartment() {
    return department;
}

public void setDepartment(Department department) {
    this.department = department;
}

@OneToMany(fetch = FetchType.LAZY, mappedBy = "empId")
public Set<Employee> getEmployees() {
    return employees;
}

public void setEmployees(Set<Employee> employees) {
    this.employees = employees;
}

}
SalaryGrade.java
package org.o7planning.tutorial.hibernate.entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "SALARY_GRADE")
public class SalaryGrade {
 private Integer grade;
 private Float lowSalary;
 private Float highSalary;

 public SalaryGrade() {
 }

 public SalaryGrade(Integer grade, Float lowSalary, Float highSalary) {
     this.grade = grade;
     this.lowSalary = lowSalary;
     this.highSalary = highSalary;
 }

 @Id
 @Column(name = "GRADE")
 public Integer getGrade() {
     return grade;
 }

 public void setGrade(Integer grade) {
     this.grade = grade;
 }

 @Column(name = "LOW_SALARY", nullable = false)
 public Float getLowSalary() {
     return lowSalary;
 }

 public void setLowSalary(Float lowSalary) {
     this.lowSalary = lowSalary;
 }

 @Column(name = "HIGH_SALARY", nullable = false)
 public Float getHighSalary() {
     return highSalary;
 }

 public void setHighSalary(Float highSalary) {
     this.highSalary = highSalary;
 }
}
Timekeeper.java
package org.o7planning.tutorial.hibernate.entities;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

import org.hibernate.annotations.GenericGenerator;

@Entity
@Table(name = "TIMEKEEPER")
public class Timekeeper {
  public static final char IN = 'I';
  public static final char OUT = 'O';

  private String timekeeperId;

  private Date dateTime;

  private Employee employee;

  // 'I' or 'O'
  private char inOut;

  @Id
  @GeneratedValue(generator = "uuid")
  @GenericGenerator(name = "uuid", strategy = "uuid2")
  @Column(name = "Timekeeper_Id", length = 36)
  public String getTimekeeperId() {
      return timekeeperId;
  }

  public void setTimekeeperId(String timekeeperId) {
      this.timekeeperId = timekeeperId;
  }

  @Column(name = "Date_Time", nullable = false)
  @Temporal(TemporalType.TIMESTAMP)
  public Date getDateTime() {
      return dateTime;
  }

  public void setDateTime(Date dateTime) {
      this.dateTime = dateTime;
  }

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "EMP_ID", nullable = false)
  public Employee getEmployee() {
      return employee;
  }

  public void setEmployee(Employee employee) {
      this.employee = employee;
  }

  @Column(name = "In_Out", nullable = false, length = 1)
  public char getInOut() {
      return inOut;
  }

  public void setInOut(char inOut) {
      this.inOut = inOut;
  }

}

4-  Hibernate Konfiguration

Das Zweck ist, dass Hibernate   Database lesen kann sowie die Liste der  Entity , die Sie in den vorherigen Schritt erstellt haben, anmelden
Die File  hibernate.cfg.xml Konfiguration wird in  src/main/java lokalisiert.
hibernate.cfg.xml (ORACLE)
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                          "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
 <session-factory>

     <property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
     <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
     <property name="hibernate.connection.url">jdbc:oracle:thin:@localhost:1521:db11g</property>
     <property name="hibernate.connection.username">simplehr</property>
     <property name="hibernate.connection.password">12345</property>
     <property name="hibernate.show_sql">true</property>
     <property name="hibernate.connection.release_mode">auto</property>
     <property name="current_session_context_class">thread</property>
     <property name="hibernate.connection.autoReconnect">true</property>


     <mapping class="org.o7planning.tutorial.hibernate.entities.Department" />
     <mapping class="org.o7planning.tutorial.hibernate.entities.Employee" />
     <mapping class="org.o7planning.tutorial.hibernate.entities.SalaryGrade" />
     <mapping class="org.o7planning.tutorial.hibernate.entities.Timekeeper" />

 </session-factory>

</hibernate-configuration>
hibernate.cfg.xml (MySQL)
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

  <session-factory>
      <!-- Database connection settings -->
      <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
      <property name="connection.url">jdbc:mysql://tran-vmware:3306/simplehr?serverTimezone=UTC</property>
      <property name="connection.username">root</property>
      <property name="connection.password">1234</property>

      <!-- JDBC connection pool (use the built-in) -->
      <property name="connection.pool_size">1</property>

      <!-- SQL dialect -->
      <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

      <!-- Enable Hibernate's automatic session context management -->
      <property name="current_session_context_class">thread</property>

      <!-- Disable the second-level cache -->
      <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

      <!-- Echo all executed SQL to stdout -->
      <property name="show_sql">true</property>

      <mapping class="org.o7planning.tutorial.hibernate.entities.Department" />
      <mapping class="org.o7planning.tutorial.hibernate.entities.Employee" />
      <mapping class="org.o7planning.tutorial.hibernate.entities.SalaryGrade" />
      <mapping class="org.o7planning.tutorial.hibernate.entities.Timekeeper" />

  </session-factory>

</hibernate-configuration>
hibernate.cfg.xml (SQL Server)
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
      "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
      "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <!-- Database connection settings -->
        <property name="connection.driver_class">net.sourceforge.jtds.jdbc.Driver</property>
        <property name="connection.url">jdbc:jtds:sqlserver://localhost:1433/simplehr;instance=SQLEXPRESS</property>
        <property name="connection.username">sa</property>
        <property name="connection.password">1234</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.SQLServerDialect</property>

        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>

        <!-- Disable the second-level cache -->
        <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>

        <mapping class="org.o7planning.tutorial.hibernate.entities.Department" />
        <mapping class="org.o7planning.tutorial.hibernate.entities.Employee" />
        <mapping class="org.o7planning.tutorial.hibernate.entities.SalaryGrade" />
        <mapping class="org.o7planning.tutorial.hibernate.entities.Timekeeper" />

    </session-factory>
</hibernate-configuration>
Jede Database hat eine unterschiedliche Dialect 
Zum Beispiel:
Dialect für  Oracle:
  • org.hibernate.dialect.Oracle10gDialect (Oracle 10g &11g)
  • org.hibernate.dialect.Oracle12cDialect
Dialect für  SQL Server:
  • org.hibernate.dialect.SQLServerDialect
  • org.hibernate.dialect.SQLServer2012Dialect
  • org.hibernate.dialect.SQLServer2008Dialect
Dialect für  MySQL:
  • org.hibernate.dialect.MySQLDialect
  • org.hibernate.dialect.MySQL5Dialect
Achtung: org.hibernate.dialect.Oracle10gDialect wird für O racle 10g, 11g, 12c ​​​​​​​benutzt.

Was ist Dialect ?

Dialect ist eine Klasse, die Hibernate sagt, wie die DatenTypen von Database zur die Datentypen vom Java und umgekehrt umzuwandeln. Gleichzeitig wird es benutzt um die Umwandlung zwischen die Funktionen von  HSQL ( Hibernate SQL) zur entsprechenden Funktionen von  Database zu definieren.
Java SQL Type Oracle My SQL SQL Server
Types.BIT number(1,0) bit bit
Types.BIGINT number(19,0) bigint bigint
Types.DATE date date date
 .......      
Types.CLOB clob longtext varchar(MAX)
Types.BLOB blob longblob varbinary(MAX)

5- SessionFactory

HibernateUtils ist eine Utility Klasse. Es hat ein Method für die Zurückgabe des Objekt SessionFactory. Die Klasse wird regelmäßig in die Beispiele verwendet.
HibernateUtils.java
package org.o7planning.tutorial.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.service.ServiceRegistry;

public class HibernateUtils {

    private static final SessionFactory sessionFactory = buildSessionFactory();

    // Hibernate 5:
    private static SessionFactory buildSessionFactory() {
        try {
            // Create the ServiceRegistry from hibernate.cfg.xml
            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()//
                    .configure("hibernate.cfg.xml").build();

            // Create a metadata sources using the specified service registry.
            Metadata metadata = new MetadataSources(serviceRegistry).getMetadataBuilder().build();

            return metadata.getSessionFactoryBuilder().build();
        } catch (Throwable ex) {
        
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static void shutdown() {
        // Close caches and connection pools
        getSessionFactory().close();
    }

}

6- Hibernate Query Language (HQL)

Hibernate benutzt die Sprache Hibernate Query Language ( HQL) um die Daten abzufragen (query). HQL hat einen kleinen Unterschied mit  SQL, das Sie kennen.

SQL:

  •  Die Daten auf die Tabelle  abfragen (query)

HQL:

  • die Daten auf die Klassen Entity abfragen (query).
-- SQL
-- This is a SQL query in table DEPARTMENT.
Select d.DEPT_NO, d.DEPT_NAME from DEPARTMENT d;

-- HQL
-- This is a HQL query in Entity Department.
Select d.deptNo, d.deptName from Department d;

-- Query Object
Select d from Department d;

The rules of operation of Hibernate:

Ihre Applikation, die die Commands  HQL während Runtime von Hibernate schreibt, kennt, dass sie mit welchem Database-Typ arbeitet. Sie wird die Command HQL zu dem den DB-Typ entsprechenden SQL wechseln. In der Praxis kennen wir, dass die Syntax SQL den kleinen Unterschied zwischen die verschiedenen Database-Typen hat. Und so sind die Daten-Typen.
Sie können die Syntax   HQL in ... referenzieren


7-  Hibernate die Daten abfragen

Es gibt viele Maßnahmen um die Daten in  Hibernate abzufragen. In diesem Part werde ich einige üblichen Maßnahme zum Daten-Abfragen vorstellen.

7.1- Die Objekt durch die Verwendung von HQL abfragen

Das ersten Beispiel:  HQL verwenden, die Objekt  Entity abzufragen
QueryObjectDemo.java
package org.o7planning.tutorial.hibernate.query;

import java.util.List;

import org.hibernate.query.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class QueryObjectDemo {

   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();

       try {
           
           // All the action with DB via Hibernate
           // must be located in one transaction.
           // Start Transaction.            
           session.getTransaction().begin();

   
           
           // Create an HQL statement, query the object.
           // Equivalent to the SQL statement:
           // Select e.* from EMPLOYEE e order by e.EMP_NAME, e.EMP_NO
           String sql = "Select e from " + Employee.class.getName() + " e "
                   + " order by e.empName, e.empNo ";

  
           // Create Query object.
           Query<Employee> query = session.createQuery(sql);

   
           // Execute query.
           List<Employee> employees = query.getResultList();

           for (Employee emp : employees) {
               System.out.println("Emp: " + emp.getEmpNo() + " : "
                       + emp.getEmpName());
           }
 
           // Commit data.
           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           // Rollback in case of an error occurred.
           session.getTransaction().rollback();
       }
   }
   
}
Das Ergebnis von der Durchführung des Beispiel

Demo2:

QueryObjectDemo2.java
package org.o7planning.tutorial.hibernate.query;

import java.util.List;

import org.hibernate.query.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class QueryObjectDemo2 {

    public static void main(String[] args) {
        SessionFactory factory = HibernateUtils.getSessionFactory();

        Session session = factory.getCurrentSession();

        try {

            // All the action with DB via Hibernate
            // must be located in one transaction
            // Start Transaction.                
            session.getTransaction().begin();
            
            // Create an HQL statement, query the object.
            // HQL with parameters.            
            // Equivalent to the SQL statement:
            // Select e.* from EMPLOYEE e cross join DEPARTMENT d
            // where e.DEPT_ID = d.DEPT_ID and d.DEPT_NO = :deptNo;        
            String sql = "Select e from " + Employee.class.getName() + " e "
                    + " where e.department.deptNo=:deptNo ";
 
            // Create query object.
            Query<Employee> query = session.createQuery(sql);

            query.setParameter("deptNo", "D10");

 
            // Execute query.
            List<Employee> employees = query.getResultList();

            for (Employee emp : employees) {
                System.out.println("Emp: " + emp.getEmpNo() + " : "
                        + emp.getEmpName());
            }
 
            // Commit data
            session.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            // Rollback in case of an error occurred.
            session.getTransaction().rollback();
        }
    }
}

7.2- Einige Säulen durch die Verwendung von HQL abfragen

QuerySomeColumnDemo.java
package org.o7planning.tutorial.hibernate.query;

import java.util.List;

import org.hibernate.query.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class QuerySomeColumnDemo {

    public static void main(String[] args) {
        SessionFactory factory = HibernateUtils.getSessionFactory();

        Session session = factory.getCurrentSession();

        try {
            session.getTransaction().begin();
 
            // Query some columns.
            String sql = "Select e.empId, e.empNo, e.empName from "
                    + Employee.class.getName() + " e ";

            Query<Object[]> query = session.createQuery(sql);
 
            // Execute Query.
            // Get the array of Object
            List<Object[]> datas = query.getResultList();

            for (Object[] emp : datas) {
                System.out.println("Emp Id: " + emp[0]);
                System.out.println(" Emp No: " + emp[1]);
                System.out.println(" Emp Name: " + emp[2]);
            }
 
            // Commit data.
            session.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            // Rollback in case of an error occurred.
            session.getTransaction().rollback();
        }
 
    }
}
 
Das Ergebnis der Durchführung des Beispiel:

7.3- Einige Säulen durch die Verwendung von HQL und JavaBean abfragen

Falls Sie die Daten in einigen Säulen auf einige Tabelle entnehmen brauchen, ist die Verwendung von  Java beans  die beste Maßnahme. Die Klasse  Java bean hat einen  constructor um die Werte ihrer Felder zu initialisieren.  Constructor nimmt an HQL Abfragen teil.
ShortEmpInfo.java
package org.o7planning.tutorial.hibernate.beans;

public class ShortEmpInfo {

    private Long empId;
    private String empNo;
    private String empName;

    //
    // Constructor have 3 parameters, will be used in the Hibernate Query.
    //
    public ShortEmpInfo(Long empId, String empNo, String empName) {
        this.empId = empId;
        this.empNo = empNo;
        this.empName = empName;
    }

    public Long getEmpId() {
        return empId;
    }

    public void setEmpId(Long empId) {
        this.empId = empId;
    }

    public String getEmpNo() {
        return empNo;
    }

    public void setEmpNo(String empNo) {
        this.empNo = empNo;
    }

    public String getEmpName() {
        return empName;
    }

    public void setEmpName(String empName) {
        this.empName = empName;
    }

}
ShortEmpInfoQueryDemo.java
package org.o7planning.tutorial.hibernate.query;

import java.util.List;

import org.hibernate.query.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.beans.ShortEmpInfo;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class ShortEmpInfoQueryDemo {

    public static void main(String[] args) {
        SessionFactory factory = HibernateUtils.getSessionFactory();

        Session session = factory.getCurrentSession();

        try {
            session.getTransaction().begin();
 
            // Using constructor of ShortEmpInfo
            String sql = "Select new " + ShortEmpInfo.class.getName()
                    + "(e.empId, e.empNo, e.empName)" + " from "
                    + Employee.class.getName() + " e ";

            Query<ShortEmpInfo> query = session.createQuery(sql);
 
            
            // Execute query.
            // Get a List of ShortEmpInfo
            List<ShortEmpInfo> employees = query.getResultList();

            for (ShortEmpInfo emp : employees) {
                System.out.println("Emp: " + emp.getEmpNo() + " : "
                        + emp.getEmpName());
            }
 
            // Commit data.
            session.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            // Rollback in case of an error occurred.
            session.getTransaction().rollback();
        }
    }
    
}

7.4- Query wiederherstellt das einzige Ergebnis

UniqueResultDemo.java
package org.o7planning.tutorial.hibernate.query;

import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Department;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class UniqueResultDemo {

    public static Department getDepartment(Session session, String deptNo) {
        String sql = "Select d from " + Department.class.getName() + " d "//
                + " where d.deptNo= :deptNo ";
        Query<Department> query = session.createQuery(sql);
        query.setParameter("deptNo", deptNo);
        return (Department) query.getSingleResult();
    }

    public static Employee getEmployee(Session session, Long empId) {
        String sql = "Select e from " + Employee.class.getName() + " e "//
                + " where e.empId= :empId ";
        Query<Employee> query = session.createQuery(sql);
        query.setParameter("empId", empId);
        return (Employee) query.getSingleResult();
    }

    public static void main(String[] args) {
        SessionFactory factory = HibernateUtils.getSessionFactory();

        Session session = factory.getCurrentSession();

        try {
            session.getTransaction().begin();

            Department dept = getDepartment(session, "D10");
            Set<Employee> emps = dept.getEmployees();

            System.out.println("Dept Name: " + dept.getDeptName());
            for (Employee emp : emps) {
                System.out.println(" Emp name: " + emp.getEmpName());
            }

            Employee emp = getEmployee(session, 7839L);
            System.out.println("Emp Name: " + emp.getEmpName());

            session.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.getTransaction().rollback();
        }
    }
    
}

8- Was sind Transient, Persistent und Detached ?

DataUtils.java
package org.o7planning.tutorial.hibernate;

import org.hibernate.Session;
import org.hibernate.query.Query;
import org.o7planning.tutorial.hibernate.entities.Department;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class DataUtils {

   public static Department findDepartment(Session session, String deptNo) {
       String sql = "Select d from " + Department.class.getName() + " d "//
               + " Where d.deptNo = :deptNo";
       Query<Department> query = session.createQuery(sql);
       query.setParameter("deptNo", deptNo);
       return query.getSingleResult();
   }

   public static Long getMaxEmpId(Session session) {
       String sql = "Select max(e.empId) from " + Employee.class.getName() + " e ";
       Query<Number> query = session.createQuery(sql);
       Number value = query.getSingleResult();
       if (value == null) {
           return 0L;
       }
       return value.longValue();
   }

   public static Employee findEmployee(Session session, String empNo) {
       String sql = "Select e from " + Employee.class.getName() + " e "//
               + " Where e.empNo = :empNo";
       Query<Employee> query = session.createQuery(sql);
       query.setParameter("empNo", empNo);
       return query.getSingleResult();
   }

}
Das ist das einfache Beispiel für die Verwendung von  Session.persist(Object) um ein Objekt  Transient in DB einzusetzen. Der Begriff vom Objekt  Transitent, Persistent, Detached wird in diesem Beispiel erklärt.
PersistDemo.java
package org.o7planning.tutorial.hibernate.demo;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Department;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class PersistDemo {

   public static void main(String[] args) {
       
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Department department = null;
       Employee emp = null;
       try {
           session.getTransaction().begin();

           Long maxEmpId = DataUtils.getMaxEmpId(session);
           Long empId = maxEmpId + 1;
           
           // Get Persistent object.
           department = DataUtils.findDepartment(session, "D10");
           
           // Create transient object
           emp = new Employee();
           emp.setEmpId(empId);
           emp.setEmpNo("E" + empId);
           emp.setEmpName("Name " + empId);
           emp.setJob("Coder");
           emp.setSalary(1000f);
           emp.setManager(null);
           emp.setHideDate(new Date());
           emp.setDepartment(department);
           
           // Using persist(..)
           // Now 'emp' is managed by Hibernate.
           // it has Persistent status.
           // No action at this time with DB.
           session.persist(emp);

           
           // At this step the data is pushed to the DB.
           // Execute Insert statement.
           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }

       // After the session is closed (commit, rollback, close)
       // Objects 'emp', 'dept' became the Detached objects.
       // It is no longer in the control of the session.        
       System.out.println("Emp No: " + emp.getEmpNo());
       
   }
   
}
Das Ergebnis vom Beispiel-Laufen

9- Das Lebenskreis vom  Hibernate (Hibernate Lifecycle)

Die Klasse  Session vom Hibernate hat die einigen wichtigen Methode. Sie werden in die Gruppen wie die folgenden Illustration geteilt.
Ein Objekt in  Hibernate hat einen der vier Status:
  • Transient    (Vorläufig)
  • Persistent   (Beständig)
  • Removed     (Entfernt)
  • Detached    (Getrennt - im Vergeleich mit der momentan Session)
Wir erklären durch die folgenden Illustration diese Status

Transient:

Falls Sie ein Objekt  java aus ein Entity neu erstellen, hat dieses Objekt den Status von   Transient. Hibernate kennt seinen Existenz nicht. Es wird durch Hibernate nicht kontrolliert.

Persistent

Falls Sie ein Objekt  Entity durch die Methode von  get, load, find, getSingleResult,.. wiederherstellen, haben Sie ein Objekt, das einem Rekord unter die Database entspricht. Das Objekt hat den Status vom   Persistent. Es wird durch  Hibernate ​​​​​​​kontrolliert.

Transient -> Persistent

Session ruft ein der Methode von  save, saveOrUpdate, persist, merge , das das Objekt  Transient zum Management von  Hibernate schieben wird und das Objekt wechselt zum Status von   Persistent. Es entspricht der Aktion von insert oder  update in  Database.

Persistent -> Detached

Das Objekt  Session ruft das Method  evict(..) oder  clear() um die Objekte mit dem Status von  Persistent aus dem Management von  Hibernate auszuschließen. Jetzt haben diese Objekte den neuen Status von Detached (getrennt).  Wenn es nicht wieder eingefügt wird( Re-Attached), wird es nach dem normalen Mechanimus durch Java Garbage Collector entfernt.

Detached -> Persistent

Die Verwendung von einer der Methode : update(..), saveOrUpdate(..), merge(..) wird ein Objekt mit dem Status vom  Detached in dem Management von  Hibernate setzen. Es ist äquivalent mit der Aktion  update oder  insert unter  Database. Das Objekt wird zum Status von  Persistent wechseln.

Persistent -> Removed

Das Objekt  Session ruft das Method   remove(..) oder delete(..) um ein Objekt (Rekord) zu löschen. Das Objekt  Persistent wird zum Status  Removed (entfernt) wechseln.

10- Die Manipulation von Insert, Update, Delete mit Hibernate

10.1- Persistent

PersistentDemo.java
package org.o7planning.tutorial.hibernate.demo;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Department;

public class PersistentDemo {

   public static void main(String[] args) {
       
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Department department = null;

       try {
           session.getTransaction().begin();

           System.out.println("- Finding Department deptNo = D10...");
      
           // Persistent object.
           department = DataUtils.findDepartment(session, "D10");

           System.out.println("- First change Location");
     
           
           // Changing something on Persistent object.
           department.setLocation("Chicago " + System.currentTimeMillis());
           
           System.out.println("- Location = " + department.getLocation());

           System.out.println("- Calling flush...");
   
           // Use session.flush () to actively push the changes to the DB.
           // It works for all changed Persistent objects.
           session.flush();

           System.out.println("- Flush OK");

           System.out.println("- Second change Location");
           
           // Change something on Persistent object
           department.setLocation("Chicago " + System.currentTimeMillis());
 
           // Print out location
           System.out.println("- Location = " + department.getLocation());

           System.out.println("- Calling commit...");
 
           // Commit
           session.getTransaction().commit();

           System.out.println("- Commit OK");
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
 
       // Create the session after it had been closed earlier
       // (Cause by commit or update)
       session = factory.getCurrentSession();
       try {
           session.getTransaction().begin();

           System.out.println("- Finding Department deptNo = D10...");
           
           // Query lại Department D10.
           
           department = DataUtils.findDepartment(session, "D10");
 
           // Print out location
           System.out.println("- D10 Location = " + department.getLocation());

           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
   }
   
}
Das Ergebnis der Durchführung des Beispiel

10.2- Transient --> Persistent : Die Überblick

10.3- Transient --> Persistent : Die Verwendung von persist(Object)

PersistTransientDemo.java
package org.o7planning.tutorial.hibernate.demo;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;
import org.o7planning.tutorial.hibernate.entities.Timekeeper;

public class PersistTransientDemo {

   private static DateFormat df = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");

   private static Timekeeper persist_Transient(Session session, Employee emp) {
 
       // Note:
       // Configuring of timekeeperId
       // @GeneratedValue(generator = "uuid")
       // @GenericGenerator(name = "uuid", strategy = "uuid2")            
       Timekeeper tk1 = new Timekeeper();

       tk1.setEmployee(emp);
       tk1.setInOut(Timekeeper.IN);
       tk1.setDateTime(new Date());
  
       // Now, 'tk1' is transient object
       System.out.println("- tk1 Persistent? " + session.contains(tk1));

       System.out.println("====== CALL persist(tk).... ===========");
 
       
       // Hibernate assign value to Id of 'tk1'
       // No action to DB.
       session.persist(tk1);
 
       System.out
               .println("- tk1.getTimekeeperId() = " + tk1.getTimekeeperId());
 
       
       // Now 'tk1' is Persistent object.
       // But no action with DB.
       // ==> true
       System.out.println("- tk1 Persistent? " + session.contains(tk1));

       System.out.println("- Call flush..");
 
       
       // Flush data to DB.
       // Hibernate execute insert statement.
       session.flush();

       String timekeeperId = tk1.getTimekeeperId();
       System.out.println("- timekeeperId = " + timekeeperId);
       System.out.println("- inOut = " + tk1.getInOut());
       System.out.println("- dateTime = " + df.format(tk1.getDateTime()));
       System.out.println();
       return tk1;
   }

   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Employee emp = null;
       try {
           session.getTransaction().begin();

           emp = DataUtils.findEmployee(session, "E7499");

           persist_Transient(session, emp);

           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
   }
   
}
Das Ergebnis der Durchführung des Beispiel

10.4- Transient --> Persistent :  save(Object) verwenden

SaveTransientDemo.java
package org.o7planning.tutorial.hibernate.demo;

import java.io.Serializable;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;
import org.o7planning.tutorial.hibernate.entities.Timekeeper;

public class SaveTransientDemo {

   private static DateFormat df = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");

   private static Timekeeper persist_Transient(Session session, Employee emp) {
     
       // See configuration of timekeeperId:
       // @GeneratedValue(generator = "uuid")
       // @GenericGenerator(name = "uuid", strategy = "uuid2")
       // Create an Object, Transitent state.        
       Timekeeper tk2 = new Timekeeper();

       tk2.setEmployee(emp);
       tk2.setInOut(Timekeeper.IN);
       tk2.setDateTime(new Date());

       // Now 'tk3' are state Transient.        
       System.out.println("- tk2 Persistent? " + session.contains(tk2));

       System.out.println("====== CALL save(tk).... ===========");

       // save() very similar to persist()
       // save() return ID, persist() return void.
       // Hibernate assign ID value to 'tk2', no action with DB
       // And return ID of 'tk2'.        
       Serializable id = session.save(tk2);

       System.out.println("- id = " + id);

       //
       System.out
               .println("- tk2.getTimekeeperId() = " + tk2.getTimekeeperId());

     
       // Now, 'tk2' has Persistent state
       // It has been managed in Session.
       // ==> true
       System.out.println("- tk2 Persistent? " + session.contains(tk2));

       System.out.println("- Call flush..");

       // To push data into the DB, call flush().
       // If not call flush() data will be pushed to the DB when calling commit().
       // Will execute insert statement.
       session.flush();

       String timekeeperId = tk2.getTimekeeperId();
       System.out.println("- timekeeperId = " + timekeeperId);
       System.out.println("- inOut = " + tk2.getInOut());
       System.out.println("- dateTime = " + df.format(tk2.getDateTime()));
       System.out.println();
       return tk2;
   }

   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Employee emp = null;
       try {
           session.getTransaction().begin();

           emp = DataUtils.findEmployee(session, "E7499");

           persist_Transient(session, emp);

           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
   }
}
Das Ergebnis der Durchführung des Beispiel

10.5- Transient --> Persistent :  saveOrUpdate(Object) verwenden

SaveOrUpdateTransientDemo.java
package org.o7planning.tutorial.hibernate.demo;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;
import org.o7planning.tutorial.hibernate.entities.Timekeeper;

public class SaveOrUpdateTransientDemo {

   private static DateFormat df = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");

   private static Timekeeper saveOrUpdate_Transient(Session session,
           Employee emp) {

       // See configuration of timekeeperId:
       // @GeneratedValue(generator = "uuid")
       // @GenericGenerator(name = "uuid", strategy = "uuid2")
       // Create an Object, Transitent state.
       Timekeeper tk3 = new Timekeeper();

       tk3.setEmployee(emp);
       tk3.setInOut(Timekeeper.IN);
       tk3.setDateTime(new Date());

       // Now 'tk3' are state Transient.
       System.out.println("- tk3 Persistent? " + session.contains(tk3));

       System.out.println("====== CALL saveOrUpdate(tk).... ===========");

       // Here Hibernate checks, 'tk3' have ID or not (timekeeperId)
       // If no, it will be assigned automatically
       session.saveOrUpdate(tk3);

       System.out
               .println("- tk3.getTimekeeperId() = " + tk3.getTimekeeperId());

       // Now 'tk3' has Persistent state
       // It has been managed in Session.
       // But no action insert, or update to DB.
       // ==> true
       System.out.println("- tk3 Persistent? " + session.contains(tk3));

       System.out.println("- Call flush..");

       // To push data into the DB, call flush().
       // If not call flush() data will be pushed to the DB when calling commit().
       // Now possible to Insert or Update DB. (!!!)
       // Depending on the ID of 'tk3' exists in the DB or not
       session.flush();

       String timekeeperId = tk3.getTimekeeperId();
       System.out.println("- timekeeperId = " + timekeeperId);
       System.out.println("- inOut = " + tk3.getInOut());
       System.out.println("- dateTime = " + df.format(tk3.getDateTime()));
       System.out.println();
       return tk3;
   }

   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Employee emp = null;
       try {
           session.getTransaction().begin();

           emp = DataUtils.findEmployee(session, "E7499");

           saveOrUpdate_Transient(session, emp);

           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
   }
}
Das Ergebnis der Durchführung des Beispiel

10.6- Transient --> Persistent :merge(Object) verwenden

MergeTransientDemo.java
package org.o7planning.tutorial.hibernate.demo;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;
import org.o7planning.tutorial.hibernate.entities.Timekeeper;

public class MergeTransientDemo {

   private static DateFormat df = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");

   private static Timekeeper saveOrUpdate_Transient(Session session,
           Employee emp) {
     
       // Note:
       // Configuring of timekeeperId
       // @GeneratedValue(generator = "uuid")
       // @GenericGenerator(name = "uuid", strategy = "uuid2")        
       Timekeeper tk4 = new Timekeeper();

       tk4.setEmployee(emp);
       tk4.setInOut(Timekeeper.IN);
       tk4.setDateTime(new Date());

       // Now 'tk4' Transient status.
       System.out.println("- tk4 Persistent? " + session.contains(tk4));

       System.out.println("====== CALL merge(tk).... ===========");

 
       // Hibernate2 has method saveOrUpdateCopy
       // Hibernate3 change saveOrUpdateCopy to merge
       // So there will be similarities between the two methods merge and copyOrUpdate
       // Here Hibernate check tk4 has ID or not
       // If not, Hibernate assign value to ID of tk4
       // Return copy of tk4.
       Timekeeper tk4Copy = (Timekeeper) session.merge(tk4);

       System.out
               .println("- tk4.getTimekeeperId() = " + tk4.getTimekeeperId());

   
       // Now 'tk4' still Transient state.
       // and 'tk4Copy' has Persistent status
       // No action with DB (insert or update).
       System.out.println("- tk4 Persistent? " + session.contains(tk4));

       // 'tk4Copy' has Persistent status
       // ==> true
       System.out
               .println("- tk4Copy Persistent? " + session.contains(tk4Copy));

       System.out.println("- Call flush..");
       
     
       // This time have Insert or Update to DB. (!!!)
       session.flush();

       // 'tk4' still Transitent, after flush().
       // merge(..) safer than saveOrUpdate().
       System.out.println("- tk4 Persistent? " + session.contains(tk4));

       //
       String timekeeperId = tk4.getTimekeeperId();
       System.out.println("- timekeeperId = " + timekeeperId);
       System.out.println("- inOut = " + tk4.getInOut());
       System.out.println("- dateTime = " + df.format(tk4.getDateTime()));
       System.out.println();
       return tk4;
   }

   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Employee emp = null;
       try {
           session.getTransaction().begin();

           emp = DataUtils.findEmployee(session, "E7499");

           saveOrUpdate_Transient(session, emp);

           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
   }
}
Das Ergenis der Durchführung des Beispiel

10.7- Persistent --> Detached

Ein Objekt mit dem Status von  Persistent (durch  Hibernate managet) kann zum Status vom  Detached (getrennt, durch  Hibernate nicht managet)  durch das folgende Method von  Session:

  • evict(Object)
Ein Objekt aus dem Management vom  Hibernate auschließen
  • clear()
Alle Objekte aus dem Management vom  Hibernate ausschliessen
Achtung: Wenn das Objekt  Session  ein der Methode: commit(), close(), rollback() aufruft, wird die Session enden. Alle Objekte  Persistence von dieser  session werden als  Detached für eine neue Session
EvictDemo.java
package org.o7planning.tutorial.hibernate.demo;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class EvictDemo {

   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Employee emp = null;
       try {
           session.getTransaction().begin();

           // This is object has Persistent status
           emp = DataUtils.findEmployee(session, "E7499");

           // ==> true
           System.out.println("- emp Persistent? " + session.contains(emp));

     
           // using evict() to evicts a single object from the session
           session.evict(emp);

           // Now 'emp' has Detached status
           // ==> false
           System.out.println("- emp Persistent? " + session.contains(emp));

       
           // All change on the 'emp' will not update
           // if not reatach 'emp' to session
           emp.setEmpNo("NEW");

           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
   }
}
Das Ergebnis der Durchführung eines Beispiel
ClearDemo.java
package org.o7planning.tutorial.hibernate.demo;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Department;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class ClearDemo {
   
   
   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session = factory.getCurrentSession();
       Employee emp = null;
       Department dept = null;
       try {
           session.getTransaction().begin();

           // It is an object has Persistent status.
           emp = DataUtils.findEmployee(session, "E7499");
           dept = DataUtils.findDepartment(session, "D10");

       
           // clear() evicts all the objects in the session.
           session.clear();


           // Now 'emp' & 'dept' has Detached status
           // ==> false
           System.out.println("- emp Persistent? " + session.contains(emp));
           System.out.println("- dept Persistent? " + session.contains(dept));

           // All change on the 'emp' will not update
           // if not reatach 'emp' to session
           emp.setEmpNo("NEW");

           dept = DataUtils.findDepartment(session, "D20");
           System.out.println("Dept Name = "+ dept.getDeptName());

           session.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session.getTransaction().rollback();
       }
   }
}
Das Ergebnis der Durchführung eines Beispiel

10.8- Detached --> Persistent : Die Überblick

Ein Objekt mit dem Status vom  Detached (aus dem Management von  Hibernate getrennt) kann durch einige Methode von Session wieder eingefügt (Re-attach) werden. 
  • update(Object)
  • saveOrUpdate(Object)
  • merge(Object)
  • refresh(Object)
  • lock(Object)
Sie können in die folgenden Beispiele den Unterschied zwischen die Methode sehen.

10.9- Detached --> Persistent : update(Object) verwenden

UpdateDetachedDemo.java
package org.o7planning.tutorial.hibernate.demo;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class UpdateDetachedDemo {

   public static void main(String[] args) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session1 = factory.getCurrentSession();
       Employee emp = null;
       try {
           session1.getTransaction().begin();

           // This is a Persistent object.
           emp = DataUtils.findEmployee(session1, "E7499");

           // session1 was closed after a commit is called.
           session1.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session1.getTransaction().rollback();
       }

       // Open other session
       Session session2 = factory.getCurrentSession();

       try {
           session2.getTransaction().begin();

       
           // Check state of 'emp'
           // ==> false
           System.out.println("- emp Persistent? " + session2.contains(emp));

           System.out.println("Emp salary: " + emp.getSalary());

           emp.setSalary(emp.getSalary() + 100);

         
           // update (..) is only used for Detached object.
           // (Not for Transient object).
           // Use the update (emp) to bring back emp Persistent state.            
           session2.update(emp);
         
           // Call flush
           // Update statement will be called.
           session2.flush();

           System.out.println("Emp salary after update: " + emp.getSalary());

           // session2 was closed after a commit is called.
           session2.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session2.getTransaction().rollback();
       }

   }
}
Das Ergebnis der Durchführung des Beispiel

10.10- Detached --> Persistent : saveOrUpdate(Object) verwenden

SaveOrUpdateDetachedDemo.java
package org.o7planning.tutorial.hibernate.demo;

import java.util.Random;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class SaveOrUpdateDetachedDemo {

   public static void main(String[] args) {

       // An object Detached state.
       Employee emp = getEmployee_Detached();

       System.out.println(" - GET EMP " + emp.getEmpId());

       // Random delete or not delete Employee
       boolean delete = deleteOrNotDelete(emp.getEmpId());

       System.out.println(" - DELETE? " + delete);

       // Call saveOrUpdate for detached object.
       saveOrUpdate_test(emp);
     
       // After call saveOrUpdate()
       System.out.println(" - EMP ID " + emp.getEmpId());
   }

   
   // Return Employee object has Detached state
   private static Employee getEmployee_Detached() {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session1 = factory.getCurrentSession();
       Employee emp = null;
       try {
           session1.getTransaction().begin();

           Long maxEmpId = DataUtils.getMaxEmpId(session1);
           System.out.println(" - Max Emp ID " + maxEmpId);

           Employee emp2 = DataUtils.findEmployee(session1, "E7839");

           Long empId = maxEmpId + 1;
           emp = new Employee();
           emp.setEmpId(empId);
           emp.setEmpNo("E" + empId);

           emp.setDepartment(emp2.getDepartment());
           emp.setEmpName(emp2.getEmpName());

           emp.setHideDate(emp2.getHideDate());
           emp.setJob("Test");
           emp.setSalary(1000F);

           // emp has been managed by Hibernate
           session1.persist(emp);

           // session1 was closed after a commit is called.
           // An Employee record are insert into DB.            
           session1.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session1.getTransaction().rollback();
       }
       // Session1 closed 'emp' switch to Detached state.
       return emp;
   }

   // Random: delete or not delete.
   private static boolean deleteOrNotDelete(Long empId) {
       // A random number 0-9
       int random = new Random().nextInt(10);
       if (random < 5) {
           return false;
       }
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session2 = factory.getCurrentSession();
       try {
           session2.getTransaction().begin();
           String sql = "Delete " + Employee.class.getName() + " e "
                   + " where e.empId =:empId ";
           Query query = session2.createQuery(sql);
           query.setParameter("empId", empId);

           query.executeUpdate();

           session2.getTransaction().commit();
           return true;
       } catch (Exception e) {
           e.printStackTrace();
           session2.getTransaction().rollback();
           return false;
       }
   }

   private static void saveOrUpdate_test(Employee emp) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       // Open other session
       Session session3 = factory.getCurrentSession();

       try {
           session3.getTransaction().begin();

           // Check state of emp
           // ==> false
           System.out.println(" - emp Persistent? " + session3.contains(emp));

           System.out.println(" - Emp salary before update: "
                   + emp.getSalary());
         
           // Set new salary for Detached emp object.
           emp.setSalary(emp.getSalary() + 100);

         
           // Using saveOrUpdate(emp) to switch emp to Persistent state
           // Note: If exists object same ID in session, this method raise Exception
           //
           // Now, no action with DB.            
           session3.saveOrUpdate(emp);
         
           // By pushing data into the DB.
           // It will call a Insert or update statement.
           // If the record is deleted before ==> insert
           // Else ==> update.    
           session3.flush();

           System.out
                   .println(" - Emp salary after update: " + emp.getSalary());

           // session3 was closed after a commit is called.
           session3.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session3.getTransaction().rollback();
       }

   }

}
Das Beispiel oben mehrmals durchführen, dann können Sie sehen, dass die zwei Situationen  saveOrUpdate  die Aktionen : Insert oder Update in DB erstellen
INSERT:
UPDATE:

10.11- Detached --> Persistent : merge(Object) verwenden

Hibernate Version 2 hat das Method  saveOrUpdateCopy(Object), ab die Version 3 umbenennet sie  merge(Object). Deshalb hat  merge die Gemeinsamkeit und den kleinen Unterschied im Vergleich von  saveOrUpdate.
  • merge(Object) setzt das Objekt in das Management von Hibernate nicht aber es erstellt eine Kopie dieses Objekt und managet das Kopie-Objekt 
  • Wenn Sie saveOrUpdate(aObject) auffrufen während bObject durch Hibernate managet wird und das gleiche ID mit aObject hat, wird eine Ausnahme geworfen. Bei der Verwendung von merge(aObject) wird diese Ausnahme nicht getroffen.
MergeDetachedDemo.java
package org.o7planning.tutorial.hibernate.demo;

import java.util.Random;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class MergeDetachedDemo {

   public static void main(String[] args) {

       // An object has Detached status
       Employee emp = getEmployee_Detached();

       System.out.println(" - GET EMP " + emp.getEmpId());

       // Random: delete or not delete the Employee by ID.
       boolean delete = deleteOrNotDelete(emp.getEmpId());

       System.out.println(" - DELETE? " + delete);

       // Call saveOrUpdate Detached object
       saveOrUpdate_test(emp);

       // After call saveOrUpdate
       // ...
       System.out.println(" - EMP ID " + emp.getEmpId());
   }

 
   // Method return Employee object
   // and has Detached status.
   private static Employee getEmployee_Detached() {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session1 = factory.getCurrentSession();
       Employee emp = null;
       try {
           session1.getTransaction().begin();

           Long maxEmpId = DataUtils.getMaxEmpId(session1);
           System.out.println(" - Max Emp ID " + maxEmpId);

           Employee emp2 = DataUtils.findEmployee(session1, "E7839");

           Long empId = maxEmpId + 1;
           emp = new Employee();
           emp.setEmpId(empId);
           emp.setEmpNo("E" + empId);

           emp.setDepartment(emp2.getDepartment());
           emp.setEmpName(emp2.getEmpName());

           emp.setHideDate(emp2.getHideDate());
           emp.setJob("Test");
           emp.setSalary(1000F);

           // 'emp' has Persistant state
           session1.persist(emp);

       
           // session1 was closed after a commit is called.
           // An Employee record are insert into DB.
           session1.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session1.getTransaction().rollback();
       }
       // session1 closed, 'emp' switched Detached state.
       return emp;
   }

 
   // Delete Employee by ID
   // Random: delete or not delete
   private static boolean deleteOrNotDelete(Long empId) {
       // A random number 0-9
       int random = new Random().nextInt(10);
       if (random < 5) {
           return false;
       }
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session2 = factory.getCurrentSession();
       try {
           session2.getTransaction().begin();
           String sql = "Delete " + Employee.class.getName() + " e "
                   + " where e.empId =:empId ";
           Query query = session2.createQuery(sql);
           query.setParameter("empId", empId);

           query.executeUpdate();

           session2.getTransaction().commit();
           return true;
       } catch (Exception e) {
           e.printStackTrace();
           session2.getTransaction().rollback();
           return false;
       }
   }

   private static void saveOrUpdate_test(Employee emp) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       // Open other session
       Session session3 = factory.getCurrentSession();

       try {
           session3.getTransaction().begin();

       
           // The fact, 'emp' has Detached state
           // It is not managed by Hibernate.
           // Check the status of emp:
           // ==> false
           System.out.println(" - emp Persistent? " + session3.contains(emp));

           System.out.println(" - Emp salary before update: "
                   + emp.getSalary());

           // Set new salary for Detached object 'emp'
           emp.setSalary(emp.getSalary() + 100);

       
           // merge(emp) return empMerge, a copy of 'emp',
           // empMerge managed by Hibernate
           // 'emp' still in Detached state
           //
           // At this time there is no action regarding DB.
           Employee empMerge = (Employee) session3.merge(emp);

           // ==> false
           System.out.println(" - emp Persistent? " + session3.contains(emp));
           // ==> true
           System.out.println(" - empMerge Persistent? "
                   + session3.contains(empMerge));

         
           // Push data into the DB.
           // Here it is possible to create the Insert or Update on DB.
           // If the corresponding record has been deleted by someone, it insert
           // else it update
           session3.flush();

           System.out
                   .println(" - Emp salary after update: " + emp.getSalary());

           // session3 closed after a commit is called.
           session3.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session3.getTransaction().rollback();
       }

   }

}
Das Ergebnis der Durchführung des Beispiel
INSERT:
UPDATE:

10.12- Detached --> Persistent : refresh(Object) verwenden

RefreshDetachedDemo.java
package org.o7planning.tutorial.hibernate.demo;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.o7planning.tutorial.hibernate.DataUtils;
import org.o7planning.tutorial.hibernate.HibernateUtils;
import org.o7planning.tutorial.hibernate.entities.Employee;

public class RefreshDetachedDemo {

   public static void main(String[] args) {

       // an Object with Detached status
       Employee emp = getEmployee_Detached();

       System.out.println(" - GET EMP " + emp.getEmpId());

       // Refresh Object  
       refresh_test(emp);
   }

 
   // Return Employee object has Detached state
   private static Employee getEmployee_Detached() {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       Session session1 = factory.getCurrentSession();
       Employee emp = null;
       try {
           session1.getTransaction().begin();

           emp = DataUtils.findEmployee(session1, "E7839");

           // session1 was closed after a commit is called.
           // An Employee record are insert into DB.
           session1.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session1.getTransaction().rollback();
       }
       // Session1 closed 'emp' switch to Detached state.
       return emp;
   }

   private static void refresh_test(Employee emp) {
       SessionFactory factory = HibernateUtils.getSessionFactory();

       // Open other session
       Session session2 = factory.getCurrentSession();

       try {
           session2.getTransaction().begin();

       
           // Check the status of 'emp' (Detached)
           // ==> false
           System.out.println(" - emp Persistent? " + session2.contains(emp));

           System.out.println(" - Emp salary before update: "
                   + emp.getSalary());

            // Set new salary for 'emp'.
           emp.setSalary(emp.getSalary() + 100);

         
           // refresh: make a query statement
           // and switch 'emp' to Persistent state
           // The changes are ignored
           session2.refresh(emp);

           // ==> true
           System.out.println(" - emp Persistent? " + session2.contains(emp));

           System.out.println(" - Emp salary after refresh: "
                   + emp.getSalary());
           
           session2.getTransaction().commit();
       } catch (Exception e) {
           e.printStackTrace();
           session2.getTransaction().rollback();
       }

   }

}
Das Ergebnis der Durchführung des Beispiel

10.13- Detached --> Persistent : Using lock(Object)

  • TODO...

11- Aus Entity Klassen die Tabelle erstellen

Hibernate erlaubt Sie, aus Entity Klassen die Tabelle mit den vollen Einschränkungen zwischen die Tabelle  zu erstellen