RESTEasy Tutorial Part-1: Basics

 <project xmlns='http:maven.apache.orgPOM4.0.0' 
   xmlns:xsi='http:www.w3.org2001XMLSchema-instance'
   xsi:schemaLocation='http:maven.apache.orgPOM4.0.0 
   http:maven.apache.orgmaven-v4_0_0.xsd'>
   <modelVersion>4.0.0<modelVersion> 
 
   <groupId>com.sivalabs<groupId>
   <artifactId>resteasy-demo<artifactId>
   <version>0.1<version>  
   <packaging>war<packaging>
   <name>resteasy-demo Maven Webapp<name>
     
   <build>
     <finalName>resteasy-demo<finalName>
   <build>
   
   <dependencies>
   
     <dependency>
       <groupId>junit<groupId>
       <artifactId>junit<artifactId>
    <version>4.8.2<version>
       <scope>test<scope>
     <dependency>
 
     <dependency>
      <groupId>org.jboss.resteasy<groupId>
      <artifactId>resteasy-jaxrs<artifactId>
   <version>2.3.2.FINAL<version>
      <scope>provided<scope>
     <dependency>
 
     <dependency>
      <groupId>org.jboss.resteasy<groupId>
      <artifactId>resteasy-jaxb-provider<artifactId>
   <version>2.3.2.FINAL<version>
      <scope>provided<scope>
     <dependency>
 
     <dependency>
      <groupId>org.jboss.resteasy<groupId>
      <artifactId>jaxrs-api<artifactId>
      <version>2.3.0.GA<version>
      <scope>provided<scope>
     <dependency>
  <dependency>
         <groupId>org.apache.httpcomponents<groupId>
         <artifactId>httpclient<artifactId>
         <version>4.1.2<version>
   <scope>provided<scope>
     <dependency>
   <dependencies>
   
 <project>

Step#2: Configure RESTEasy in web.xml

 <web-app xmlns:xsi='http:www.w3.org2001XMLSchema-instance' 
   xmlns='http:java.sun.comxmlnsjavaee' 
   xmlns:web='http:java.sun.comxmlnsjavaeeweb-app_2_5.xsd' 
   xsi:schemaLocation='http:java.sun.comxmlnsjavaee 
   http:java.sun.comxmlnsjavaeeweb-app_3_0.xsd' 
   id='WebApp_ID' version='3.0'>
 
   <listener>
     <listener-class>org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap<listener-class>
   <listener>
   <servlet>
     <servlet-name>Resteasy<servlet-name>
     <servlet-class>org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher<servlet-class>
   <servlet>
   <servlet-mapping>
     <servlet-name>Resteasy<servlet-name>
     <url-pattern>rest*<url-pattern>
   <servlet-mapping>
   <context-param>
     <param-name>resteasy.servlet.mapping.prefix<param-name>
     <param-value>rest<param-value>
   <context-param>
   <context-param>
         <param-name>resteasy.scan<param-name>
         <param-value>true<param-value>
     <context-param>
 <web-app>

Step#3: Create User domain class, MockUserTable class to store User objects in-memory for testing purpose and UserResource class to expose CRUD operations on User as RESTful webservices.

 package com.sivalabs.resteasydemo;
 
 import java.util.Date;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.XmlRootElement;
 
 @XmlRootElement
 @XmlAccessorType(XmlAccessType.FIELD)
 public class User 
 {
  private Integer id;
  private String name;
  private String email;
  private Date dob;
  setters and getters
 }
 
 
 package com.sivalabs.resteasydemo;
 
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 import com.sivalabs.resteasydemo.User;
 
 public class MockUserTable 
 {
 
  private static Map<Integer, User> USER_MAP = new HashMap<Integer, User>();
  static
  {
   USER_MAP.put(1, new User(1,'admin','admin@gmail.com',new Date()));
   USER_MAP.put(2, new User(2,'test','test@gmail.com',new Date()));
  }
 
  public static void save(User user){
   USER_MAP.put(user.getId(), user);
  }
 
  public static User getById(Integer id){
   return USER_MAP.get(id);
  }
 
  public static List<User> getAll(){
   List<User> users = new ArrayList<User>(USER_MAP.values());
   return users;
  }
  public static void delete(Integer id){
   USER_MAP.remove(id);
  } 
 }
 
 
 package com.sivalabs.resteasydemo;
 
 import java.util.List;
 
 import javax.ws.rs.DELETE;
 import javax.ws.rs.GET;
 import javax.ws.rs.POST;
 import javax.ws.rs.Path;
 import javax.ws.rs.PathParam;
 import javax.ws.rs.Produces;
 import javax.ws.rs.core.GenericEntity;
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.Response;
 
 import com.sivalabs.resteasydemo.MockUserTable;
 
 @Path('users')
 @Produces(MediaType.APPLICATION_XML)
 public class UserResource 
 {
 
  @Path('')
  @GET
  public Response getUsersXML() 
  {
   List<User> users = MockUserTable.getAll();
   GenericEntity<List<User>> ge = new GenericEntity<List<User>>(users){};
   return Response.ok(ge).build();
  }
 
  @Path('{id}')
  @GET
  public Response getUserXMLById(@PathParam('id') Integer id) {
   return Response.ok(MockUserTable.getById(id)).build();
  }
 
  @Path('')
  @POST
  public Response saveUser(User user) {
   MockUserTable.save(user);
   return Response.ok('<status>success<status>').build();
  }
 
  @Path('{id}')
  @DELETE
  public Response deleteUser(@PathParam('id') Integer id) {
   MockUserTable.delete(id);
   return Response.ok('<status>success<status>').build();
  }
 
 }

Step#6: JUnit TestCase to test the REST Webservice.

 package com.sivalabs.resteasydemo;
 
 import java.util.List;
 
 import org.jboss.resteasy.client.ClientRequest;
 import org.jboss.resteasy.client.ClientResponse;
 import org.jboss.resteasy.util.GenericType;
 import org.junit.Assert;
 import org.junit.Test;
 
 import com.sivalabs.resteasydemo.User;
 
 public class UserResourceTest {
 
  static final String ROOT_URL = 'http:localhost:8080resteasy-demorest';
 
  @Test
  public void testGetUsers() throws Exception 
  {
   ClientRequest request = new ClientRequest(ROOT_URL+'users');
   ClientResponse<List<User>> response = request.get(new GenericType<List<User>>(){});
   List<User> users = response.getEntity();
   Assert.assertNotNull(users);
  }
 
  @Test
  public void testGetUserById() throws Exception 
  {
   ClientRequest request = new ClientRequest(ROOT_URL+'users1');
   ClientResponse<User> response = request.get(User.class);
   User user = response.getEntity();
   Assert.assertNotNull(user);
  }
 
  @Test
  public void testSaveUser() throws Exception 
  {
   User user = new User();
   user.setId(3);
   user.setName('User3');
   user.setEmail('user3@gmail.com');
 
   ClientRequest request = new ClientRequest(ROOT_URL+'users');
   request.body('applicationxml', user);
   ClientResponse<String> response = request.post(String.class);
 
   String statusXML = response.getEntity();
   Assert.assertNotNull(statusXML);
  }
 
  @Test
  public void testDeleteUser() throws Exception 
  {
   ClientRequest request = new ClientRequest(ROOT_URL+'users2');
   ClientResponse<String> response = request.delete(String.class);
   String statusXML = response.getEntity();
   Assert.assertNotNull(statusXML);
  }
 }

Step#7: To test the REST service we can use the REST Client Tool.
You can download REST Client Tool at http://code.google.com/a/eclipselabs.org/p/restclient-tool/

Important Things to Keep in mind:
1. org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap Listener should be registered before any other listener.

2. You should configure resteasy.servlet.mapping.prefix <context-param> if the HttpServletDispatcher servlet url-pattern is anything other than /*

Continue to the second part of this tutorial.

Reference: RESTEasy Tutorial Part-1: Basics from our JCG partner Siva Reddy at the My Experiments on Technology blog.