一、总体说明

通过jersey-client接口，创建客户端程序，来调用Jersey实现的RESTful服务，实现增、删、改、查等操作。服务端主要是通过内存的方式，来模拟用户的增加、删除、修改、查询等操作。

二、创建服务端

1.在上文项目中，在“com.waylau.rest.resources.UserResource“中修改代码，首先创建一个HashMap，用来保存添加的用户

private static Map
    
      userMap  = new HashMap
     
      ();

2.创建增、删、改、查用户资源等操作

/**      * 增加      * @param user      */      @POST      @Consumes({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})      public void createStudent(User user)      {          userMap.put(user.getUserId(), user );      }      /**      * 删除      * @param id      */      @DELETE      @Path("{id}")      public void deleteStudent(@PathParam("id")String id){          userMap.remove(id);      }      /**      * 修改      * @param user      */      @PUT      @Consumes(MediaType.APPLICATION_XML)      public void updateStudent(User user){          userMap.put(user.getUserId(), user );      }      /**      * 根据id查询      * @param id      * @return      */      @GET      @Path("{id}")      @Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})      public User getUserById(@PathParam("id") String id){          User u = userMap.get(id);          return u;      }      /**      * 查询所有      * @return      */      @GET      @Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})      public List
    
      getAllUsers(){               List
     
       users = new ArrayList
      
       ();             users.addAll( userMap.values() );            return users;      }

三、创建客户端程序

1.创建包“com.waylau.rest.client”，在包下建一个UserClient.java，代码如下：

package com.waylau.rest.client;      import javax.ws.rs.client.Client;      import javax.ws.rs.client.ClientBuilder;      import javax.ws.rs.client.Entity;      import javax.ws.rs.client.WebTarget;      import javax.ws.rs.core.MediaType;      import javax.ws.rs.core.Response;      import org.codehaus.jackson.jaxrs.JacksonJsonProvider;      import com.waylau.rest.bean.User;      /**      * 用户客户端，用来测试资源      * @author waylau.com      * 2014-3-18      */      public class UserClient {          private static String serverUri = "http://localhost:8089/RestDemo/rest";          /**          * @param args          */          public static void main(String[] args) {              addUser();              getAllUsers();              updateUser();              getUserById();              getAllUsers();              delUser();              getAllUsers();          }          /**          * 添加用户          */           private static void addUser() {               System.out.println("****增加用户addUser****");               User user = new User("006","Susan","21");                 Client client = ClientBuilder.newClient();               WebTarget target = client.target(serverUri + "/users");               Response response = target.request().buildPost(Entity.entity(user, MediaType.APPLICATION_XML)).invoke();               response.close();          }          /**          * 删除用户          */           private static void delUser() {               System.out.println("****删除用户****");               Client client = ClientBuilder.newClient();               WebTarget target = client.target(serverUri + "/users/006");               Response response = target.request().delete();               response.close();          }          /**          * 修改用户          */           private static void updateUser() {               System.out.println("****修改用户updateUser****");               User user = new User("006","Susan","33");                 Client client = ClientBuilder.newClient();               WebTarget target = client.target(serverUri + "/users");               Response response = target.request().buildPut( Entity.entity(user, MediaType.APPLICATION_XML)).invoke();               response.close();          }          /**          * 根据id查询用户          */           private static void getUserById() {               System.out.println("****根据id查询用户****");               Client client = ClientBuilder.newClient().register(JacksonJsonProvider.class);// 注册json 支持               WebTarget target = client.target(serverUri + "/users/006");               Response response = target.request().get();               User user = response.readEntity(User.class);               System.out.println(user.getUserId() + user.getUserName()  +  user.getAge());               response.close();          }          /**          * 查询所有用户          */           private static void getAllUsers() {               System.out.println("****查询所有getAllUsers****");               Client client = ClientBuilder.newClient();               WebTarget target = client.target(serverUri + "/users");               Response response = target.request().get();               String value = response.readEntity(String.class);               System.out.println(value);               response.close();  //关闭连接           }      }

四、运行

启动服务端项目，运行客户端程序UserClient，控制台输出如下

****增加用户addUser****  ****查询所有getAllUsers****  [{
   "userId":"006","userName":"Susan","age":"21"}]  ****修改用户updateUser****  ****根据id查询用户****  006Susan33  ****查询所有getAllUsers****  [{
   "userId":"006","userName":"Susan","age":"33"}]  ****删除用户****  ****查询所有getAllUsers****  []

五、总结

1.客户端如果需要进行JSON转换，需要进行JSON注册

Client client = ClientBuilder.newClient().register(JacksonJsonProvider.class);

2.WebTarget 指明了要请求的资源的地址

3.target.request(). 后面跟的是请求的方法:POST，GET，PUT或DELETE

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