SpringBootServletInitializer
last modified July 23, 2023
In this article we show how to deploy a Spring Boot application from a traditional WAR deployment.
The current trend is to deploy Spring Boot application from an executable JAR. (See the Spring Boot first web application for details how to start a simple web application from JAR.)
Spring is a popular Java application framework. Spring Boot is an effort to create stand-alone, production-grade Spring based applications with minimal effort.
SpringBootServletInitializer
SpringBootServletInitializer is an interface to run
SpringApplication from a traditional WAR deployment. It binds Servlet, Filter
and ServletContextInitializer beans from the application context to the server.
SpringBootServletInitializer example
The application creates a simple Spring Boot RESTful application and packages it into a WAR.
build.gradle
...
src
├───main
│ ├───java
│ │ └───com
│ │ └───zetcode
│ │ │ Application.java
│ │ └───controller
│ │ MyController.java
│ └───resources
└───test
└───java
This is the project structure.
plugins {
id 'org.springframework.boot' version '3.1.1'
id 'io.spring.dependency-management' version '1.1.0'
id 'java'
}
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '17'
repositories {
mavenCentral()
}
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-web'
}
This is the Gradle build file. The spring-boot-starter-web is
starter for building web, including RESTful, applications using Spring MVC.
The application is packaged into a WAR file.
package com.zetcode.controller;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class MyController {
@GetMapping(value = "/", produces = MediaType.TEXT_PLAIN_VALUE)
public String index() {
return "Hello there";
}
}
This is the controller class for the Spring Boot web application. A controller
is decorated with the @Restontroller annotation.
@GetMapping(value = "/", produces = MediaType.TEXT_PLAIN_VALUE)
public String index() {
return "Hello there";
}
A GET request to the home page returns a string. The binding is done with
@GetMapping.
package com.zetcode;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
@SpringBootApplication
public class Application extends SpringBootServletInitializer {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
The Application sets up the Spring Boot application. It extends
from SpringBootServletInitializer so that it can be deployed as
a WAR.
The application can be run both by deploying the WAR on a Tomcat server and executing it as a self-executable web archive with embedded Tomcat.
In this article we have created our first Spring Boot web application deployable from a traditional WAR.