Java Commons Logging Tutorial with Examples

What is Commons Logging?
The goal of documentation
Commons Logging + Log4J Logger

1. What is Commons Logging?

In your Java application, you want to write code to log messages during its working? You can use one of three library Logger follows:

Log4J Logger
Jdk14 Logger
Simple Logger

Commons Logging is a library that allows you to work with one of three libraries above easier. So to write a program log, Stand alone 'Commons Logging' can not be a Logger. A similar way, you work with java.io to process stream, Commons IO is a library written based on java.io help you more easily handled IO, Common IO irreplaceable java.io.

So you have 3 choices:

What you choose does not matter, Logger are treated the same way with the support of the Commons Logging.

2. The goal of documentation

In this guide I will show you how to work with:

Commons Logging + Log4J Logger

3. Commons Logging + Log4J Logger

Library

Commons Logging Library:

http://mvnrepository.com/artifact/commons-logging/commons-logging

Maven:

<dependency>
    <groupId>commons-logging</groupId>
    <artifactId>commons-logging</artifactId>
    <version>1.1.3</version>
</dependency>

Log4J Logger Library:

Maven:

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

Create project

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>CommonsLoggingTutorial</artifactId>
   <version>0.0.1-SNAPSHOT</version>

   <dependencies>
       <dependency>
           <groupId>commons-logging</groupId>
           <artifactId>commons-logging</artifactId>
           <version>1.1.3</version>
       </dependency>
       <dependency>
           <groupId>log4j</groupId>
           <artifactId>log4j</artifactId>
           <version>1.2.17</version>
       </dependency>
   </dependencies>
   
</project>

A simple example HelloWorld (Log to Console)

In this step we will make a simple HelloWorld example, it will write Log to the console.

HelloWorld.java

package org.o7planning.tutorial.commonslogging;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class HelloWorld {

   private static final Log log = LogFactory.getLog(HelloWorld.class);

   public static void main(String[] args) {
       log.debug("Example debug message ..");
       log.info("Example info message ..");
       log.warn("Example warn message ..");
       log.error("Example error message ..");
       log.fatal("Example fatal message ..");  
   }
}

commons-logging.properties

org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger

log4j.configuration=log4j.properties

log4j.properties

log4j.rootLogger=DEBUG, CA, NTEventLog

#Console Appender
log4j.appender.CA=org.apache.log4j.ConsoleAppender
log4j.appender.CA.layout=org.apache.log4j.PatternLayout
log4j.appender.CA.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n

In fact you can configure Commons Logging to use other Logger libraries, not log4j:

Run class HelloWorld:

With Log4j you can configure in the xml file, and the xml configuration is easy and straightforward than properties file.

Open file commons-logging.properties and change:

commons-logging.properties

org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger

log4j.configuration=log4j.xml

log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

   <appender name="MyConsole" class="org.apache.log4j.ConsoleAppender">
       <param name="Target" value="System.out" />
       <layout class="org.apache.log4j.PatternLayout">
           <param name="ConversionPattern" value="%-4r [%t] %-5p %c %x - %m%n" />
       </layout>
   </appender>



   <root>
       <priority value="debug" />
       <appender-ref ref="MyConsole" />
   </root>

</log4j:configuration>

Running class HelloWorld and view Log in Console.

For example, more complex (Log out file)

Next we will continue with a more complex example, the Log to file.

AdminApplication.java

package org.o7planning.tutorial.commonslogging.admin;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class AdminApplication {

   private static final Log log = LogFactory.getLog(AdminApplication.class);

   public static void main(String[] args) {
       log.debug("Example debug message ..");
       log.info("Example info message ..");
       log.warn("Example warn message ..");
       log.error("Example error message ..");
       log.fatal("Example fatal message ..");

       try {
           raiseException();
       } catch (Exception e) {
           log.fatal("<Some Object>", e);
       }
   }

   private static void raiseException() throws Exception {
       throw new Exception("Test Exception");
   }
}

FrontEndApplication.java

package org.o7planning.tutorial.commonslogging.frontend;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class FrontEndApplication {

   private static final Log log = LogFactory.getLog(FrontEndApplication.class);

   public static void main(String[] args) {
       log.debug("Example debug message ..");
       log.info("Example info message ..");
       log.warn("Example warn message ..");
       log.error("Example error message ..");
       log.fatal("Example fatal message ..");
   }
}

Cấu hình thêm vào trong log4j.xml, thêm vào đoạn cấu hình:

  <appender name="AdminFileAppender" class="org.apache.log4j.FileAppender">
      <param name="File" value="logs/admin.log" />
      <layout class="org.apache.log4j.PatternLayout">
          <param name="ConversionPattern"
              value="%d{dd MMM yyyy HH:mm:ss,SSS} {%t} %-5p %c %x - %m%n" />
      </layout>
  </appender>

  <appender name="FrontEndFileAppender" class="org.apache.log4j.FileAppender">
      <param name="File" value="logs/frontEnd.log" />
      <layout class="org.apache.log4j.PatternLayout">
          <param name="ConversionPattern"
              value="%d{dd MMM yyyy HH:mm:ss,SSS} {%t} %-5p %c %x - %m%n" />
      </layout>
  </appender>

  <!-- logger name must by package name! -->
  <logger name="org.o7planning.tutorial.commonslogging.admin">
      <level value="ERROR" />
      <appender-ref ref="AdminFileAppender" />
  </logger>

  <!-- logger name must by package name! -->
  <logger name="org.o7planning.tutorial.commonslogging.frontend">
      <level value="DEBUG" />
      <appender-ref ref="FrontEndFileAppender" />
  </logger>

log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

  <appender name="MyConsole" class="org.apache.log4j.ConsoleAppender">
      <param name="Target" value="System.out" />
      <layout class="org.apache.log4j.PatternLayout">
          <param name="ConversionPattern" value="%-4r [%t] %-5p %c %x - %m%n" />
      </layout>
  </appender>




  <appender name="AdminFileAppender" class="org.apache.log4j.FileAppender">
      <param name="File" value="logs/admin.log" />
      <layout class="org.apache.log4j.PatternLayout">
          <param name="ConversionPattern"
              value="%d{dd MMM yyyy HH:mm:ss,SSS} {%t} %-5p %c %x - %m%n" />
      </layout>
  </appender>

  <appender name="FrontEndFileAppender" class="org.apache.log4j.FileAppender">
      <param name="File" value="logs/frontEnd.log" />
      <layout class="org.apache.log4j.PatternLayout">
          <param name="ConversionPattern"
              value="%d{dd MMM yyyy HH:mm:ss,SSS} {%t} %-5p %c %x - %m%n" />
      </layout>
  </appender>

  <!-- logger name must by package name! -->
  <logger name="org.o7planning.tutorial.commonslogging.admin">
      <level value="ERROR" />
      <appender-ref ref="AdminFileAppender" />
  </logger>

  <!-- logger name must by package name! -->
  <logger name="org.o7planning.tutorial.commonslogging.frontend">
      <level value="DEBUG" />
      <appender-ref ref="FrontEndFileAppender" />
  </logger>


  <root>
      <priority value="debug" />
      <appender-ref ref="MyConsole" />
  </root>

</log4j:configuration>

There is a note on the order of tags when you configure log4j.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

    <!-- render -->
    <renderer></renderer>
    <renderer></renderer>
    <renderer></renderer>
    
    <!-- appender -->
    <appender></appender>
    <appender></appender>
    <appender></appender>
    
    
    <!-- plugin -->
    <plugin></plugin>
    <plugin></plugin>
    <plugin></plugin>
    
    <!-- logger -->
    <logger></logger>
    <logger></logger>
    <logger></logger>
    
    <!-- category -->
    <category></category>
    <category></category>
    <category></category>
    
    <!-- root -->
    <root></root>
    <root></root>
    <root></root>
    
    <!-- loggerfactory -->
    <loggerfactory></loggerfactory>
    <loggerfactory></loggerfactory>
    <loggerfactory></loggerfactory>
    
    <!-- categoryfactory -->
    <categoryfactory></categoryfactory>
    <categoryfactory></categoryfactory>
    <categoryfactory></categoryfactory>

</log4j:configuration>

Run class AdminApplication:

Run class FrontEndApplication

A folder 'logs' has been created and has two log files (admin.log & frontEnd.log)

Java Commons Logging Tutorial with Examples

1. What is Commons Logging?

2. The goal of documentation

3. Commons Logging + Log4J Logger

Apache Commons **

Java Basic

Apache Commons **

Java Basic

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