pring RestTemplate: 比httpClient更优雅的Restful URL访问

 {
   "Author": "tomcat and jerry",
   "url":"http://www.cnblogs.com/tomcatandjerry/p/5899722.html"
 }

spring RestTemplate, 使用Java访问URL更加优雅，更加方便。

核心代码：

 String url = "http://localhost:8080/json";
 JSONObject json = restTemplate.getForEntity(url, JSONObject.class).getBody();

就这么简单，API访问完成了！

附上SpringBoot相关的完整代码：

 RestTemplateConfig.java

 @Configuration
 public class RestTemplateConfig{
     @Bean
     public RestTemplate restTemplate(ClientHttpRequestFactory factory){
         return new RestTemplate(factory);
     }

     @Bean
     public ClientHttpRequestFactory simpleClientHttpRequestFactory(){
         SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
         factory.setReadTimeout(5000);//ms
         factory.setConnectTimeout(15000);//ms
         return factory;
     }
 }

 SpringRestTemplateApp.java
 @RestController
 @EnableAutoConfiguration
 @Import(value = {Conf.class})
 public class SpringRestTemplateApp {

     @Autowired
     RestTemplate restTemplate;

     /***********HTTP GET method*************/
     @RequestMapping("")
     public String hello(){
         String url = "http://localhost:8080/json";
         JSONObject json = restTemplate.getForEntity(url, JSONObject.class).getBody();
         return json.toJSONString();
     }

     @RequestMapping("/json")
     public Object genJson(){
         JSONObject json = new JSONObject();
         json.put("descp", "this is spring rest template sample");
         return json;
     }

     /**********HTTP POST method**************/
     @RequestMapping("/postApi")
     public Object iAmPostApi(@RequestBody JSONObject parm){
         System.out.println(parm.toJSONString());
         parm.put("result", "hello post");
         return parm;
     }

     @RequestMapping("/post")
     public Object testPost(){
         String url = "http://localhost:8080/postApi";
         JSONObject postData = new JSONObject();
         postData.put("descp", "request for post");
         JSONObject json = restTemplate.postForEntity(url, postData, JSONObject.class).getBody();
         return json.toJSONString();
     }

     public static void main(String[] args) throws Exception {
         SpringApplication.run(SpringRestTemplateApp.class, args);
     }

 }

===============================

另外还支持异步调用AsyncRestTemplate

 @RequestMapping("/async")
     public String asyncReq(){
         String url = "http://localhost:8080/jsonAsync";
         ListenableFuture> future = asyncRestTemplate.getForEntity(url, JSONObject.class);
         future.addCallback(new SuccessCallback>() {
             public void onSuccess(ResponseEntity result) {
                 System.out.println(result.getBody().toJSONString());
             }
         }, new FailureCallback() {
             public void onFailure(Throwable ex) {
                 System.out.println("onFailure:"+ex);
             }
         });
         return "this is async sample";
     }

 ================================

贴一段post请求如何自定义header

 @RequestMapping("/headerApi")//模拟远程的restful API
     public JSONObject withHeader(@RequestBody JSONObject parm, HttpServletRequest req){
         System.out.println("headerApi====="+parm.toJSONString());
         Enumeration headers = req.getHeaderNames();
         JSONObject result = new JSONObject();
         while(headers.hasMoreElements()){
             String name = headers.nextElement();
             System.out.println("["+name+"]="+req.getHeader(name));
             result.put(name, req.getHeader(name));
         }
         result.put("descp", "this is from header");
         return result;
     }

     @RequestMapping("/header")
     public Object postWithHeader(){
 　　　　//该方法通过restTemplate请求远程restfulAPI
         HttpHeaders headers = new HttpHeaders();
         headers.set("auth_token", "asdfgh");
         headers.set("Other-Header", "othervalue");
         headers.setContentType(MediaType.APPLICATION_JSON);

         JSONObject parm = new JSONObject();
         parm.put("parm", "1234");
         HttpEntity entity = new HttpEntity(parm, headers);
         HttpEntity response = restTemplate.exchange(
                 "http://localhost:8080/headerApi", HttpMethod.POST, entity, String.class);//这里放JSONObject, String 都可以。因为JSONObject返回的时候其实也就是string
         return response.getBody();
     }