Spring and RESTEasy ~ TECHIE KERNEL

This tutorial I am going to demonstrate how to integrate Jboss RESTEasy and Spring 3 to create a RESTFul web service. Using this I am going to show how use spring context to get the service bean in web service class.

I am going to use the following tools and technologies.

Jersey 2.2.1.GA
Spring 3.0.5.RELEASE
JDK 1.7
Tomcat 7.0
Maven
Eclipse

I am going to take you to the following areas in this tutorial.

Service Layer Interface
Service Layer Class
Web Service Class
Spring Bean Configuration
Configuration for Spring and RESTEasy
Application Deployment
Testing

Before start coding let's create a dynamic web project using the following maven command.

1	mvn archetype:generate -DgroupId=com.techiekernel.rest -DartifactId=Spring-RESTEasy -DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false

After executing, the project will be get created with pom.xml file. As I am using JDK 7 and annotations, I have to specify the updated maven plugin. After giving the RESTEasy and Spring dependency, the pom.xml looks as following.

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.techiekernel.rest</groupId>
  <artifactId>Spring-RESTEasy</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>JAXRS-Jersey Maven Webapp</name>
  <url>http://maven.apache.org</url>

  <repositories>
    <repository>
      <id>JBoss repository</id>
      <url>https://repository.jboss.org/nexus/content/groups/public-jboss/</url>
    </repository>
  </repositories>
 
  <dependencies>
 
    <!-- JBoss RESTEasy -->
    <dependency>
      <groupId>org.jboss.resteasy</groupId>
      <artifactId>resteasy-jaxrs</artifactId>
      <version>2.2.1.GA</version>
    </dependency>
 
    <!-- Spring 3 dependencies -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>3.0.5.RELEASE</version>
    </dependency>
 
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>3.0.5.RELEASE</version>
    </dependency>
 
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>3.0.5.RELEASE</version>
    </dependency>
 
    <!-- need for solution 1, if your container don't have this -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.4</version>
    </dependency>
    </dependencies>
    <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.1.1</version>
      </plugin>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.5</source>
          <target>1.5</target>
        </configuration>
      </plugin>
    </plugins>
    <finalName>Spring-RESTEasy</finalName>
  </build>
</project>

Service Layer Interface:

package com.techiekernel.service;

public interface FooBarService {
  public String getMessage(String msg);
}

Service Layer Class:

package com.techiekernel.service;

public class FooBarServiceImpl implements FooBarService{
  public String getMessage(String msg) {
    String output = "FooBar say : " + msg;
    return output;
  }
}

Web Service Class:

package com.techiekernel.rest;

import javax.servlet.ServletContext;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.Response;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component;
import org.springframework.web.context.support.WebApplicationContextUtils;

import com.techiekernel.service.FooBarService;

@Component
@Path("/foobar")
public class FooBarWS {
  FooBarService fooBarService;
 
  @GET
  @Path("/{param}")
  public Response getMessage(@PathParam("param") String msg, @Context ServletContext servletContext) {
    //get Spring application context
        ApplicationContext ctx = 
                         WebApplicationContextUtils.getWebApplicationContext(servletContext);
        fooBarService= ctx.getBean("FooBar",FooBarService.class);
    return Response.status(200).entity(fooBarService.getMessage(msg)).build();
  }
}

Using the spring context to get the bean in stead of IOC does not look good to me. I suggest you to check this post for better integration. I followed the example, but that did not work for me.. So I end up doing this mess. But I strongly suggest to give a try to this post.

Spring Bean Configuration:

Now it is time to create the configuration for spring beans in applicationContext.xml. It is very much required to place the following configuration in classpath, so that container will read from the deployment descriptor.

<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
  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">

  <context:component-scan base-package="com.techiekernel.rest" />

  <bean id="FooBar" class="com.techiekernel.service.FooBarServiceImpl" />

</beans>

Configuration for Spring and RESTEasy:

The integration is going to be in web.xml. Register Spring “ContextLoaderListener” listener class and specify the RESTEasy servlet “org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher“ as front controller for web services.

<web-app id="WebApp_ID" version="2.4"
  xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
  http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <display-name>Spring RESTEasy</display-name>

  <context-param>
    <param-name>resteasy.resources</param-name>
    <param-value>com.techiekernel.rest.FooBarWS</param-value>
  </context-param>
 
  <listener>
    <listener-class>
      org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
                </listener-class>
  </listener>
 
  <listener>
    <listener-class>
                        org.springframework.web.context.ContextLoaderListener
                </listener-class>
  </listener>
 
 <!-- this need same with resteasy servlet url-pattern -->
  <context-param>
    <param-name>resteasy.servlet.mapping.prefix</param-name>
    <param-value>/ws</param-value>
  </context-param>
  <servlet>
    <servlet-name>resteasy-servlet</servlet-name>
    <servlet-class>
      org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher
                </servlet-class>
  </servlet>
 
  <servlet-mapping>
    <servlet-name>resteasy-servlet</servlet-name>
    <url-pattern>/ws/*</url-pattern>
  </servlet-mapping>
</web-app>

Application Deployment:

Now every thing is ready and time to build for creating a war file.

1	mvn clean install;

n successful completion of the above command a war file will be get created in target folder. Copy the war file to webapp folder of your tomcat and start the tomcat.

Testing:

Once tomcat is started use the following url to access the web service.

1	http://localhost:8080/Spring-RESTEasy/ws/foobar/techiekernel

Once you hit the url in the browser, you are going to get the following output.

1	FooBar say : techiekernel

Source Code:

You can pull the code from GitHub.

TECHIE KERNEL

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Thursday, December 13, 2012

Spring and RESTEasy

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