java调用Restful接口的三种方法

目录

• 1,基本介绍

• 2，HttpURLConnection实现

• 3.HttpClient实现

• 4.Spring的RestTemplate

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:  \n");
           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<NameValuePair> nvps = new ArrayList<NameValuePair>();  
               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.Spring的RestTemplate

springmvc.xml增加

<!-- 配置RestTemplate -->
   <!--Http client Factory -->
   <bean id="httpClientFactory"
       class="org.springframework.http.client.SimpleClientHttpRequestFactory">
       <property name="connectTimeout" value="10000" />
       <property name="readTimeout" value="10000" />
   </bean>

<!--RestTemplate -->
   <bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
       <constructor-arg ref="httpClientFactory" />
   </bean>

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<User> 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<String, String> postParameters = new LinkedMultiValueMap<String, String>();
           postParameters.add("id", "啊啊啊");
           postParameters.add("name", "部版本");
           HttpEntity<MultiValueMap<String, String>> requestEntity = new HttpEntity<MultiValueMap<String, String>>(
                   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;

}
}

来源：https://www.cnblogs.com/yuluoxingkong/p/8818538.html