详解如何使用Jersey客户端请求Spring Boot(RESTFul)服务

@Service("jerseyPoolingClient") public class JerseyPoolingClientFactoryBean implements FactoryBean<Client>, InitializingBean, DisposableBean{      /**    * Client接口是REST客户端的基本接口，用于和REST服务器通信。Client被定义为一个重量级的对象，其内部管理着    * 客户端通信底层的各种对象，比如连接器，解析器等。因此，不推荐在应用中产生大量的的Client实例，这一点在开发中    * 需要特别小心，另外该接口要求其实例要有关闭连接的保障，否则会造成内存泄露    */   private Client client;      /**    * 一个Client最大的连接数，默认为2000    */   private int maxTotal = 2000;      /**    * 每路由的默认最大连接数    */   private int defaultMaxPerRoute = 1000;      private ClientConfig clientConfig;      public JerseyPoolingClientFactoryBean() {   }      /**    * 带配置的构造函数    * @param clientConfig    */   public JerseyPoolingClientFactoryBean(ClientConfig clientConfig) {     this.clientConfig = clientConfig;   }    public JerseyPoolingClientFactoryBean(int maxTotal, int defaultMaxPerRoute) {     this.maxTotal = maxTotal;     this.defaultMaxPerRoute = defaultMaxPerRoute;   }    /**    * attention:    * Details：容器销毁时，释放Client资源    * @author chhliu    */   @Override   public void destroy() throws Exception {     this.client.close();   }    /**    *    * attention:    * Details：以连接池的形式，来初始化Client对象    * @author chhliu    */   @Override   public void afterPropertiesSet() throws Exception {     // 如果没有使用带ClientConfig的构造函数，则该类的实例为null，则使用默认的配置初始化     if(this.clientConfig == null){       final ClientConfig clientConfig = new ClientConfig();       // 连接池管理实例，该类是线程安全的，支持多并发操作       PoolingHttpClientConnectionManager pcm = new PoolingHttpClientConnectionManager();       pcm.setMaxTotal(this.maxTotal);       pcm.setDefaultMaxPerRoute(this.defaultMaxPerRoute);              clientConfig.property(ApacheClientProperties.CONNECTION_MANAGER, pcm);       /*        * 在使用Jersey来请求Spring Boot服务时，Spring Boot默认使用Jackson来解析JSON        * 而Jersey默认使用MOXy解析JSON，当Jersey Client想Spring Boot服务请求资源时，        * 这个差异会导致服务端和客户端对POJO的转换不同，造成反序列化的错误        * 因此，此处需要在Client的Config实例中注册Jackson特性        */       clientConfig.register(JacksonFeature.class);       // 使用配置Apache连接器，默认连接器为HttpUrlConnector       clientConfig.connectorProvider(new ApacheConnectorProvider());       client = ClientBuilder.newClient(clientConfig);     }else{       // 使用构造函数中的ClientConfig来初始化Client对象       client = ClientBuilder.newClient(this.clientConfig);     }   }    /**    * attention:    * Details：返回Client对象，如果该对象为null，则创建一个默认的Client    * @author chhliu    */   @Override   public Client getObject() throws Exception {     if(null == this.client){       return ClientBuilder.newClient();     }     return this.client;   }    /**    * attention:    * Details：获取Client对象的类型    * @author chhliu    */   @Override   public Class<?> getObjectType() {     return (this.client == null ? Client.class : this.client.getClass());   }    /**    * attention:    * Details：Client对象是否为单例，默认为单例    * @author chhliu    */   @Override   public boolean isSingleton() {     return true;   } } 

@Component("jerseyClient") public class JerseyClient {      @Resource(name="jerseyPoolingClient")   private Client client;      /**    * attention:    * Details：通过id来查询对象    * @author chhliu    */   public ResultMsg<GitHubEntity> getResponseById(final String id) throws JsonProcessingException, IOException{     WebTarget webTarget = client.target("http://localhost:8080").path("/github/get/user/"+id);     Invocation.Builder invocationBuilder = webTarget.request(MediaType.APPLICATION_JSON);     GenericType<ResultMsg<GitHubEntity>> genericType = new GenericType<ResultMsg<GitHubEntity>>(){};     Response response = invocationBuilder.get();     if(response.getStatus() == 200){       /*        * 当调用readEntity方法时，程序会自动的释放连接        * 即使没有调用readEntity方法，直接返回泛型类型的对象，底层仍然会释放连接        */       return response.readEntity(genericType);     }else{       ResultMsg<GitHubEntity> res = new ResultMsg<GitHubEntity>();       res.setErrorCode(String.valueOf(response.getStatus()));       res.setErrorMsg(response.getStatusInfo().toString());       res.setOK(false);       return res;     }   }      /**    * attention:    * Details：分页查询    * @author chhliu    */   public ResultMsg<Pager<GitHubEntity>> getGithubWithPager(final Integer pageOffset, final Integer pageSize, final String orderColumn){     WebTarget webTarget = client.target("http://localhost:8080").path("/github/get/users/page")         .queryParam("pageOffset", pageOffset)         .queryParam("pageSize", pageSize)         .queryParam("orderColumn", orderColumn);         // 注意，如果此处的媒体类型为MediaType.APPLICATION_JSON，那么对应的服务中的参数前需加上@RequestBody         Invocation.Builder invocationBuilder = webTarget.request(MediaType.APPLICATION_JSON);     GenericType<ResultMsg<Pager<GitHubEntity>>> genericType = new GenericType<ResultMsg<Pager<GitHubEntity>>>(){};     Response response = invocationBuilder.get();     if(response.getStatus() == 200){       return response.readEntity(genericType);     }else{       ResultMsg<Pager<GitHubEntity>> res = new ResultMsg<Pager<GitHubEntity>>();       res.setErrorCode(String.valueOf(response.getStatus()));       res.setErrorMsg(response.getStatusInfo().toString());       res.setOK(false);       return res;     }        }      /**    * attention:    * Details：根据用户名来查询    * @author chhliu    */   public ResultMsg<List<GitHubEntity>> getResponseByUsername(final String username) throws JsonProcessingException, IOException{     WebTarget webTarget = client.target("http://localhost:8080").path("/github/get/users/"+username);     Invocation.Builder invocationBuilder = webTarget.request(MediaType.APPLICATION_JSON);     GenericType<ResultMsg<List<GitHubEntity>>> genericType = new GenericType<ResultMsg<List<GitHubEntity>>>(){};     Response response = invocationBuilder.get();     if(response.getStatus() == 200){       return response.readEntity(genericType);     }else{       ResultMsg<List<GitHubEntity>> res = new ResultMsg<List<GitHubEntity>>();       res.setErrorCode(String.valueOf(response.getStatus()));       res.setErrorMsg(response.getStatusInfo().toString());       res.setOK(false);       return res;     }   }      /**    * attention:    * Details：根据id来删除一个记录    * @author chhliu    */   public ResultMsg<GitHubEntity> deleteById(final String id) throws JsonProcessingException, IOException{     WebTarget target = client.target("http://localhost:8080").path("/github/delete/"+id);     GenericType<ResultMsg<GitHubEntity>> genericType = new GenericType<ResultMsg<GitHubEntity>>(){};     Response response = target.request().delete();     if(response.getStatus() == 200){       return response.readEntity(genericType);     }else{       ResultMsg<GitHubEntity> res = new ResultMsg<GitHubEntity>();       res.setErrorCode(String.valueOf(response.getStatus()));       res.setErrorMsg(response.getStatusInfo().toString());       res.setOK(false);       return res;     }   }      /**    * attention:    * Details：更新一条记录    * @author chhliu    */   public ResultMsg<GitHubEntity> update(final GitHubEntity entity) throws JsonProcessingException, IOException{     WebTarget target = client.target("http://localhost:8080").path("/github/put");     GenericType<ResultMsg<GitHubEntity>> genericType = new GenericType<ResultMsg<GitHubEntity>>(){};     Response response = target.request().buildPut(Entity.entity(entity, MediaType.APPLICATION_JSON)).invoke();     if(response.getStatus() == 200){       return response.readEntity(genericType);     }else{       ResultMsg<GitHubEntity> res = new ResultMsg<GitHubEntity>();       res.setErrorCode(String.valueOf(response.getStatus()));       res.setErrorMsg(response.getStatusInfo().toString());       res.setOK(false);       return res;     }   }      /**    * attention:    * Details：插入一条记录    * @author chhliu    */   public ResultMsg<GitHubEntity> save(final GitHubEntity entity) throws JsonProcessingException, IOException{       WebTarget target = client.target("http://localhost:8080").path("/github/post");      GenericType<ResultMsg<GitHubEntity>> genericType = new GenericType<ResultMsg<GitHubEntity>>(){};      Response response = target.request().buildPost(Entity.entity(entity, MediaType.APPLICATION_JSON)).invoke();      if(response.getStatus() == 200){        return response.readEntity(genericType);      }else{       ResultMsg<GitHubEntity> res = new ResultMsg<GitHubEntity>();       res.setErrorCode(String.valueOf(response.getStatus()));       res.setErrorMsg(response.getStatusInfo().toString());       res.setOK(false);       return res;      }   } } 

StringBuffer sb = new StringBuffer("lch");      sb.append("hello");      sb.append("world");      sb.append("hello").append("world"); // 这种方式和上面的两行代码实现的效果是一样的。 

// 使用一行代码的方法链来实例化WebTarget WebTarget webTarget = client.target("http://localhost:8080"); webTarget.path("/github/get/users/page")   .queryParam("pageOffset", pageOffset)   .queryParam("pageSize", pageSize)   .queryParam("orderColumn", orderColumn); // 下面是分开使用方法链来实例化WebTarget webTarget.path("/github/get/users/page"); webTarget.queryParam("pageOffset", pageOffset); webTarget.queryParam("pageSize", pageSize); // 上面两种实例化的方式最后产生的结果大相径庭，上面的实例化方式是OK的，没有问题，下面的实例化方式却有问题，下面的实例化方式中，每一行都会生成一个 // 新的WebTarget对象，原来的WebTarget并没有起任何作用，毕竟每一行的实例都不一样，如果我们想要分多行实例化了，就必须为每个方法的返回提供一个句柄，方式如下：  WebTarget target = client.target("http://localhost:8080"); WebTarget pathTarget = target.path("/github/get/users/page"); WebTarget paramTarget = pathTarget.queryParam("pageOffset", pageOffset);  // 最后使用的时候，用最后一个WebTarget实例对象即可 

Future<ResultMsg<List<GitHubEntity>>> response = invocationBuilder.async().get(genericType);      if(response.isDone()){       return response.get();     }