Deploying Spring Boot Application on Tomcat Server

1- Objective of post

In this post, I will guide you for implementing a Spring Boot application on Tomcat Server. One of the characteristics of the Tomcat is compact. The capacity of the Tomcat is only about 10MB, and an open source Java Web Server.
Ensure that you have installed the Tomcat successfully. If not, you can refer to Tomcat installations as in the following post:
In fact, the Spring Boot application can be packaged into an Executable JAR file. With this file you can run the application directly without needing to deploy it on any Web Server. The Executable JAR file may not be compatible with all Web servers, therefore, you want to deploy it on a particular Web server, you need to package the Spring Boot application into a WAR file.

2- Edit code

I have a  Spring Boot project here, developed by  Eclipse IDE. When creating the  Spring Boot project, you have 2 choices to pack this project such as  WAR or  JAR.
When you create the  Spring Boot project with the  "Packaging = War" option, Eclipse will create 2 classes such as  "AbcApplication & ServletInitializer" for you. The  WAR files are suitable for being deployed on   Web Servers.
While, if you create a  Spring Boot project with the  "Packaging = Jar" choice, only one  AbcApplication class will be created. When the  Spring Boot application is packed into the  JAR file, it can be independently executabe without being deployed on any  Web Server. But the   JAR file is not suitable to be deployed on  Web Servers.

WAR File.

If you have an available  Spring Boot, you need to correct packaging method into  WAR:
On the  Eclipse, open the  pom.xml file, and change packaging method into  war.
If your project doesn't have a  ServletInitializer class, create it.
ServletInitializer.java
package org.o7planning.example;

import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

public class ServletInitializer extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(SpringBootTomcatApplication.class);
    }

}
Add the following configuration snippet to the  pom.xml:
** pom.xml **
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
</dependency>
If there are more than one  Application class in your project, please tell the  Spring Boot which class will be used for your application.
** pom.xml **
<properties>
        <start-class>org.o7planning.example.OtherSpringBootWebApplication</start-class>
</properties>

3- Install Spring Boot

In the next step, you need to use  Maven to create   WAR file. You have to ensure that your  Eclipse is using   JDK instead of  JRE. If not, en error will occur in this process.
Right click on the Project and select:
  • Run As/Maven Install

At this moment, you will have a  WAR file in the target folder of the project, you can use this file to deploy on the  Tomcat Server.
See also: