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You have learned that how to write the RESTful web services and also how to write Spring 3 web application. Now, its time to combine them so that your spring web application shall work like RESTful webservices also.

Download source code

For writing this application, I am modifying the source code written in previous post. So, if want, you can download from there or you have it from above download link.

Step 1) Update pom.xml to add support of JAXB and Jackson (for xml and json formats).

	<dependency>
      <groupid>org.codehaus.jackson</groupid>
      <artifactid>jackson-mapper-asl</artifactid>
      <version>${jackson-mapper-asl.version}</version>
      <scope>runtime</scope>
	</dependency>

	<dependency>
      <groupid>javax.xml.bind</groupid>
      <artifactid>jaxb-api</artifactid>
      <version>${jaxb-api.version}</version>
      <scope>runtime</scope>
	</dependency>

Do not forget to run “mvn eclipse:eclipse -Dwtpversion=2.0” command on command prompt again, to update the project dependencies.

Step 2) Update bean configuration file (spring-mvc-servlet.xml) for view resolvers.

<mvc:annotation-driven />

<context:component-scan  base-package="com.howtodoinjava.web" />

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
	<property name="mediaTypes">
	  <map>
		  <entry key="html" value="text/html"></entry>
		  <entry key="json" value="application/json"></entry>
		  <entry key="xml"  value="application/xml"></entry>
	  </map>
	</property>
	 <property name="viewResolvers">
		<list>
		  <bean class="org.springframework.web.servlet.view.UrlBasedViewResolver">
			<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"></property>
			<property name="prefix" value="/WEB-INF/jsp/"></property>
			<property name="suffix" value=".jsp"></property>
		  </bean>
		</list>
	</property>
</bean>

Step 3) Add model classes I am writing 2 classes i.e. Users.java and User.java. These classes will be having JAXB annotations, which will be used by marshaller to convert them in appropriate xml or json formats. They are for example only and you can write your own classes.

package com.howtodoinjava.model;

import java.util.Collection;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="users")
@XmlAccessorType(XmlAccessType.NONE)
public class Users
{
	@XmlElement(name="user")
	private Collection<User> users;

	public Collection<User> getUsers() {
		return users;
	}

	public void setUsers(Collection<User> users) {
		this.users = users;
	}
}

Now write User.java.

package com.howtodoinjava.model;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="user")
@XmlAccessorType(XmlAccessType.NONE)
public class User {

	@XmlElement(name="first-name")
	private String firstName;

	@XmlElement(name="last-name")
	private String lastName;

	public String getFirstName() {
		return firstName;
	}
	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
}

Step 4) Update the controller Our DemoController.java will modified to have REST specific annotations for path mappings in request parameters mappings. Also, we will specify the header attributes for request and response.

@Controller
@RequestMapping("/users")
public class DemoController
{
	@RequestMapping(method = RequestMethod.GET, value="/{id}", headers="Accept=*/*")
	public @ResponseBody User getUserById(@PathVariable String id)
	{
		User user = new User();
		user.setFirstName("john");
		user.setLastName("adward");
		return user;
	}

	@RequestMapping(method = RequestMethod.GET,  headers="Accept=*/*")
	public @ResponseBody Users getAllUsers()
	{
		User user1 = new User();
		user1.setFirstName("john");
		user1.setLastName("adward");

		User user2 = new User();
		user2.setFirstName("tom");
		user2.setLastName("hanks");

		Users users = new Users();
		users.setUsers(new ArrayList<User>());
		users.getUsers().add(user1);
		users.getUsers().add(user2);

		return users;
	}
}

Now lets re-deploy the application on tomcat and hit the URL on any REST client. I am using RESTClient. This is a firefox plugin for testing the RESTful webservices.

URL : http://localhost:8080/firstSpringApplication/users

URL : http://localhost:8080/firstSpringApplication/users/123

Download source code

Drop me a comment if it really helped you, or you have any query.

Happy Leaning !!