HttpClient 用法详细介绍

偏执的太偏执、 2023-06-27 15:57 65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：

  1. <dependencies>
  3.     <!-- web场景 -->
  4.     <dependency>
  5.         <groupId>org.springframework.boot</groupId>
  6.         <artifactId>spring-boot-starter-web</artifactId>
  7.     </dependency>
  9.     <!-- jpa场景 -->
  10.     <dependency>
  11.         <groupId>org.springframework.boot</groupId>
  12.         <artifactId>spring-boot-starter-data-jpa</artifactId>
  13.     </dependency>
  15.     <!-- mysql驱动 -->
  16.     <dependency>
  17.         <groupId>mysql</groupId>
  18.         <artifactId>mysql-connector-java</artifactId>
  19.         <version>8.0.18</version>
  20.     </dependency>
  22.     <!-- 单元测试 -->
  23.     <dependency>
  24.         <groupId>org.springframework.boot</groupId>
  25.         <artifactId>spring-boot-starter-test</artifactId>
  26.         <scope>test</scope>
  27.     </dependency>
  29.     <!-- HttpClient的依赖(httpmime依赖包含了httpclient以及httpcore) -->
  30.     <dependency>
  31.         <groupId>org.apache.httpcomponents</groupId>
  32.         <artifactId>httpmime</artifactId>
  33.     </dependency>
  35.     <!-- 早期引入如下两个依赖 -->
  36. <!-- <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpcore</artifactId> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> </dependency> -->
  38.     <!-- 文件上传下载 -->
  39.     <dependency>
  40.         <groupId>commons-fileupload</groupId>
  41.         <artifactId>commons-fileupload</artifactId>
  42.         <version>1.3.3</version>
  43.     </dependency>
  44. </dependencies>

2.2 application.properties：

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

2.3 实体类：

  1. @Entity
  2. @Table(name = "user")
  3. public class User implements Serializable { 
  5.     @Id
  6.     @GeneratedValue(strategy = GenerationType.IDENTITY)
  7.     private Integer id;
  9.     @Column
  10.     private String username;
  12.     @Column
  13.     private Date birthday;
  15.     @Column
  16.     private String pic;
  18.     // 省略get/set....
  19. }

2.4 dao：

  1. public interface UserDao extends JpaRepository<User,Integer> { 
  2. }

2.5 controller：

  1. @RestController
  2. @RequestMapping("/user")
  3. public class UserController { 
  5.     @Autowired
  6.     private UserDao userDao;
  8.     /** * 添加用户 * @param user * @return * @throws Exception */
  9.     @PostMapping
  10.     public Map save(@RequestBody User user) throws Exception { 
  11.         user.setBirthday(new Date());
  12.         userDao.save(user);
  13.         Map returnMap = new HashMap<>();
  14.         returnMap.put("message", "添加成功");
  16.         return returnMap;
  17.     }
  19.     /** * 删除用户 * @param id * @return */
  20.     @DeleteMapping("/{id}")
  21.     public Map delete(@PathVariable Integer id) { 
  23.         userDao.deleteById(id);
  25.         Map returnMap = new HashMap<>();
  26.         returnMap.put("message", "删除成功");
  27.         return returnMap;
  28.     }
  30.     /** * 修改用户 * @param id * @param user * @return */
  31.     @PutMapping("/{id}")
  32.     public Map update(@PathVariable Integer id, @RequestBody User user) { 
  34.         user.setId(id);
  35.         userDao.save(user);
  37.         Map returnMap = new HashMap<>();
  38.         returnMap.put("message", "修改成功");
  39.         return returnMap;
  40.     }
  42.     /** * 根据id查询用户 * @param id * @return */
  43.     @GetMapping("/{id}")
  44.     public User findById(@PathVariable Integer id) { 
  45.         return userDao.findById(id).get();
  46.     }
  48.     /** * 查询全部用户 * @return */
  49.     @GetMapping
  50.     public List<User> findAll() { 
  51.         return userDao.findAll();
  52.     }
  54.     /** * 上传头像 * * @param pic * @param username * @return * @throws Exception */
  55.     @PostMapping("/upload")
  56.     // 如果上传了多个文件使用：List<MultipartFile> pic
  57.     public Map upload(MultipartFile pic, String username) throws Exception { 
  59.         pic.transferTo(new File("D:\\", UUID.randomUUID().toString() + ".png"));
  61.         Map returnMap = new HashMap<>();
  62.         returnMap.put("message", "上传成功");
  63.         returnMap.put("data", username);
  64.         return returnMap;
  65.     }
  66. }

2.6 启动类：

  1. @SpringBootApplication
  2. public class HttpclientApplication { 
  4.     public static void main(String[] args) { 
  5.         SpringApplication.run(HttpclientApplication.class, args);
  6.     }
  8. }

数据库脚本如下：

  1. CREATE TABLE `user`  (
  2.   `id` int(11) NOT NULL AUTO_INCREMENT,
  3.   `username` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  4.   `birthday` datetime(0) NULL DEFAULT NULL,
  5.   `pic` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  6.   PRIMARY KEY (`id`) USING BTREE
  7. ) 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

  1. @Test
  2. public void test1() throws Exception{ 
  4.     // 获取HttpClient实例
  5.     CloseableHttpClient httpClient = HttpClients.createDefault();
  7.     // 创建一个HttpGet请求
  8.     HttpGet httpGet = new HttpGet("http://localhost:8080/user");
  10.     // 发送请求,获取响应结果
  11.     CloseableHttpResponse response = httpClient.execute(httpGet);
  13.     // 获取响应实体
  14.     HttpEntity responseEntity = response.getEntity();
  16.     System.out.println("响应状态: " + response.getStatusLine());
  17.     if (responseEntity != null) { 
  18.         System.out.println("响应内容长度为:" + responseEntity.getContentLength());
  19.         System.out.println("响应内容为:" + EntityUtils.toString(responseEntity));
  20.     }
  21. }

在这里插入图片描述

3.1.2 Get请求带参数

  • 请求代码：

    @Test
    public void test2() throws Exception { 

    1. // 获取HttpClient实例
    2. CloseableHttpClient httpClient = HttpClients.createDefault();
    4. // 请求参数
    5. StringBuilder params = new StringBuilder();
    6. params.append("?");
    7. // 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)
    8. params.append("username=" + URLEncoder.encode("admin", "UTF8"));
    10. HttpGet httpGet = new HttpGet("http://localhost:8080/user/testGet" + params);
    12. // 发送请求,获取响应结果
    13. CloseableHttpResponse response = httpClient.execute(httpGet);
    15. // 获取响应实体
    16. HttpEntity responseEntity = response.getEntity();
    18. System.out.println("响应状态: " + response.getStatusLine());
    19. if (responseEntity != null) { 
    20.     System.out.println("响应内容长度为:" + responseEntity.getContentLength());
    21.     System.out.println("响应内容为:" + EntityUtils.toString(responseEntity));
    22. }

    }

  • 新增接口：

    @GetMapping(“/testGet”)
    public Map testGet(String username) throws Exception{ 

    1. Map returnMap = new HashMap<>();
    2. returnMap.put("message", "请求成功");
    3. returnMap.put("data", username);
    4. 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 { 

    1. // 获取HttpClient实例
    2. CloseableHttpClient httpClient = HttpClients.createDefault();
    4. // 将参数放入键值对类NameValuePair中,再放入集合中
    5. List<NameValuePair> params = new ArrayList<>();
    6. params.add(new BasicNameValuePair("username", "admin"));
    8. // 设置uri信息,并将参数集合放入uri;
    9. // 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)
    10. URI uri = new URIBuilder().setScheme("http").setHost("localhost")
    11.         .setPort(8080).setPath("/user/testGet")
    12.         .setParameters(params).build();
    14. HttpGet httpGet = new HttpGet(uri);
    16. print(httpClient, httpGet);

    }

3.1.4 抽取打印方法

  1. /** * 抽取打印方法 * * @param httpClient * @param http * @throws Exception */
  2. private void print(CloseableHttpClient httpClient, HttpRequestBase http) throws Exception { 
  3.     // 发送请求,获取响应结果
  4.     CloseableHttpResponse response = httpClient.execute(http);
  6.     // 获取响应实体
  7.     HttpEntity responseEntity = response.getEntity();
  9.     System.out.println("响应状态: " + response.getStatusLine());
  10.     if (responseEntity != null) { 
  11.         System.out.println("响应内容长度为:" + responseEntity.getContentLength());
  13.         // 设置响应内容的编码（默认为UTF8）
  14.         System.out.println("响应内容为:" + EntityUtils.toString(responseEntity, "UTF8"));
  15.     }
  17.     response.close();
  18.     httpClient.close();
  19. }

3.2 Post请求

3.2.1 普通Post请求

  • 请求代码：

    @Test
    public void test4() throws Exception { 

    1. // 获取HttpClient实例
    2. CloseableHttpClient httpClient = HttpClients.createDefault();
    4. HttpPost httpPost = new HttpPost("http://localhost:8080/user/testPost");
    6. print(httpClient, httpPost);

    }

  • 请求接口：

    @PostMapping(“/testPost”)
    public Map testPost() throws Exception { 

    1. Map returnMap = new HashMap<>();
    2. returnMap.put("message", "普通方式post请求成功");
    3. return returnMap;

    }

3.2.2 Post请求带参数

  • 请求代码：

    @Test
    public void test5() throws Exception { 

    1. // 获取HttpClient实例
    2. CloseableHttpClient httpClient = HttpClients.createDefault();
    4. HttpPost httpPost = new HttpPost("http://localhost:8080/user/testPost?username=admin");
    6. print(httpClient, httpPost);

    }

  • 新增接口

    @PostMapping(“/testPost2”)
    public Map testPost2(String username) throws Exception { 

    1. Map returnMap = new HashMap<>();
    2. returnMap.put("message", "普通方式post请求成功");
    3. returnMap.put("data", username);
    4. return returnMap;

    }

3.2.3 Post请求提交对象

  1. @Test
  2. public void test6() throws Exception { 
  3.     // 获取HttpClient实例
  4.     CloseableHttpClient httpClient = HttpClients.createDefault();
  6.     User user=new User();
  7.     user.setUsername("王五");
  9.     // json转换工具
  10.     ObjectMapper om = new ObjectMapper();
  11.     StringEntity entity = new StringEntity(om.writeValueAsString(user), "utf-8");
  13.     HttpPost httpPost = new HttpPost("http://localhost:8080/user");
  15.     // 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
  16.     httpPost.setEntity(entity);
  18.     // 设置请求头
  19.     httpPost.setHeader("Content-Type", "application/json;charset=utf8");
  20.     httpClient.execute(httpPost);
  22.     print(httpClient, httpPost);
  24. }

3.2.4 Post请求对象+参数

  • 请求代码：

    @Test
    public void test7() throws Exception { 

    1. // 获取HttpClient实例
    2. CloseableHttpClient httpClient = HttpClients.createDefault();
    4. User user=new User();
    5. user.setUsername("赵六");
    7. // json转换工具
    8. ObjectMapper om = new ObjectMapper();
    9. StringEntity entity = new StringEntity(om.writeValueAsString(user), "utf-8");
    11. // 构建uri
    12. URI uri = new URIBuilder().setScheme("http").setHost("localhost")
    13.         .setPort(8080).setPath("/user/testPost")
    14.         .setParameter("flag", "测试post请求带参哦！")       //使用setParameter设置单个参数
    15.         .build();
    17. HttpPost httpPost = new HttpPost(uri);
    19. // 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
    20. httpPost.setEntity(entity);
    22. // 设置请求头
    23. httpPost.setHeader("Content-Type", "application/json;charset=utf8");
    24. httpClient.execute(httpPost);
    26. print(httpClient, httpPost);

    }

  • 新增接口：

    @PostMapping(“/testPost3”)
    public Map testPost3(@RequestBody User user, String flag) throws Exception { 

    1. user.setBirthday(new Date());
    2. userDao.save(user);
    3. Map returnMap = new HashMap<>();
    4. returnMap.put("message", "请求testPost3成功");
    5. returnMap.put("data", flag);
    7. return returnMap;

    }

3.3 Put请求

  1. @Test
  2. public void test8() throws Exception { 
  3.     // 获取HttpClient实例
  4.     CloseableHttpClient httpClient = HttpClients.createDefault();
  6.     User user=new User();
  7.     user.setUsername("管理员");
  9.     ObjectMapper om=new ObjectMapper();
  10.     String userStr = om.writeValueAsString(user);
  11.     // 构建实体
  12.     StringEntity entity = new StringEntity(userStr, StandardCharsets.UTF_8);
  14.     HttpPut httpPut = new HttpPut("http://localhost:8080/user/12");
  16.     // 设置请求头
  17.     httpPut.setHeader("Content-Type", "application/json;charset=utf8");
  18.     httpPut.setEntity(entity);
  20.     httpClient.execute(httpPut);
  22.     print(httpClient,httpPut);
  23. }

3.4 Delete请求

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

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 { 

    1. // 获取HttpClient实例
    2. CloseableHttpClient httpClient = HttpClients.createDefault();
    4. HttpPost httpPost = new HttpPost("http://localhost:8080/user/testForm");
    6. // 设置请求头
    7. httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");
    9. List<BasicNameValuePair> params = new ArrayList<>();
    10. params.add(new BasicNameValuePair("id","100"));
    11. params.add(new BasicNameValuePair("username","张三"));
    12. // 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())));

    1. params.add(new BasicNameValuePair("pic","https://www.baidu.com/favicon.ico"));
    3. // 构建一个虚拟表单,并设置参数
    4. UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params,StandardCharsets.UTF_8);
    6. // 设置请求实体
    7. httpPost.setEntity(entity);
    9. // 发送请求
    10. httpClient.execute(httpPost);
    12. 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 { 

    1. Map returnMap = new HashMap<>();
    2. returnMap.put("message", "请求testForm成功");
    3. returnMap.put("data", user);
    5. return returnMap;

    }

4.2 上传文件

注：

  1. <dependency>
  2.     <groupId>org.apache.httpcomponents</groupId>
  3.     <artifactId>httpmime</artifactId>
  4. </dependency>
  6. @Test
  7. public void test11() throws Exception { 
  8.     // 获取HttpClient实例
  9.     CloseableHttpClient httpClient = HttpClients.createDefault();
  11.     MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create();
  13.     // 可以添加多个图片(name保持一致就行,后台使用List<MultipartFile> pic接收)
  14. // multipartEntityBuilder.addBinaryBody("pic",new File("D:\\10.png"));
  15.     multipartEntityBuilder.addBinaryBody("pic",new File("D:\\11.png"));
  17.     // 携带文本参数
  18.     multipartEntityBuilder.addTextBody("username","管理员", ContentType.create("text/plain",StandardCharsets.UTF_8));
  20.     // 装换为HttpEntity
  21.     HttpEntity entity = multipartEntityBuilder.build();
  23.     HttpPost httpPost = new HttpPost("http://localhost:8080/user/upload");
  25.     httpPost.setEntity(entity);
  27.     print(httpClient,httpPost);
  29. }

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 { 

    1. // 获取HttpClient实例
    2. CloseableHttpClient httpClient = HttpClients.createDefault();
    4. InputStream is = new ByteArrayInputStream("admin".getBytes());
    6. // 构建数据流实体
    7. InputStreamEntity entity = new InputStreamEntity(is);
    9. HttpPost httpPost = new HttpPost("http://localhost:8080/user/testStream");
    11. httpPost.setEntity(entity);
    13. // 发送请求
    14. httpClient.execute(httpPost);
    16. 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 { 

    1. // 接受前端传递的数据
    2. String str = new BufferedReader(new InputStreamReader(is)).readLine();
    3. Map returnMap = new HashMap<>();
    4. returnMap.put("message", "testStream");
    5. returnMap.put("data", str);
    7. return returnMap;

    }

发表评论

表情：
评论列表 （有 0 条评论，65人围观）

还没有评论，来说两句吧...

相关阅读