三种方法实现调用Restful接口

　　1、基本介绍
　　Restful接口的调用，前端一般使用ajax调用，后端可以使用的方法比较多，
　　本次介绍三种：
　　1）、HttpURLConnection实现
　　2）、HttpClient实现
　　3）、Spring的RestTemplate
　　2、HTTPURLConnection实现 @Controller public class RestfulAction {      @Autowired     private UserService userService;      // 修改     @RequestMapping(value = ＂put/{param}＂, method = RequestMethod.PUT)     public @ResponseBody String put(@PathVariable String param) {         return ＂put:＂ + param;     }      // 新增     @RequestMapping(value = ＂post/{param}＂, method = RequestMethod.POST)     public @ResponseBody String post(@PathVariable String param,String id,String name) {         System.out.println(＂id:＂+id);         System.out.println(＂name:＂+name);         return ＂post:＂ + param;     }      // 删除     @RequestMapping(value = ＂delete/{param}＂, method = RequestMethod.DELETE)     public @ResponseBody String delete(@PathVariable String param) {         return ＂delete:＂ + param;     }      // 查找     @RequestMapping(value = ＂get/{param}＂, method = RequestMethod.GET)     public @ResponseBody String get(@PathVariable String param) {         return ＂get:＂ + param;     }      // HttpURLConnection 方式调用Restful接口     // 调用接口     @RequestMapping(value = ＂dealCon/{param}＂)     public @ResponseBody String dealCon(@PathVariable String param) {         try {             String url = ＂http://localhost:8080/tao-manager-web/＂;             url+=(param+＂/xxx＂);             URL restServiceURL = new URL(url);             HttpURLConnection httpConnection = (HttpURLConnection) restServiceURL                     .openConnection();             //param 输入小写，转换成 GET POST DELETE PUT             httpConnection.setRequestMethod(param.toUpperCase()); //            httpConnection.setRequestProperty(＂Accept＂, ＂application/json＂);             if(＂post＂.equals(param)){                 //打开输出开关                 httpConnection.setDoOutput(true); //                httpConnection.setDoInput(true);                  //传递参数                 String input = ＂&id=＂+ URLEncoder.encode(＂abc＂, ＂UTF-8＂);                 input+=＂&name=＂+ URLEncoder.encode(＂啊啊啊＂, ＂UTF-8＂);                 OutputStream outputStream = httpConnection.getOutputStream();                 outputStream.write(input.getBytes());                 outputStream.flush();             }             if (httpConnection.getResponseCode() != 200) {                 throw new RuntimeException(                         ＂HTTP GET Request Failed with Error code : ＂                                 + httpConnection.getResponseCode());             }             BufferedReader responseBuffer = new BufferedReader(                     new InputStreamReader((httpConnection.getInputStream())));             String output;             System.out.println(＂Output from Server:   ＂);             while ((output = responseBuffer.readLine()) != null) {                 System.out.println(output);             }             httpConnection.disconnect();         } catch (MalformedURLException e) {             e.printStackTrace();         } catch (IOException e) {             e.printStackTrace();         }         return ＂success＂;     }  }
　　3、HttpClient实现 package com.taozhiye.controller;  import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpDelete; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.methods.HttpPut; import org.apache.http.impl.client.HttpClients; import org.apache.http.message.BasicNameValuePair; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.ResponseBody;  import com.fasterxml.jackson.databind.ObjectMapper; import com.taozhiye.entity.User; import com.taozhiye.service.UserService;  import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.net.URLEncoder; import java.util.ArrayList; import java.util.List;  @Controller public class RestfulAction {      @Autowired     private UserService userService;      // 修改     @RequestMapping(value = ＂put/{param}＂, method = RequestMethod.PUT)     public @ResponseBody String put(@PathVariable String param) {         return ＂put:＂ + param;     }      // 新增     @RequestMapping(value = ＂post/{param}＂, method = RequestMethod.POST)     public @ResponseBody User post(@PathVariable String param,String id,String name) {         User u = new User();         System.out.println(id);         System.out.println(name);         u.setName(id);         u.setPassword(name);         u.setEmail(id);         u.setUsername(name);         return u;     }      // 删除     @RequestMapping(value = ＂delete/{param}＂, method = RequestMethod.DELETE)     public @ResponseBody String delete(@PathVariable String param) {         return ＂delete:＂ + param;     }      // 查找     @RequestMapping(value = ＂get/{param}＂, method = RequestMethod.GET)     public @ResponseBody User get(@PathVariable String param) {         User u = new User();         u.setName(param);         u.setPassword(param);         u.setEmail(param);         u.setUsername(＂爱爱啊＂);         return u;     }      @RequestMapping(value = ＂dealCon2/{param}＂)     public @ResponseBody User dealCon2(@PathVariable String param) {         User user = null;         try {             HttpClient client = HttpClients.createDefault();             if(＂get＂.equals(param)){                 HttpGet request = new HttpGet(＂http://localhost:8080/tao-manager-web/get/＂                         +＂啊啊啊＂);                 request.setHeader(＂Accept＂, ＂application/json＂);                 HttpResponse response = client.execute(request);                 HttpEntity entity = response.getEntity();                 ObjectMapper mapper = new ObjectMapper();                 user = mapper.readValue(entity.getContent(), User.class);             }else if(＂post＂.equals(param)){                 HttpPost request2 = new HttpPost(＂http://localhost:8080/tao-manager-web/post/xxx＂);                 List nvps = new ArrayList();                 nvps.add(new BasicNameValuePair(＂id＂, ＂啊啊啊＂));                 nvps.add(new BasicNameValuePair(＂name＂, ＂secret＂));                 UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(nvps, ＂GBK＂);                 request2.setEntity(formEntity);                 HttpResponse response2 = client.execute(request2);                 HttpEntity entity = response2.getEntity();                 ObjectMapper mapper = new ObjectMapper();                 user = mapper.readValue(entity.getContent(), User.class);             }else if(＂delete＂.equals(param)){              }else if(＂put＂.equals(param)){              }         } catch (Exception e) {             e.printStackTrace();         }         return user;     } }
　　4、String的RestTemplate实现
　　springmvc.xml增加                                                          
　　controller@Controller public class RestTemplateAction {      @Autowired     private RestTemplate template;      @RequestMapping(＂RestTem＂)     public @ResponseBody User RestTem(String method) {         User user = null;         //查找         if (＂get＂.equals(method)) {             user = template.getForObject(                     ＂http://localhost:8080/tao-manager-web/get/{id}＂,                     User.class, ＂呜呜呜呜＂);              //getForEntity与getForObject的区别是可以获取返回值和状态、头等信息             ResponseEntity re = template.                     getForEntity(＂http://localhost:8080/tao-manager-web/get/{id}＂,                     User.class, ＂呜呜呜呜＂);             System.out.println(re.getStatusCode());             System.out.println(re.getBody().getUsername());          //新增         } else if (＂post＂.equals(method)) {             HttpHeaders headers = new HttpHeaders();             headers.add(＂X-Auth-Token＂, UUID.randomUUID().toString());             MultiValueMap postParameters = new LinkedMultiValueMap();             postParameters.add(＂id＂, ＂啊啊啊＂);             postParameters.add(＂name＂, ＂部版本＂);             HttpEntity> requestEntity = new HttpEntity>(                     postParameters, headers);             user = template.postForObject(                     ＂http://localhost:8080/tao-manager-web/post/aaa＂, requestEntity,                     User.class);         //删除         } else if (＂delete＂.equals(method)) {             template.delete(＂http://localhost:8080/tao-manager-web/delete/{id}＂,＂aaa＂);         //修改         } else if (＂put＂.equals(method)) {             template.put(＂http://localhost:8080/tao-manager-web/put/{id}＂,null,＂bbb＂);         }         return user;      } }