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<String,User> userMap  = new HashMap<String,User>();  

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<User> getAllUsers(){       
        List<User> users = new ArrayList<User>();     
        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

本章源码：https://github.com/waylau/RestDemo/tree/master/jersey-demo4-client-curd