Google App Engine + Spring 3 MVC REST example

In this tutorial, we will show you how to develop and deploy a Spring 3.0 MVC REST web application in Google App Engine (GAE) environment.

Tools and technologies used :

Google App Engine Java SDK 1.6.3.1
Spring 3.1.1
JDK 1.6
Eclipse 3.7 + Google Plugin for Eclipse

Note
This example is going to reuse this Spring 3 MVC REST example, modify it and integrate with Google App Engine, you may also interest to read this – GAE + Java + Eclipse example

1. New Web Application Project

In Eclipse, create a new Web Application project, named as “SpringMVCGoogleAppEngine“.

The “Google Plugin for Eclipse” will generate a sample of GAE project structure.

2. Spring 3.0 Dependencies

To use Spring MVC + REST in GAE, you need following jars

aopalliance-1.0.jar
commons-logging-1.1.1.jar
spring-aop-3.1.1.RELEASE.jar
spring-asm-3.1.1.RELEASE.jar
spring-beans-3.1.1.RELEASE.jar
spring-context-3.1.1.RELEASE.jar
spring-context-support-3.1.1.RELEASE.jar
spring-core-3.1.1.RELEASE.jar
spring-expression-3.1.1.RELEASE.jar
spring-web-3.1.1.RELEASE.jar
spring-webmvc-3.1.1.RELEASE.jar

Copy and put it in “war/WEB-INF/lib” folder.

Add it to your project’s build path as well – right click on project folder, select “Properties“. Select “Java Build Path” -> “Libraries” tab, click “Add Jars” button and select above jars.

3. Spring Controller

3.1 Delete auto generated SpringMVCGoogleAppEngineServlet.java, you don’t need this.

3.2 Create a bean, act as controller in REST structure. In addition, DI a message into the “message” property.

File : src/com/mkyong/MovieController.java

package com.mkyong.controller;
 
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
 
@Controller
@RequestMapping("/movie")
public class MovieController {
 
	//DI via Spring
	String message;
 
	@RequestMapping(value="/{name}", method = RequestMethod.GET)
	public String getMovie(@PathVariable String name, ModelMap model) {
 
		model.addAttribute("movie", name);
		model.addAttribute("message", this.message);
 
		//return to jsp page, configured in mvc-dispatcher-servlet.xml, view resolver
		return "list";
 
	}
 
	public void setMessage(String message) {
		this.message = message;
	}
 
}

4. JSP Pages

Create a list.jsp page, display the result.

File : war/list.jsp

<html>
<body>
	<h1>GAE + Spring 3 MVC REST example</h1>
 
	<h3>Movie : ${movie} , DI message : ${message}</h3>	
</body>
</html>

5. Spring Configuration

Create a Spring XML bean configuration file, define the beans and view resolver.

File : war/WEB-INF/mvc-dispatcher-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:mvc="http://www.springframework.org/schema/mvc" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="
        http://www.springframework.org/schema/beans     
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
 
	<!-- 
		Need DI a message into controller, so auto component scan is disabled, 
		to avoid double create the movieController bean.
                Only controller need this hack.
	-->
	<context:component-scan base-package="com.mkyong.controller">
		<context:exclude-filter type="regex"
			expression="com.mkyong.controller.Movie.*" />
	</context:component-scan>
 
	<mvc:annotation-driven />
 
	<!-- Bean to show you Di in GAE, via Spring, also init the MovieController -->
	<bean class="com.mkyong.controller.MovieController">
		<property name="message">
			<value>Hello World</value>
		</property>
	</bean>
 
	<bean
	   class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix">
			<value>/pages/</value>
		</property>
		<property name="suffix">
			<value>.jsp</value>
		</property>
	</bean>
 
</beans>

6. web.xml

Update web.xml, integrate Spring framework.

File : war/WEB-INF/web.xml

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
 
	<servlet>
		<servlet-name>mvc-dispatcher</servlet-name>
		<servlet-class>
                    org.springframework.web.servlet.DispatcherServlet
                </servlet-class>
		<load-on-startup>1</load-on-startup>
	</servlet>
 
	<servlet-mapping>
		<servlet-name>mvc-dispatcher</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
 
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value>
	</context-param>
 
	<listener>
		<listener-class>
                    org.springframework.web.context.ContextLoaderListener
                </listener-class>
	</listener>
 
	<welcome-file-list>
		<welcome-file>index.html</welcome-file>
	</welcome-file-list>
</web-app>

7. Directory Structure

Review the final directory structure.

8. Run on Local

Right click on the project, run as “Web Application“.

URL : http://localhost:8888/movie/Avengers

gae spring deploy on local development environemnt

9. Deploy on GAE

Update appengine-web.xml file, add your App Engine application ID.

File : war/WEB-INF/appengine-web.xml

<?xml version="1.0" encoding="utf-8"?>
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
  <application>mkyong-springmvc</application>
  <version>1</version>
 
  <system-properties>
    <property name="java.util.logging.config.file" 
          value="WEB-INF/logging.properties"/>
  </system-properties>
 
</appengine-web-app>