HttpClient 用法详细介绍

偏执的太偏执、 2023-06-27 15:57 1阅读 0赞

# 一、简介 #

超文本传输协议（HTTP）可能是当今Internet上使用的最重要的协议。Web服务，具有网络功能的设备以及网络计算的增长继续将HTTP协议的作用扩展到用户驱动的Web浏览器之外，同时增加了需要HTTP支持的应用程序的数量。尽管java.net 软件包提供了用于通过HTTP访问资源的基本功能，但它并未提供许多应用程序所需的全部灵活性或功能。Jakarta Commons HttpClient 组件试图通过提供高效，最新且功能丰富的程序包来实现此空白，以实现最新HTTP标准和建议的客户端。

Commons HttpClient项目现已停产，并且不再开发。它已被其HttpClient和HttpCore模块中的Apache HttpComponents项目取代。

# 二、项目搭建 #

tips：本项目案例是基于SpringBoot+SpringDataJPA环境搭建的

## 2.1 导入依赖： ##

<dependencies>
    
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
    
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>
    
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    
        
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpmime</artifactId>
        </dependency>
    
        
    
    
        
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.3</version>
        </dependency>
    </dependencies>

## 2.2 application.properties： ##

server.port=8080
    
    # 数据源配置
    spring.datasource.username=root
    spring.datasource.password=admin
    spring.datasource.driver-class-name=com.mysql.jdbc.Driver
    spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test?serverTimezone=GMT%2b8
    
    # jpa配置
    spring.jpa.show-sql=true
    spring.jpa.database=mysql

## 2.3 实体类： ##

@Entity
    @Table(name = "user")
    public class User implements Serializable { 
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Integer id;
    
        @Column
        private String username;
    
        @Column
        private Date birthday;
    
        @Column
        private String pic;
    
    	// 省略get/set....
    }

## 2.4 dao： ##

public interface UserDao extends JpaRepository<User,Integer> { 
    }

## 2.5 controller： ##

@RestController
    @RequestMapping("/user")
    public class UserController { 
    
        @Autowired
        private UserDao userDao;
    
        /** * 添加用户 * @param user * @return * @throws Exception */
        @PostMapping
        public Map save(@RequestBody User user) throws Exception { 
            user.setBirthday(new Date());
            userDao.save(user);
            Map returnMap = new HashMap<>();
            returnMap.put("message", "添加成功");
    
            return returnMap;
        }
    
        /** * 删除用户 * @param id * @return */
        @DeleteMapping("/{id}")
        public Map delete(@PathVariable Integer id) { 
    
            userDao.deleteById(id);
    
            Map returnMap = new HashMap<>();
            returnMap.put("message", "删除成功");
            return returnMap;
        }
    
        /** * 修改用户 * @param id * @param user * @return */
        @PutMapping("/{id}")
        public Map update(@PathVariable Integer id, @RequestBody User user) { 
    
            user.setId(id);
            userDao.save(user);
    
            Map returnMap = new HashMap<>();
            returnMap.put("message", "修改成功");
            return returnMap;
        }
    
        /** * 根据id查询用户 * @param id * @return */
        @GetMapping("/{id}")
        public User findById(@PathVariable Integer id) { 
            return userDao.findById(id).get();
        }
    
        /** * 查询全部用户 * @return */
        @GetMapping
        public List<User> findAll() { 
            return userDao.findAll();
        }
    
    	/** * 上传头像 * * @param pic * @param username * @return * @throws Exception */
    	@PostMapping("/upload")
    	// 如果上传了多个文件使用：List<MultipartFile> pic
    	public Map upload(MultipartFile pic, String username) throws Exception { 
    	
    	    pic.transferTo(new File("D:\\", UUID.randomUUID().toString() + ".png"));
    	
    	    Map returnMap = new HashMap<>();
    	    returnMap.put("message", "上传成功");
    	    returnMap.put("data", username);
    	    return returnMap;
    	}
    }

## 2.6 启动类： ##

@SpringBootApplication
    public class HttpclientApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(HttpclientApplication.class, args);
        }
    
    }

数据库脚本如下：

CREATE TABLE `user`  (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `username` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
      `birthday` datetime(0) NULL DEFAULT NULL,
      `pic` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
      PRIMARY KEY (`id`) USING BTREE
    ) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

本人已亲测，controller所有接口均可用。大家可以跟我一样，先把环境搭建好

# 三、HttpClient快速入门 #

## 3.1 Get 请求 ##

### 3.1.1 普通Get请求 ###

@Test
    public void test1() throws Exception{ 
    
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        // 创建一个HttpGet请求
        HttpGet httpGet = new HttpGet("http://localhost:8080/user");
    
        // 发送请求,获取响应结果
        CloseableHttpResponse response = httpClient.execute(httpGet);
    
        // 获取响应实体
        HttpEntity responseEntity = response.getEntity();
    
        System.out.println("响应状态: " + response.getStatusLine());
        if (responseEntity != null) { 
            System.out.println("响应内容长度为:" + responseEntity.getContentLength());
            System.out.println("响应内容为:" + EntityUtils.toString(responseEntity));
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JiMTUwNzAwNDc3NDg_size_16_color_FFFFFF_t_70]

### 3.1.2 Get请求带参数 ###

*  请求代码：

@Test
    public void test2() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        // 请求参数
        StringBuilder params = new StringBuilder();
        params.append("?");
        // 字符数据最好encoding一下;这样一来，某些特殊字符才能传过去(如:username就是"&",不encoding的话,解析时,会认为要拼接下一个参数username就为空)
        params.append("username=" + URLEncoder.encode("admin", "UTF8"));
    
        HttpGet httpGet = new HttpGet("http://localhost:8080/user/testGet" + params);
    
        // 发送请求,获取响应结果
        CloseableHttpResponse response = httpClient.execute(httpGet);
    
        // 获取响应实体
        HttpEntity responseEntity = response.getEntity();
    
        System.out.println("响应状态: " + response.getStatusLine());
        if (responseEntity != null) { 
            System.out.println("响应内容长度为:" + responseEntity.getContentLength());
            System.out.println("响应内容为:" + EntityUtils.toString(responseEntity));
        }
    }

*  新增接口：

@GetMapping("/testGet")
    public Map testGet(String username) throws Exception{ 
    
        Map returnMap = new HashMap<>();
        returnMap.put("message", "请求成功");
        returnMap.put("data", username);
        return returnMap;
    }

### 3.1.3 GET请求使用URI方式 ###

使用URIBuilder()来构建一个uri对象用于传递参数使用。

URIBuilder()中有如下方法

*  `setParameters(List<NameValuePair> params)`：用于构建多个键值对，使用List，单个NameValuePair用于封装一个键值对
 *  `setParameter(String key,String val)`：自己手动添加键值对

// GET请求(使用URI获取HttpGet)
    @Test
    public void test3() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        // 将参数放入键值对类NameValuePair中,再放入集合中
        List<NameValuePair> params = new ArrayList<>();
        params.add(new BasicNameValuePair("username", "admin"));
    
        // 设置uri信息,并将参数集合放入uri;
        // 注:这里也支持一个键值对一个键值对地往里面放setParameter(String key, String value)
        URI uri = new URIBuilder().setScheme("http").setHost("localhost")
                .setPort(8080).setPath("/user/testGet")
                .setParameters(params).build();
    
        HttpGet httpGet = new HttpGet(uri);
    
        print(httpClient, httpGet);
    }

### 3.1.4 抽取打印方法 ###

/** * 抽取打印方法 * * @param httpClient * @param http * @throws Exception */
    private void print(CloseableHttpClient httpClient, HttpRequestBase http) throws Exception { 
        // 发送请求,获取响应结果
        CloseableHttpResponse response = httpClient.execute(http);
    
        // 获取响应实体
        HttpEntity responseEntity = response.getEntity();
    
        System.out.println("响应状态: " + response.getStatusLine());
        if (responseEntity != null) { 
            System.out.println("响应内容长度为:" + responseEntity.getContentLength());
    		
    		// 设置响应内容的编码（默认为UTF8）
            System.out.println("响应内容为:" + EntityUtils.toString(responseEntity, "UTF8"));
        }
    
        response.close();
        httpClient.close();
    }

## 3.2 Post请求 ##

### 3.2.1 普通Post请求 ###

*  请求代码：

@Test
    public void test4() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        HttpPost httpPost = new HttpPost("http://localhost:8080/user/testPost");
    
        print(httpClient, httpPost);
    
    }

*  请求接口：

@PostMapping("/testPost")
    public Map testPost() throws Exception { 
    
        Map returnMap = new HashMap<>();
        returnMap.put("message", "普通方式post请求成功");
        return returnMap;
    }

### 3.2.2 Post请求带参数 ###

*  请求代码：

@Test
    public void test5() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        HttpPost httpPost = new HttpPost("http://localhost:8080/user/testPost?username=admin");
    
        print(httpClient, httpPost);
    
    }

*  新增接口

@PostMapping("/testPost2")
    public Map testPost2(String username) throws Exception { 
    
        Map returnMap = new HashMap<>();
        returnMap.put("message", "普通方式post请求成功");
        returnMap.put("data", username);
        return returnMap;
    }

### 3.2.3 Post请求提交对象 ###

@Test
    public void test6() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        User user=new User();
        user.setUsername("王五");
    
        // json转换工具
        ObjectMapper om = new ObjectMapper();
        StringEntity entity = new StringEntity(om.writeValueAsString(user), "utf-8");
    
        HttpPost httpPost = new HttpPost("http://localhost:8080/user");
    
        // post请求是将参数放在请求体里面传过去的;这里将entity放入post请求体中
        httpPost.setEntity(entity);
    
        // 设置请求头
        httpPost.setHeader("Content-Type", "application/json;charset=utf8");
        httpClient.execute(httpPost);
    
        print(httpClient, httpPost);
    
    }

### 3.2.4 Post请求对象+参数 ###

*  请求代码：

@Test
    public void test7() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        User user=new User();
        user.setUsername("赵六");
    
        // json转换工具
        ObjectMapper om = new ObjectMapper();
        StringEntity entity = new StringEntity(om.writeValueAsString(user), "utf-8");
    
        // 构建uri
        URI uri = new URIBuilder().setScheme("http").setHost("localhost")
                .setPort(8080).setPath("/user/testPost")
                .setParameter("flag", "测试post请求带参哦！")       //使用setParameter设置单个参数
                .build();
    
        HttpPost httpPost = new HttpPost(uri);
    
        // post请求是将参数放在请求体里面传过去的;这里将entity放入post请求体中
        httpPost.setEntity(entity);
    
        // 设置请求头
        httpPost.setHeader("Content-Type", "application/json;charset=utf8");
        httpClient.execute(httpPost);
    
        print(httpClient, httpPost);
    
    }

*  新增接口：

@PostMapping("/testPost3")
    public Map testPost3(@RequestBody User user, String flag) throws Exception { 
        user.setBirthday(new Date());
        userDao.save(user);
        Map returnMap = new HashMap<>();
        returnMap.put("message", "请求testPost3成功");
        returnMap.put("data", flag);
    
        return returnMap;
    }

## 3.3 Put请求 ##

@Test
    public void test8() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        User user=new User();
        user.setUsername("管理员");
    
        ObjectMapper om=new ObjectMapper();
        String userStr = om.writeValueAsString(user);
        // 构建实体
        StringEntity entity = new StringEntity(userStr, StandardCharsets.UTF_8);
    
        HttpPut httpPut = new HttpPut("http://localhost:8080/user/12");
    
        // 设置请求头
        httpPut.setHeader("Content-Type", "application/json;charset=utf8");
        httpPut.setEntity(entity);
    
        httpClient.execute(httpPut);
    
        print(httpClient,httpPut);
    }

## 3.4 Delete请求 ##

@Test
    public void test9() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        HttpDelete httpDelete = new HttpDelete("http://localhost:8080/user/12");
    
        httpClient.execute(httpDelete);
    
        print(httpClient,httpDelete);
    
    }

# 四、特殊类型请求 #

## 4.1 模拟表单提交 ##

*  4.1.1 请求代码：

@Test
    public void test10() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        HttpPost httpPost = new HttpPost("http://localhost:8080/user/testForm");
    
        // 设置请求头
        httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");
    
        List<BasicNameValuePair> params = new ArrayList<>();
        params.add(new BasicNameValuePair("id","100"));
        params.add(new BasicNameValuePair("username","张三"));
        // 这里不要传递birthday,后台需要定义converter,做类型转换(String->Date),你们有兴趣自己去玩,也不难
    // params.add(new BasicNameValuePair("birthday",new SimpleDateFormat("yyyy-MM-dd").format(new Date())));
        params.add(new BasicNameValuePair("pic","https://www.baidu.com/favicon.ico"));
    
        // 构建一个虚拟表单,并设置参数
        UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params,StandardCharsets.UTF_8);
    
        // 设置请求实体
        httpPost.setEntity(entity);
    
        // 发送请求
        httpClient.execute(httpPost);
    
        print(httpClient, httpPost);
    
    }

*  4.1.2 新增接口：

/** * 测试表单传输 * @param user * @return * @throws Exception */
    @PostMapping("/testForm")
    public Map testPost3(User user) throws Exception { 
        Map returnMap = new HashMap<>();
        returnMap.put("message", "请求testForm成功");
        returnMap.put("data", user);
    
        return returnMap;
    }

## 4.2 上传文件 ##

注：

<dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpmime</artifactId>
    </dependency>

@Test
    public void test11() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create();
    
        // 可以添加多个图片(name保持一致就行,后台使用List<MultipartFile> pic接收)
    // multipartEntityBuilder.addBinaryBody("pic",new File("D:\\10.png"));
        multipartEntityBuilder.addBinaryBody("pic",new File("D:\\11.png"));
    
        // 携带文本参数
        multipartEntityBuilder.addTextBody("username","管理员", ContentType.create("text/plain",StandardCharsets.UTF_8));
    
        // 装换为HttpEntity
        HttpEntity entity = multipartEntityBuilder.build();
    
        HttpPost httpPost = new HttpPost("http://localhost:8080/user/upload");
    
        httpPost.setEntity(entity);
    
        print(httpClient,httpPost);
    
    }

## 4.3 传递数据流 ##

*  4.3.1 请求代码：

// 发送数据流
    @Test
    public void test12() throws Exception { 
        // 获取HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
    
        InputStream is = new ByteArrayInputStream("admin".getBytes());
    
        // 构建数据流实体
        InputStreamEntity entity = new InputStreamEntity(is);
    
        HttpPost httpPost = new HttpPost("http://localhost:8080/user/testStream");
    
        httpPost.setEntity(entity);
    
        // 发送请求
        httpClient.execute(httpPost);
    
        print(httpClient,httpPost);
    
    }

*  4.3.2 新增接口：

/** * 测试数据流传输 * * @param is * @return * @throws Exception */
    @PostMapping(value = "/testStream")
    public Map testStream(InputStream is) throws Exception { 
        // 接受前端传递的数据
        String str = new BufferedReader(new InputStreamReader(is)).readLine();
        Map returnMap = new HashMap<>();
        returnMap.put("message", "testStream");
        returnMap.put("data", str);
    
        return returnMap;
    }

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