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  • Java 调用RESTful接口的几种方式

    前端一般通过Ajax来调用,后端调用的方式还是挺多的,比如HttpURLConnection,HttpClient,Spring的RestTemplate

    服务端代码如下:

    服务端接口请求的URL:http://localhost:8080/rest/user/getUser/xiaoming/18,设定请求方式为GET

    package com.demo.restful.service.impl;
     
    import com.demo.restful.model.User;
    import com.demo.restful.service.UserService;
     
    import javax.ws.rs.GET;
    import javax.ws.rs.Path;
    import javax.ws.rs.PathParam;
    import javax.ws.rs.Produces;
    import javax.ws.rs.core.MediaType;
     
    /**
     * @Author: 
     * @Date: 2019/1/8 11:37
     */
    @Path("user")
    public class UserServiceImpl implements UserService {
     
        @Override
        @GET
        @Path("getUser/{name}/{age}")
        @Produces(MediaType.APPLICATION_JSON)
        public String getUser(@PathParam("name") String name,@PathParam("age") Integer age) {
            return new User(name,age).toString();
        }
    }
    

      

    客户端的三种请求方式如下:

    注:以下demo都是以GET请求为例

    1.HttpURLConnection(首先需要引入httpclient包)

    <dependency>
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpclient</artifactId>
       <version>4.5.6</version>
    </dependency>
    

      测试代码 

    package com.demo.restful;
     
    import java.io.BufferedReader;
    import java.io.InputStreamReader;
    import java.net.HttpURLConnection;
    import java.net.URL;
     
    /**
     * @Author: 
     * @Date: 2019/1/9 11:12
     */
    public class HttpUrlConnectionTest {
        public static void main(String[] args) throws Exception {
            String url = "http://localhost:8080/rest/user/getUser/xiaoming/18";
            URL serverUrl = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) serverUrl.openConnection();
            connection.setRequestMethod("GET");
            if (connection.getResponseCode() != 200) {
                throw new RuntimeException(
                        "HTTP GET Request Failed with Error code : "
                                + connection.getResponseCode());
            }
            BufferedReader responseBuffer = new BufferedReader(
                    new InputStreamReader((connection.getInputStream())));
            String output;
            System.out.println("Output from Server:  
    ");
            while ((output = responseBuffer.readLine()) != null) {
                System.out.println(output);
            }
            connection.disconnect();
        }
    } 
    

      

    测试结果


    2.HttpClient(首先需要引入httpclient包,POM同上)

    测试代码

    package com.demo.restful;
     
    import org.apache.http.HttpEntity;
    import org.apache.http.HttpResponse;
    import org.apache.http.client.HttpClient;
    import org.apache.http.client.methods.HttpGet;
    import org.apache.http.impl.client.HttpClients;
     
    import java.io.BufferedReader;
    import java.io.InputStreamReader;
    import java.util.stream.Collectors;
     
    /**
     * @Author: 
     * @Date: 2019/1/9 11:42
     */
    public class HttpClientTest {
     
        public static void main(String[] args) throws Exception {
            HttpClient httpClient = HttpClients.createDefault();
            HttpGet httpGet = new HttpGet("http://localhost:8080/rest/user/getUser/xiaoming/18");
     
            HttpResponse execute = httpClient.execute(httpGet);
            HttpEntity entity = execute.getEntity();
            System.out.println(entity);
            String result = new BufferedReader(new InputStreamReader(entity.getContent()))
                    .lines().collect(Collectors.joining("
    "));
            System.out.println(result);
        }
    } 
    

      

    测试结果


    3.RestTemplate(首先需要引入spring-webmvc包)

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-web -->
    <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-webmvc</artifactId>
       <version>5.1.3.RELEASE</version>
    </dependency> 
    

      

    测试代码

    第一步:配置web.xml

    <web-app>
      <display-name>Archetype Created Web Application</display-name>
      <servlet>
        <servlet-name>restful-client</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>spring.xml</param-value>
        </init-param>
      </servlet>
      <servlet-mapping>
        <servlet-name>restful-client</servlet-name>
        <url-pattern>/</url-pattern>
      </servlet-mapping>
    </web-app> 
    

      

    第二步:配置Spring注解扫描

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <!-- 启用注解 -->
    <context:component-scan base-package="com.demo.restful.controller"/>
    </beans> 
    

    第三步:编写controller

    package com.demo.restful.controller;
     
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.context.annotation.Bean;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.*;
    import org.springframework.web.client.RestTemplate;
     
    /**
     * @Author: 
     * @Date: 2019/1/9 14:56
     */
    @Controller
    public class RestTemplateController {
     
        @Autowired
        private RestTemplate restTemplate;
        
        //手动将RestTemplate加入Spring容器中
        @Bean
        public RestTemplate restTemplate(){
            return new RestTemplate();
        }
     
        @RequestMapping("/getUser.json")
        @ResponseBody
        public String getUser(){
            String url = "http://localhost:8080/rest/user/getUser/xiaoming/18";
            String forObject = restTemplate.getForObject(url, String.class);
            return forObject;
        }
    } 
    

      

    浏览器运行结果

     

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  • 原文地址:https://www.cnblogs.com/guohu/p/12192659.html
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