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本文 Github.com/niumoo/JavaNotes 和 未读代码博客 已经收录，有很多知识点和系列文章。

超文本传输协议（HTTP）可能是当今互联网上最重要的协议之一，Web 服务、微服务以及支持网络的各种设备上的服务几乎都是 HTTP 协议，HTTP 协议已经从 Web 浏览器走向了更广泛的使用场景。

虽然 java.net 包已经提供了 HTTP 访问资源的基本功能，但是它不够灵活，而且不能随心所欲的进行自定义。Apache HttpClient 5 是一个开源的 HTTP 工具包，可以支持最新 HTTP 协议标准，且有丰富的 API 和强大的扩展特性，可以用于构建任何需要进行 HTTP 协议处理的应用程序。

这篇文章介绍 Apache HttpClient 5 中最为常见的一些用法，通过这篇文章可以快速的入门使用 HttpClient 5，主要内容包括 HttpClient 5 的 Get 请求、Post 请求、如何携带参数、JSON 参数、设置超时、异步请求、操作 Cookie、表单登录、基本认证、Digest 认证以及自定义 HTTP 请求拦截器等。

HttpClient 5 依赖

HttpClient 5 Maven 依赖

  1. <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents.client5/httpclient5 -->
  2. <dependency>
  3.     <groupId>org.apache.httpcomponents.client5</groupId>
  4.     <artifactId>httpclient5</artifactId>
  5.     <version>5.1.3</version>
  6. </dependency>
  7. <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents.client5/httpclient5-fluent -->
  8. <dependency>
  9.     <groupId>org.apache.httpcomponents.client5</groupId>
  10.     <artifactId>httpclient5-fluent</artifactId>
  11.     <version>5.1.3</version>
  12. </dependency>

HttpClient 5 Gradle 依赖

  1. implementation 'org.apache.httpcomponents.client5:httpclient5:5.1.3'
  2. implementation 'org.apache.httpcomponents.client5:httpclient5-fluent:5.1.3'

HttpClient 5 GET 请求

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  5. import org.apache.hc.client5.http.classic.methods.HttpGet;
  6. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  7. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  8. import org.apache.hc.client5.http.impl.classic.HttpClients;
  9. import org.apache.hc.core5.http.HttpEntity;
  10. import org.apache.hc.core5.http.ParseException;
  11. import org.apache.hc.core5.http.io.entity.EntityUtils;
  13. /**
  14.  * @author https://www.wdbyte.com
  15.  */
  16. public class HttpClient5Get {
  18.     public static void main(String[] args) {
  19.         String result = get("http://httpbin.org/get");
  20.         System.out.println(result);
  21.     }
  23.     public static String get(String url) {
  24.         String resultContent = null;
  25.         HttpGet httpGet = new HttpGet(url);
  26.         try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
  27.             try (CloseableHttpResponse response = httpclient.execute(httpGet)) {
  28.                 // 获取状态码
  29.                 System.out.println(response.getVersion()); // HTTP/1.1
  30.                 System.out.println(response.getCode()); // 200
  31.                 System.out.println(response.getReasonPhrase()); // OK
  32.                 HttpEntity entity = response.getEntity();
  33.                 // 获取响应信息
  34.                 resultContent = EntityUtils.toString(entity);
  35.             }
  36.         } catch (IOException | ParseException e) {
  37.             e.printStackTrace();
  38.         }
  39.         return resultContent;
  40.     }
  42. }

响应信息：

  1. HTTP/1.1
  2. 200
  3. OK
  4. {
  5.   "args": {},
  6.   "headers": {
  7.     "Accept-Encoding": "gzip, x-gzip, deflate",
  8.     "Host": "httpbin.org",
  9.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/17)",
  10.     "X-Amzn-Trace-Id": "Root=1-62bb1891-5ab5e5376ed960471bf32f17"
  11.   },
  12.   "origin": "47.251.4.198",
  13.   "url": "http://httpbin.org/get"
  14. }

HttpClient 5 Fluent GET

使用 Apache HttpClient 5 提供的 Fluent API 可以更便捷的发起 GET 请求，但是可操作的地方较少。

依赖：

  1. <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents.client5/httpclient5-fluent -->
  2. <dependency>
  3.     <groupId>org.apache.httpcomponents.client5</groupId>
  4.     <artifactId>httpclient5-fluent</artifactId>
  5.     <version>5.1.3</version>
  6. </dependency>

示例：

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  5. import org.apache.hc.client5.http.fluent.Request;
  6. import org.apache.hc.client5.http.fluent.Response;
  8. /**
  9. * @author https://www.wdbyte.com
  10.  */
  11. public class HttpClient5GetFluent {
  13.     public static void main(String[] args) {
  14.         System.out.println(get("http://httpbin.org/get"));
  15.     }
  17.     public static String get(String url) {
  18.         String result = null;
  19.         try {
  20.             Response response = Request.get(url).execute();
  21.             result = response.returnContent().asString();
  22.         } catch (IOException e) {
  23.             e.printStackTrace();
  24.         }
  25.         return result;
  26.     }
  28. }

输出信息：

  1. {
  2.   "args": {},
  3.   "headers": {
  4.     "Accept-Encoding": "gzip, x-gzip, deflate",
  5.     "Host": "httpbin.org",
  6.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/17)",
  7.     "X-Amzn-Trace-Id": "Root=1-62bb190e-1ba46a92645843a04c55da32"
  8.   },
  9.   "origin": "47.251.4.198",
  10.   "url": "http://httpbin.org/get"
  11. }

HttpClient5 GET 请求参数

使用 URIBuilder 的 addParameters() 方法来构建 GET 请求的参数。

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  4. import java.net.URI;
  5. import java.net.URISyntaxException;
  6. import java.util.ArrayList;
  7. import java.util.List;
  9. import org.apache.hc.client5.http.classic.methods.HttpGet;
  10. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  11. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  12. import org.apache.hc.client5.http.impl.classic.HttpClients;
  13. import org.apache.hc.core5.http.HttpEntity;
  14. import org.apache.hc.core5.http.NameValuePair;
  15. import org.apache.hc.core5.http.ParseException;
  16. import org.apache.hc.core5.http.io.entity.EntityUtils;
  17. import org.apache.hc.core5.http.message.BasicNameValuePair;
  18. import org.apache.hc.core5.net.URIBuilder;
  20. /**
  21. * @author https://www.wdbyte.com
  22.  */
  23. public class HttpClient5GetParams {
  25.     public static void main(String[] args) {
  26.         String result = get("http://httpbin.org/get");
  27.         System.out.println(result);
  28.     }
  30.     public static String get(String url) {
  31.         String resultContent = null;
  32.         HttpGet httpGet = new HttpGet(url);
  33.         // 表单参数
  34.         List<NameValuePair> nvps = new ArrayList<>();
  35.         // GET 请求参数
  36.         nvps.add(new BasicNameValuePair("username", "wdbyte.com"));
  37.         nvps.add(new BasicNameValuePair("password", "secret"));
  38.         // 增加到请求 URL 中
  39.         try {
  40.             URI uri = new URIBuilder(new URI(url))
  41.                 .addParameters(nvps)
  42.                 .build();
  43.             httpGet.setUri(uri);
  44.         } catch (URISyntaxException e) {
  45.             throw new RuntimeException(e);
  46.         }
  48.         try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
  49.             try (CloseableHttpResponse response = httpclient.execute(httpGet)) {
  50.                 // 获取状态码
  51.                 System.out.println(response.getVersion()); // HTTP/1.1
  52.                 System.out.println(response.getCode()); // 200
  53.                 System.out.println(response.getReasonPhrase()); // OK
  54.                 HttpEntity entity = response.getEntity();
  55.                 // 获取响应信息
  56.                 resultContent = EntityUtils.toString(entity);
  57.             }
  58.         } catch (IOException | ParseException e) {
  59.             e.printStackTrace();
  60.         }
  61.         return resultContent;
  62.     }
  63. }

输出信息：

  1. {
  2.   "args": {
  3.     "password": "secret",
  4.     "username": "wdbyte.com"
  5.   },
  6.   "headers": {
  7.     "Accept-Encoding": "gzip, x-gzip, deflate",
  8.     "Host": "httpbin.org",
  9.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)",
  10.     "X-Amzn-Trace-Id": "Root=1-62ecc660-69d58a226aefb1b6226541ec"
  11.   },
  12.   "origin": "42.120.75.185",
  13.   "url": "http://httpbin.org/get?username=wdbyte.com&password=secret"
  14. }

下面是通过抓包得到的请求响应信息格式：

  1. // 请求信息
  2. GET /get?username=wdbyte.com&password=secret HTTP/1.1
  3. Accept-Encoding: gzip, x-gzip, deflate
  4. Host: httpbin.org
  5. Connection: keep-alive
  6. User-Agent: Apache-HttpClient/5.1.3 (Java/1.8.0_151)
  8. // 响应信息
  9. HTTP/1.1 200 OK
  10. Date: Fri, 05 Aug 2022 07:27:30 GMT
  11. Content-Type: application/json
  12. Content-Length: 405
  13. Connection: keep-alive
  14. Server: gunicorn/19.9.0
  15. Access-Control-Allow-Origin: *
  16. Access-Control-Allow-Credentials: true
  18. {
  19.   "args": {
  20.     "password": "secret",
  21.     "username": "wdbyte.com"
  22.   },
  23.   "headers": {
  24.     "Accept-Encoding": "gzip, x-gzip, deflate",
  25.     "Host": "httpbin.org",
  26.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)",
  27.     "X-Amzn-Trace-Id": "Root=1-62ecc660-69d58a226aefb1b6226541ec"
  28.   },
  29.   "origin": "42.120.75.185",
  30.   "url": "http://httpbin.org/get?username=wdbyte.com&password=secret"
  31. }

HttpClient 5 POST 请求

下面演示发起一个 POST 请求，并携带表单参数。

参数：username=wdbyte.com&password=secret

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  4. import java.util.ArrayList;
  5. import java.util.List;
  7. import org.apache.hc.client5.http.classic.methods.HttpPost;
  8. import org.apache.hc.client5.http.entity.UrlEncodedFormEntity;
  9. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  10. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  11. import org.apache.hc.client5.http.impl.classic.HttpClients;
  12. import org.apache.hc.core5.http.HttpEntity;
  13. import org.apache.hc.core5.http.NameValuePair;
  14. import org.apache.hc.core5.http.ParseException;
  15. import org.apache.hc.core5.http.io.entity.EntityUtils;
  16. import org.apache.hc.core5.http.message.BasicNameValuePair;
  18. /**
  19. * @author https://www.wdbyte.com
  20.  */
  21. public class HttpClient5Post {
  23.     public static void main(String[] args) {
  24.         String result = post("http://httpbin.org/post");
  25.         System.out.println(result);
  26.     }
  27.     public static String post(String url) {
  28.         String result = null;
  29.         HttpPost httpPost = new HttpPost(url);
  30.         // 表单参数
  31.         List<NameValuePair> nvps = new ArrayList<>();
  32.         // POST 请求参数
  33.         nvps.add(new BasicNameValuePair("username", "wdbyte.com"));
  34.         nvps.add(new BasicNameValuePair("password", "secret"));
  35.         httpPost.setEntity(new UrlEncodedFormEntity(nvps));
  36.         try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
  37.             try (CloseableHttpResponse response = httpclient.execute(httpPost)) {
  38.                 System.out.println(response.getVersion()); // HTTP/1.1
  39.                 System.out.println(response.getCode()); // 200
  40.                 System.out.println(response.getReasonPhrase()); // OK
  42.                 HttpEntity entity = response.getEntity();
  43.                 // 获取响应信息
  44.                 result = EntityUtils.toString(entity);
  45.                 // 确保流被完全消费
  46.                 EntityUtils.consume(entity);
  47.             }
  48.         } catch (IOException | ParseException e) {
  49.             e.printStackTrace();
  50.         }
  51.         return result;
  52.     }
  54. }

输出信息：

  1. HTTP/1.1
  2. 200
  3. OK
  4. {
  5.   "args": {},
  6.   "data": "",
  7.   "files": {},
  8.   "form": {
  9.     "password": "secret",
  10.     "username": "wdbyte.com"
  11.   },
  12.   "headers": {
  13.     "Accept-Encoding": "gzip, x-gzip, deflate",
  14.     "Content-Length": "35",
  15.     "Content-Type": "application/x-www-form-urlencoded; charset=ISO-8859-1",
  16.     "Host": "httpbin.org",
  17.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/17)",
  18.     "X-Amzn-Trace-Id": "Root=1-62bb1ac8-489b2100728c81d70797a482"
  19.   },
  20.   "json": null,
  21.   "origin": "183.128.136.89",
  22.   "url": "http://httpbin.org/post"
  23. }

下面是通过 Wireshark 抓包得到的请求信息：

  1. POST /post HTTP/1.1
  2. Accept-Encoding: gzip, x-gzip, deflate
  3. Content-Length: 35
  4. Content-Type: application/x-www-form-urlencoded; charset=ISO-8859-1
  5. Host: httpbin.org
  6. Connection: keep-alive
  7. User-Agent: Apache-HttpClient/5.1.3 (Java/17)
  9. username=wdbyte.com&password=secret

HttpClient 5 Fluent POST

使用 Apache HttpClient 5 提供的 Fluent API 可以更便捷的发起 POST 请求，但是可操作的地方较少。

一样发送一个简单的表单参数：username=wdbyte.com&password=secret

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  5. import org.apache.hc.client5.http.fluent.Request;
  6. import org.apache.hc.core5.http.message.BasicNameValuePair;
  8. /**
  9. * @author https://www.wdbyte.com
  10.  */
  11. public class HttpClient5PostFluent {
  13.     public static void main(String[] args) {
  14.         String result = post("http://httpbin.org/post");
  15.         System.out.println(result);
  16.     }
  18.     public static String post(String url) {
  19.         String result = null;
  20.         Request request = Request.post(url);
  21.         // POST 请求参数
  22.         request.bodyForm(
  23.             new BasicNameValuePair("username", "wdbyte.com"),
  24.             new BasicNameValuePair("password", "secret"));
  25.         try {
  26.             result = request.execute().returnContent().asString();
  27.         } catch (IOException e) {
  28.             e.printStackTrace();
  29.         }
  30.         return result;
  31.     }
  32. }

输出信息：

  1. {
  2.   "args": {},
  3.   "data": "",
  4.   "files": {},
  5.   "form": {
  6.     "password": "secret",
  7.     "username": "wdbyte.com"
  8.   },
  9.   "headers": {
  10.     "Accept-Encoding": "gzip, x-gzip, deflate",
  11.     "Content-Length": "35",
  12.     "Content-Type": "application/x-www-form-urlencoded; charset=ISO-8859-1",
  13.     "Host": "httpbin.org",
  14.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/17)",
  15.     "X-Amzn-Trace-Id": "Root=1-62bb1c8a-7aee8c004f06919f31a2b533"
  16.   },
  17.   "json": null,
  18.   "origin": "183.128.136.89",
  19.   "url": "http://httpbin.org/post"
  20. }

HttpClient5 POST JSON 参数

使用 StringEntity 类存入 JSON 参数。

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  5. import org.apache.hc.client5.http.classic.methods.HttpPost;
  6. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  7. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  8. import org.apache.hc.client5.http.impl.classic.HttpClients;
  9. import org.apache.hc.core5.http.ParseException;
  10. import org.apache.hc.core5.http.io.entity.EntityUtils;
  11. import org.apache.hc.core5.http.io.entity.StringEntity;
  13. /**
  14. * @author https://www.wdbyte.com
  15.  */
  16. public class HttpClient5PostWithJson {
  18.     public static void main(String[] args) {
  19.         String json = "{"
  20.             + "    \"password\": \"secret\","
  21.             + "    \"username\": \"wdbyte.com\""
  22.             + "}";
  23.         String result = post("http://httpbin.org/post", json);
  24.         System.out.println(result);
  25.     }
  27.     public static String post(String url, String jsonBody) {
  28.         String result = null;
  29.         HttpPost httpPost = new HttpPost(url);
  30.         httpPost.setEntity(new StringEntity(jsonBody, ContentType.APPLICATION_JSON));
  32.         try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
  33.             try (CloseableHttpResponse response = httpclient.execute(httpPost)) {
  34.                 // 获取响应信息
  35.                 result = EntityUtils.toString(response.getEntity());
  36.             }
  37.         } catch (IOException | ParseException e) {
  38.             e.printStackTrace();
  39.         }
  40.         return result;
  41.     }
  43. }

输出信息：

  1. {
  2.   "args": {},
  3.   "data": "{    \"password\": \"secret\",    \"username\": \"wdbyte.com\"}",
  4.   "files": {},
  5.   "form": {},
  6.   "headers": {
  7.     "Accept-Encoding": "gzip, x-gzip, deflate",
  8.     "Content-Length": "55",
  9.     "Content-Type": "text/plain; charset=ISO-8859-1",
  10.     "Host": "httpbin.org",
  11.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/17)",
  12.     "X-Amzn-Trace-Id": "Root=1-62bb1dbb-5a963c1d798b06be3ee1a15e"
  13.   },
  14.   "json": {
  15.     "password": "secret",
  16.     "username": "wdbyte.com"
  17.   },
  18.   "origin": "183.128.136.89",
  19.   "url": "http://httpbin.org/post"
  20. }

下面是通过 Wireshark 抓包得到的请求响应信息：

  1. // 请求信息
  2. POST /post HTTP/1.1
  3. Accept-Encoding: gzip, x-gzip, deflate
  4. Content-Length: 55
  5. Content-Type: application/json; charset=UTF-8
  6. Host: httpbin.org
  7. Connection: keep-alive
  8. User-Agent: Apache-HttpClient/5.1.3 (Java/17)
  10. {    "password": "secret",    "username": "wdbyte.com"}
  12. // 响应信息
  13. HTTP/1.1 200 OK
  14. Date: Tue, 28 Jun 2022 15:30:17 GMT
  15. Content-Type: application/json
  16. Content-Length: 573
  17. Connection: keep-alive
  18. Server: gunicorn/19.9.0
  19. Access-Control-Allow-Origin: *
  20. Access-Control-Allow-Credentials: true
  22. {
  23.   "args": {},
  24.   "data": "{    \"password\": \"secret\",    \"username\": \"wdbyte.com\"}",
  25.   "files": {},
  26.   "form": {},
  27.   "headers": {
  28.     "Accept-Encoding": "gzip, x-gzip, deflate",
  29.     "Content-Length": "55",
  30.     "Content-Type": "application/json; charset=UTF-8",
  31.     "Host": "httpbin.org",
  32.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/17)",
  33.     "X-Amzn-Trace-Id": "Root=1-62bb1e89-64db55730a0361c720232ccd"
  34.   },
  35.   "json": {
  36.     "password": "secret",
  37.     "username": "wdbyte.com"
  38.   },
  39.   "origin": "183.128.136.89",
  40.   "url": "http://httpbin.org/post"
  41. }

HttpClient 5 设置超时

使用 RequestConfig 对象来配置超时时间。

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  5. import org.apache.hc.client5.http.classic.methods.HttpGet;
  6. import org.apache.hc.client5.http.config.RequestConfig;
  7. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  8. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  9. import org.apache.hc.client5.http.impl.classic.HttpClients;
  10. import org.apache.hc.core5.http.HttpEntity;
  11. import org.apache.hc.core5.http.ParseException;
  12. import org.apache.hc.core5.http.io.entity.EntityUtils;
  13. import org.apache.hc.core5.util.Timeout;
  15. /**
  16. * @author https://www.wdbyte.com
  17.  */
  18. public class HttpClient5GetWithTimeout {
  20.     public static void main(String[] args) {
  21.         String result = get("http://httpbin.org/get");
  22.         System.out.println(result);
  23.     }
  25.     public static String get(String url) {
  26.         String resultContent = null;
  27.         // 设置超时时间
  28.         RequestConfig config = RequestConfig.custom()
  29.             .setConnectTimeout(Timeout.ofMilliseconds(5000L))
  30.             .setConnectionRequestTimeout(Timeout.ofMilliseconds(5000L))
  31.             .setResponseTimeout(Timeout.ofMilliseconds(5000L))
  32.             .build();
  33.         // 请求级别的超时
  34.         HttpGet httpGet = new HttpGet(url);
  35.         //httpGet.setConfig(config);
  36.         //try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
  37.         // 客户端级别的超时
  38.         try (CloseableHttpClient httpclient = HttpClients.custom().setDefaultRequestConfig(config).build()) {
  39.             try (CloseableHttpResponse response = httpclient.execute(httpGet)) {
  40.                 // 获取状态码
  41.                 System.out.println(response.getVersion()); // HTTP/1.1
  42.                 System.out.println(response.getCode()); // 200
  43.                 System.out.println(response.getReasonPhrase()); // OK
  44.                 HttpEntity entity = response.getEntity();
  45.                 // 获取响应信息
  46.                 resultContent = EntityUtils.toString(entity);
  47.             }
  48.         } catch (IOException | ParseException e) {
  49.             e.printStackTrace();
  50.         }
  51.         return resultContent;
  52.     }
  54. }

HttpClient 5 异步请求

下面演示三种 HttpClient 5 异步请求方式。

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  4. import java.nio.CharBuffer;
  5. import java.util.concurrent.CountDownLatch;
  6. import java.util.concurrent.ExecutionException;
  7. import java.util.concurrent.Future;
  9. import org.apache.hc.client5.http.async.methods.AbstractCharResponseConsumer;
  10. import org.apache.hc.client5.http.async.methods.SimpleHttpRequest;
  11. import org.apache.hc.client5.http.async.methods.SimpleHttpRequests;
  12. import org.apache.hc.client5.http.async.methods.SimpleHttpResponse;
  13. import org.apache.hc.client5.http.impl.async.CloseableHttpAsyncClient;
  14. import org.apache.hc.client5.http.impl.async.HttpAsyncClients;
  15. import org.apache.hc.core5.concurrent.FutureCallback;
  16. import org.apache.hc.core5.http.ContentType;
  17. import org.apache.hc.core5.http.HttpException;
  18. import org.apache.hc.core5.http.HttpResponse;
  19. import org.apache.hc.core5.http.nio.AsyncRequestProducer;
  20. import org.apache.hc.core5.http.nio.support.AsyncRequestBuilder;
  22. /**
  23.  * HttpClient 5 异步请求
  24. * @author https://www.wdbyte.com
  25.  * @date 2022/06/25
  26.  */
  27. public class HttpClient5Async {
  29.     public static void main(String[] args) {
  30.         getAsync1("http://httpbin.org/get");
  31.         getAsync2("http://httpbin.org/get");
  32.         getAsync3("http://httpbin.org/get");
  33.     }
  35.     /**
  36.      * 异步请求
  37.      *
  38.      * @param url
  39.      * @return
  40.      */
  41.     public static String getAsync1(String url) {
  42.         try (CloseableHttpAsyncClient httpclient = HttpAsyncClients.createDefault()) {
  43.             // 开始 http clinet
  44.             httpclient.start();
  45.             // 执行请求
  46.             SimpleHttpRequest request1 = SimpleHttpRequests.get(url);
  47.             Future<SimpleHttpResponse> future = httpclient.execute(request1, null);
  48.             // 等待直到返回完毕
  49.             SimpleHttpResponse response1 = future.get();
  50.             System.out.println("getAsync1:" + request1.getRequestUri() + "->" + response1.getCode());
  51.         } catch (IOException | ExecutionException | InterruptedException e) {
  52.             throw new RuntimeException(e);
  53.         }
  54.         return null;
  55.     }
  57.     /**
  58.      * 异步请求，根据响应情况回调
  59.      *
  60.      * @param url
  61.      * @return
  62.      */
  63.     public static String getAsync2(String url) {
  64.         try (CloseableHttpAsyncClient httpclient = HttpAsyncClients.createDefault()) {
  65.             // 开始 http clinet
  66.             httpclient.start();
  67.             // 根据请求响应情况进行回调操作
  68.             CountDownLatch latch = new CountDownLatch(1);
  69.             SimpleHttpRequest request = SimpleHttpRequests.get(url);
  70.             httpclient.execute(request, new FutureCallback<SimpleHttpResponse>() {
  71.                 @Override
  72.                 public void completed(SimpleHttpResponse response2) {
  73.                     latch.countDown();
  74.                     System.out.println("getAsync2:" + request.getRequestUri() + "->" + response2.getCode());
  75.                 }
  77.                 @Override
  78.                 public void failed(Exception ex) {
  79.                     latch.countDown();
  80.                     System.out.println("getAsync2:" + request.getRequestUri() + "->" + ex);
  81.                 }
  83.                 @Override
  84.                 public void cancelled() {
  85.                     latch.countDown();
  86.                     System.out.println("getAsync2:" + request.getRequestUri() + " cancelled");
  87.                 }
  89.             });
  90.             latch.await();
  91.         } catch (IOException | InterruptedException e) {
  92.             throw new RuntimeException(e);
  93.         }
  94.         return null;
  95.     }
  97.     /**
  98.      * 异步请求，对响应流做点什么
  99.      *
  100.      * @param url
  101.      * @return
  102.      */
  103.     public static String getAsync3(String url) {
  104.         try (CloseableHttpAsyncClient httpclient = HttpAsyncClients.createDefault()) {
  105.             // 开始 http clinet
  106.             httpclient.start();
  107.             // 根据请求响应情况进行回调操作
  108.             SimpleHttpRequest request = SimpleHttpRequests.get(url);
  110.             CountDownLatch latch = new CountDownLatch(1);
  111.             AsyncRequestProducer producer = AsyncRequestBuilder.get("http://httpbin.org/get").build();
  112.             AbstractCharResponseConsumer<HttpResponse> consumer3 = new AbstractCharResponseConsumer<HttpResponse>() {
  114.                 HttpResponse response;
  116.                 @Override
  117.                 protected void start(HttpResponse response, ContentType contentType) throws HttpException, IOException {
  118.                     System.out.println("getAsync3: 开始响应....");
  119.                     this.response = response;
  120.                 }
  122.                 @Override
  123.                 protected int capacityIncrement() {
  124.                     return Integer.MAX_VALUE;
  125.                 }
  127.                 @Override
  128.                 protected void data(CharBuffer data, boolean endOfStream) throws IOException {
  129.                     System.out.println("getAsync3: 收到数据....");
  130.                     // Do something useful
  131.                 }
  133.                 @Override
  134.                 protected HttpResponse buildResult() throws IOException {
  135.                     System.out.println("getAsync3: 接收完毕...");
  136.                     return response;
  137.                 }
  139.                 @Override
  140.                 public void releaseResources() {
  141.                 }
  143.             };
  144.             httpclient.execute(producer, consumer3, new FutureCallback<HttpResponse>() {
  146.                 @Override
  147.                 public void completed(HttpResponse response) {
  148.                     latch.countDown();
  149.                     System.out.println("getAsync3: "+request.getRequestUri() + "->" + response.getCode());
  150.                 }
  152.                 @Override
  153.                 public void failed(Exception ex) {
  154.                     latch.countDown();
  155.                     System.out.println("getAsync3: "+request.getRequestUri() + "->" + ex);
  156.                 }
  158.                 @Override
  159.                 public void cancelled() {
  160.                     latch.countDown();
  161.                     System.out.println("getAsync3: "+request.getRequestUri() + " cancelled");
  162.                 }
  164.             });
  165.             latch.await();
  166.         } catch (IOException | InterruptedException e) {
  167.             throw new RuntimeException(e);
  168.         }
  169.         return null;
  171.     }
  172. }

输出结果：

  1. getAsync1:/get->200
  2. getAsync2:/get->200
  3. getAsync3: 开始响应....
  4. getAsync3: 收到数据....
  5. getAsync3: 收到数据....
  6. getAsync3: 收到数据....
  7. getAsync3: 接收完毕...
  8. getAsync3: /get->200

HttpClient 5 获取 Cookie

请求 http://httpbin.org/cookies/set/cookieName/www.wdbyte.com 的响应中会带有一个Cookie 信息，其中 name 为 cookieName，value 为 www.wdbyte.com，我们以此用作测试。

Postman 请求测试，可以看到响应了 Cookie 信息。

下面编写 Java 代码进行请求测试

  1. package com.wdbyte.httpclient;
  3. import java.util.List;
  5. import org.apache.hc.client5.http.classic.methods.HttpGet;
  6. import org.apache.hc.client5.http.cookie.BasicCookieStore;
  7. import org.apache.hc.client5.http.cookie.Cookie;
  8. import org.apache.hc.client5.http.cookie.CookieStore;
  9. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  10. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  11. import org.apache.hc.client5.http.impl.classic.HttpClients;
  12. import org.apache.hc.client5.http.impl.cookie.BasicClientCookie;
  13. import org.apache.hc.client5.http.protocol.HttpClientContext;
  14. import org.apache.hc.core5.http.io.entity.EntityUtils;
  16. /**
  17.  * 这个例子演示了使用本地HTTP上下文填充, 自定义属性
  18.  */
  19. public class HttpClient5WithCookie {
  21.     public static void main(final String[] args) throws Exception {
  22.         try (final CloseableHttpClient httpclient = HttpClients.createDefault()) {
  23.             // 创建一个本地的 Cookie 存储
  24.             final CookieStore cookieStore = new BasicCookieStore();
  25.             // BasicClientCookie clientCookie = new BasicClientCookie("name", "www.wdbyte.com");
  26.             // clientCookie.setDomain("http://httpbin.org/cookies");
  27.             // 过期时间
  28.             // clientCookie.setExpiryDate(new Date());
  29.             // 添加到本地 Cookie
  30.             // cookieStore.addCookie(clientCookie);
  32.             // 创建本地 HTTP 请求上下文 HttpClientContext
  33.             final HttpClientContext localContext = HttpClientContext.create();
  34.             // 绑定 cookieStore 到 localContext
  35.             localContext.setCookieStore(cookieStore);
  37.             final HttpGet httpget = new HttpGet("http://httpbin.org/cookies/set/cookieName/www.wdbyte.com");
  38.             System.out.println("执行请求 " + httpget.getMethod() + " " + httpget.getUri());
  40.             // 获取 Coolie 信息
  41.             try (final CloseableHttpResponse response = httpclient.execute(httpget, localContext)) {
  42.                 System.out.println("----------------------------------------");
  43.                 System.out.println(response.getCode() + " " + response.getReasonPhrase());
  44.                 final List<Cookie> cookies = cookieStore.getCookies();
  45.                 for (int i = 0; i < cookies.size(); i++) {
  46.                     System.out.println("Local cookie: " + cookies.get(i));
  47.                 }
  48.                 EntityUtils.consume(response.getEntity());
  49.             }
  50.         }
  51.     }
  53. }

输出结果：

  1. 执行请求 GET http://httpbin.org/cookies/set/cookieName/www.wdbyte.com
  2. ----------------------------------------
  3. 200 OK
  4. Local cookie: [name: cookieName; value: www.wdbyte.com; domain: httpbin.org; path: /; expiry: null]

HttpClient 5 读取文件内容请求

准备一个 JSON 内容格式的文件 params.json。

  1. {"name":"www.wdbyte.com"}

读取这个文件作为请求参数发起请求。

  1. package com.wdbyte.httpclient;
  3. import java.io.File;
  4. import java.io.FileInputStream;
  6. import org.apache.hc.client5.http.classic.methods.HttpPost;
  7. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  8. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  9. import org.apache.hc.client5.http.impl.classic.HttpClients;
  10. import org.apache.hc.core5.http.ContentType;
  11. import org.apache.hc.core5.http.io.entity.EntityUtils;
  12. import org.apache.hc.core5.http.io.entity.FileEntity;
  13. import org.apache.hc.core5.http.io.entity.InputStreamEntity;
  15. /**
  16.  * 加载数据流作为 POST 请求参数
  17.  */
  18. public class HttpClient5ChunkEncodedPost {
  20.     public static void main(final String[] args) throws Exception {
  21.         String params = "/Users/darcy/params.json";
  23.         try (final CloseableHttpClient httpclient = HttpClients.createDefault()) {
  24.             final HttpPost httppost = new HttpPost("http://httpbin.org/post");
  26.             final InputStreamEntity reqEntity = new InputStreamEntity(new FileInputStream(params), -1,
  27.                 ContentType.APPLICATION_JSON);
  28.             // 也可以使用 FileEntity 的形式
  29.             // FileEntity reqEntity = new FileEntity(new File(params), ContentType.APPLICATION_JSON);
  31.             httppost.setEntity(reqEntity);
  33.             System.out.println("执行请求 " + httppost.getMethod() + " " + httppost.getUri());
  34.             try (final CloseableHttpResponse response = httpclient.execute(httppost)) {
  35.                 System.out.println("----------------------------------------");
  36.                 System.out.println(response.getCode() + " " + response.getReasonPhrase());
  37.                 System.out.println(EntityUtils.toString(response.getEntity()));
  38.             }
  39.         }
  40.     }
  41. }

输出结果：

  1. 执行请求 POST http://httpbin.org/post
  2. ----------------------------------------
  3. 200 OK
  4. {
  5.   "args": {},
  6.   "data": "{\"name\":\"www.wdbyte.com\"}\n",
  7.   "files": {},
  8.   "form": {},
  9.   "headers": {
  10.     "Accept-Encoding": "gzip, x-gzip, deflate",
  11.     "Content-Length": "26",
  12.     "Content-Type": "application/json; charset=UTF-8",
  13.     "Host": "httpbin.org",
  14.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)",
  15.     "X-Amzn-Trace-Id": "Root=1-62ee4d95-1f956d4303cea09c52694c86"
  16.   },
  17.   "json": {
  18.     "name": "www.wdbyte.com"
  19.   },
  20.   "origin": "42.120.74.238",
  21.   "url": "http://httpbin.org/post"
  22. }

HttpClient 5 表单登录

表单登录可以理解为发起一个携带了认证信息的请求，然后得到响应的 Cookie 的过程。当然这里不仅仅适用于表单登录，也可以是简单的发起一个携带了表单信息的请求。

本应该使用 POST 请求发送表单参数测试，但是在 httpbin.org 中没有对应的接口用于测试，所以这里换成了 GET 请求

示例代码：

  1. package com.wdbyte.httpclient;
  3. import java.util.ArrayList;
  4. import java.util.List;
  6. import org.apache.hc.client5.http.classic.methods.HttpGet;
  7. import org.apache.hc.client5.http.cookie.BasicCookieStore;
  8. import org.apache.hc.client5.http.cookie.Cookie;
  9. import org.apache.hc.client5.http.entity.UrlEncodedFormEntity;
  10. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  11. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  12. import org.apache.hc.client5.http.impl.classic.HttpClients;
  13. import org.apache.hc.core5.http.HttpEntity;
  14. import org.apache.hc.core5.http.NameValuePair;
  15. import org.apache.hc.core5.http.io.entity.EntityUtils;
  16. import org.apache.hc.core5.http.message.BasicNameValuePair;
  18. /**
  19.  * 演示基于表单的登录
  20.  *
  21.  * @author https://www.wdbyte.com
  22.  */
  23. public class HttpClient5FormLogin {
  25.     public static void main(final String[] args) throws Exception {
  26.         final BasicCookieStore cookieStore = new BasicCookieStore();
  27.         try (final CloseableHttpClient httpclient = HttpClients.custom()
  28.                 .setDefaultCookieStore(cookieStore)
  29.                 .build()) {
  31.             // 本应该使用 POST 请求发送表单参数，但是在 httpbin.org 中没有对应的接口用于测试，所以这里换成了 GET 请求
  32.             // HttpPost httpPost = new HttpPost("http://httpbin.org/cookies/set/username/wdbyte.com");
  33.             HttpGet httpPost = new HttpGet("http://httpbin.org/cookies/set/username/wdbyte.com");
  34.             // POST 表单请求参数
  35.             List<NameValuePair> nvps = new ArrayList<>();
  36.             nvps.add(new BasicNameValuePair("username", "wdbyte.com"));
  37.             nvps.add(new BasicNameValuePair("password", "secret"));
  38.             httpPost.setEntity(new UrlEncodedFormEntity(nvps));
  40.             try (final CloseableHttpResponse response2 = httpclient.execute(httpPost)) {
  41.                 final HttpEntity entity = response2.getEntity();
  43.                 System.out.println("Login form get: " + response2.getCode() + " " + response2.getReasonPhrase());
  44.                 System.out.println("当前响应信息 "+EntityUtils.toString(entity));;
  46.                 System.out.println("Post 登录 Cookie:");
  47.                 final List<Cookie> cookies = cookieStore.getCookies();
  48.                 if (cookies.isEmpty()) {
  49.                     System.out.println("None");
  50.                 } else {
  51.                     for (int i = 0; i < cookies.size(); i++) {
  52.                         System.out.println("- " + cookies.get(i));
  53.                     }
  54.                 }
  55.             }
  56.         }
  57.     }
  58. }

输出结果：

  1. Login form get: 200 OK
  2. 当前响应信息 {
  3.   "cookies": {
  4.     "username": "wdbyte.com"
  5.   }
  6. }
  8. Post 登录 Cookie:
  9. - [name: username; value: wdbyte.com; domain: httpbin.org; path: /; expiry: null]

HttpClient 5 Basic Authorization

HTTP 基本认证（Basic Authorization）是一种比较简单的认证实现，主要流程如下

  1. 请求一个需要进行基本认证的 HTTP 接口，但是没有携带认证信息。
  2. 此时会响应 401 状态码，并在响应 header 中的 WWW-Authenticate 提示需要进行基本认证。
  3. 用户把需要提交认证信息进行冒号拼接，然后进行 base64 编码，再在得到的字符串开头拼接上 Basic 放入请求头 Authorization 中。
  4. 认证成功，响应成功。

你可以通过浏览器打开下面这个 URL 进行基本认证测试。

http://httpbin.org/basic-auth/admin/123456

在 Apache HttpClient 5 中的实现方式。

  1. package com.wdbyte.httpclient;
  3. import org.apache.hc.client5.http.auth.AuthScope;
  4. import org.apache.hc.client5.http.auth.UsernamePasswordCredentials;
  5. import org.apache.hc.client5.http.classic.methods.HttpGet;
  6. import org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider;
  7. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  8. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  9. import org.apache.hc.client5.http.impl.classic.HttpClients;
  10. import org.apache.hc.core5.http.io.entity.EntityUtils;
  12. /**
  13.  * 一个简单的示例,它使用HttpClient执行HTTP请求;
  14.  * 一个需要进行用户身份验证的目标站点。
  15.  */
  16. public class HttpClient5BasicAuthentication {
  18.     public static void main(final String[] args) throws Exception {
  19.         final BasicCredentialsProvider credsProvider = new BasicCredentialsProvider();
  20.         credsProvider.setCredentials(
  21.                 new AuthScope("httpbin.org", 80),
  22.                 new UsernamePasswordCredentials("admin", "123456".toCharArray()));
  23.         try (final CloseableHttpClient httpclient = HttpClients.custom()
  24.                 .setDefaultCredentialsProvider(credsProvider)
  25.                 .build()) {
  26.             final HttpGet httpget = new HttpGet("http://httpbin.org/basic-auth/admin/123456");
  28.             System.out.println("执行请求" + httpget.getMethod() + " " + httpget.getUri());
  29.             try (final CloseableHttpResponse response = httpclient.execute(httpget)) {
  30.                 System.out.println("----------------------------------------");
  31.                 System.out.println(response.getCode() + " " + response.getReasonPhrase());
  32.                 System.out.println(EntityUtils.toString(response.getEntity()));
  33.             }
  34.         }
  35.     }
  36. }

输出结果：

  1. 执行请求GET http://httpbin.org/basic-auth/user/passwd
  2. ----------------------------------------
  3. 200 OK
  4. {
  5.   "authenticated": true,
  6.   "user": "user"
  7. }

通过抓包可以看到完整的 HTTP 请求响应过程。

  1. // 请求
  2. GET /basic-auth/user/passwd HTTP/1.1
  3. Accept-Encoding: gzip, x-gzip, deflate
  4. Host: httpbin.org
  5. Connection: keep-alive
  6. User-Agent: Apache-HttpClient/5.1.3 (Java/1.8.0_151)
  7. // 响应
  8. HTTP/1.1 401 UNAUTHORIZED
  9. Date: Sat, 06 Aug 2022 08:25:33 GMT
  10. Content-Length: 0
  11. Connection: keep-alive
  12. Server: gunicorn/19.9.0
  13. WWW-Authenticate: Basic realm="Fake Realm"
  14. Access-Control-Allow-Origin: *
  15. Access-Control-Allow-Credentials: true
  16. // 请求
  17. GET /basic-auth/user/passwd HTTP/1.1
  18. Host: httpbin.org
  19. Connection: keep-alive
  20. User-Agent: Apache-HttpClient/5.1.3 (Java/1.8.0_151)
  21. Authorization: Basic dXNlcjpwYXNzd2Q=
  22. // 响应
  23. HTTP/1.1 200 OK
  24. Date: Sat, 06 Aug 2022 08:25:33 GMT
  25. Content-Type: application/json
  26. Content-Length: 47
  27. Connection: keep-alive
  28. Server: gunicorn/19.9.0
  29. Access-Control-Allow-Origin: *
  30. Access-Control-Allow-Credentials: true
  32. {
  33.   "authenticated": true,
  34.   "user": "user"
  35. }

HttpClient 5 Digest Authorization

HTTP Basic Authorization 的缺点显而易见，密码通过明文传输存在一定的安全风险，Digest Authorization 认证方式解决了明文传输的问题，这里不过多介绍 Digest 的相关内容，通过一个图简单的示意 Digest 认证方式的流程。

下面是代码演示。

  1. package com.wdbyte.httpclient;
  3. import org.apache.hc.client5.http.auth.AuthExchange;
  4. import org.apache.hc.client5.http.auth.AuthScheme;
  5. import org.apache.hc.client5.http.auth.AuthScope;
  6. import org.apache.hc.client5.http.auth.UsernamePasswordCredentials;
  7. import org.apache.hc.client5.http.classic.methods.HttpGet;
  8. import org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider;
  9. import org.apache.hc.client5.http.impl.auth.DigestScheme;
  10. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  11. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  12. import org.apache.hc.client5.http.impl.classic.HttpClients;
  13. import org.apache.hc.client5.http.protocol.HttpClientContext;
  14. import org.apache.hc.core5.http.HttpHost;
  15. import org.apache.hc.core5.http.io.entity.EntityUtils;
  17. /**
  18.  *
  19.  * HttpClient如何验证多个请求的示例
  20.  * 使用相同的摘要方案。在初始请求/响应交换之后
  21.  * 共享相同执行上下文的所有后续请求都可以重用
  22.  * 要向服务器进行身份验证的最后一个摘要nonce值。
  23.  */
  24. public class HttpClient5PreemptiveDigestAuthentication {
  26.     public static void main(final String[] args) throws Exception {
  27.         try (final CloseableHttpClient httpclient = HttpClients.createDefault()) {
  29.             final HttpHost target = new HttpHost("http", "httpbin.org", 80);
  31.             final HttpClientContext localContext = HttpClientContext.create();
  32.             final BasicCredentialsProvider credentialsProvider = new BasicCredentialsProvider();
  33.             credentialsProvider.setCredentials(
  34.                     new AuthScope(target),
  35.                     new UsernamePasswordCredentials("admin", "123456".toCharArray()));
  36.             localContext.setCredentialsProvider(credentialsProvider);
  38.             final HttpGet httpget = new HttpGet("http://httpbin.org/digest-auth/auth/admin/123456");
  40.             System.out.println("执行请求 " + httpget.getMethod() + " " + httpget.getUri());
  41.             for (int i = 0; i < 2; i++) {
  42.                 try (final CloseableHttpResponse response = httpclient.execute(target, httpget, localContext)) {
  43.                     System.out.println("----------------------------------------");
  44.                     System.out.println(response.getCode() + " " + response.getReasonPhrase());
  45.                     EntityUtils.consume(response.getEntity());
  47.                     final AuthExchange authExchange = localContext.getAuthExchange(target);
  48.                     if (authExchange != null) {
  49.                         final AuthScheme authScheme = authExchange.getAuthScheme();
  50.                         if (authScheme instanceof DigestScheme) {
  51.                             final DigestScheme digestScheme = (DigestScheme) authScheme;
  52.                             System.out.println("Nonce: " + digestScheme.getNonce() +
  53.                                     "; count: " + digestScheme.getNounceCount());
  54.                         }
  55.                     }
  56.                 }
  57.             }
  58.         }
  59.     }
  61. }

通过抓包工具可以清晰的看到 2 次请求的流程，在最后一次请求中，直接共享了认证信息，没有再次的重新认证的流程。

  1. // 1. 请求
  2. GET /digest-auth/auth/admin/123456 HTTP/1.1
  3. Accept-Encoding: gzip, x-gzip, deflate
  4. Host: httpbin.org
  5. Connection: keep-alive
  6. User-Agent: Apache-HttpClient/5.1.3 (Java/1.8.0_151)
  7. // 2. 详情，提示认证，给出参数
  8. HTTP/1.1 401 UNAUTHORIZED
  9. Date: Fri, 12 Aug 2022 07:11:06 GMT
  10. Content-Type: text/html; charset=utf-8
  11. Content-Length: 0
  12. Connection: keep-alive
  13. Server: gunicorn/19.9.0
  14. WWW-Authenticate: Digest realm="me@kennethreitz.com", nonce="8dc5e7974a86a6fcc3cf73230b0c4a93", qop="auth", opaque="64b7f68b386c3acc38131f7472aa2079", algorithm=MD5, stale=FALSE
  15. Set-Cookie: stale_after=never; Path=/
  16. Set-Cookie: fake=fake_value; Path=/
  17. Access-Control-Allow-Origin: *
  18. Access-Control-Allow-Credentials: true
  19. // 3. 参数+密码 加密后再次请求
  20. GET /digest-auth/auth/admin/123456 HTTP/1.1
  21. Host: httpbin.org
  22. Connection: keep-alive
  23. User-Agent: Apache-HttpClient/5.1.3 (Java/1.8.0_151)
  24. Cookie: fake=fake_value; stale_after=never
  25. Authorization: Digest username="admin", realm="me@kennethreitz.com", nonce="8dc5e7974a86a6fcc3cf73230b0c4a93", uri="/digest-auth/auth/admin/123456", response="7c6726f8ac54c1ba28e19c71b2fc7338", qop=auth, nc=00000001, cnonce="2fa61501d47a9d39", algorithm=MD5, opaque="64b7f68b386c3acc38131f7472aa2079"
  26. // 4. 认证成功，响应
  27. HTTP/1.1 200 OK
  28. Date: Fri, 12 Aug 2022 07:11:08 GMT
  29. Content-Type: application/json
  30. Content-Length: 48
  31. Connection: keep-alive
  32. Server: gunicorn/19.9.0
  33. Set-Cookie: fake=fake_value; Path=/
  34. Set-Cookie: stale_after=never; Path=/
  35. Access-Control-Allow-Origin: *
  36. Access-Control-Allow-Credentials: true
  38. {
  39.   "authenticated": true,
  40.   "user": "admin"
  41. }
  42. // 5. 再次请求，共享了登录状态。
  43. GET /digest-auth/auth/admin/123456 HTTP/1.1
  44. Accept-Encoding: gzip, x-gzip, deflate
  45. Host: httpbin.org
  46. Connection: keep-alive
  47. User-Agent: Apache-HttpClient/5.1.3 (Java/1.8.0_151)
  48. Cookie: fake=fake_value; stale_after=never
  49. Authorization: Digest username="admin", realm="me@kennethreitz.com", nonce="8dc5e7974a86a6fcc3cf73230b0c4a93", uri="/digest-auth/auth/admin/123456", response="9955ac79f6a51a876a326449447f549d", qop=auth, nc=00000002, cnonce="2fa61501d47a9d39", algorithm=MD5, opaque="64b7f68b386c3acc38131f7472aa2079"
  50. // 5. 认证成功，响应
  51. HTTP/1.1 200 OK
  52. Date: Fri, 12 Aug 2022 07:11:09 GMT
  53. Content-Type: application/json
  54. Content-Length: 48
  55. Connection: keep-alive
  56. Server: gunicorn/19.9.0
  57. Set-Cookie: fake=fake_value; Path=/
  58. Set-Cookie: stale_after=never; Path=/
  59. Access-Control-Allow-Origin: *
  60. Access-Control-Allow-Credentials: true
  62. {
  63.   "authenticated": true,
  64.   "user": "admin"
  65. }

HttpClient 5 拦截器

HttpClient 5 中的拦截器可以对请求过程的各个阶段进行拦截处理，通过 HttpClientBuilder 中的关于 Interceptor 的方法可以看到可以进行拦截的节点。

下面编写一个示例，发起三次请求，每次请求都在请求头 herader 中增加一个 request-id 参数，然后对 request-id 值为 2 的请求直接响应 404 结束。

  1. package com.wdbyte.httpclient;
  3. import java.io.IOException;
  4. import java.util.concurrent.atomic.AtomicLong;
  6. import org.apache.hc.client5.http.classic.ExecChain;
  7. import org.apache.hc.client5.http.classic.ExecChain.Scope;
  8. import org.apache.hc.client5.http.classic.ExecChainHandler;
  9. import org.apache.hc.client5.http.classic.methods.HttpGet;
  10. import org.apache.hc.client5.http.impl.ChainElement;
  11. import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
  12. import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
  13. import org.apache.hc.client5.http.impl.classic.HttpClients;
  14. import org.apache.hc.core5.http.ClassicHttpRequest;
  15. import org.apache.hc.core5.http.ClassicHttpResponse;
  16. import org.apache.hc.core5.http.ContentType;
  17. import org.apache.hc.core5.http.EntityDetails;
  18. import org.apache.hc.core5.http.Header;
  19. import org.apache.hc.core5.http.HttpEntity;
  20. import org.apache.hc.core5.http.HttpException;
  21. import org.apache.hc.core5.http.HttpRequest;
  22. import org.apache.hc.core5.http.HttpRequestInterceptor;
  23. import org.apache.hc.core5.http.HttpStatus;
  24. import org.apache.hc.core5.http.io.entity.EntityUtils;
  25. import org.apache.hc.core5.http.io.entity.StringEntity;
  26. import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
  27. import org.apache.hc.core5.http.protocol.HttpContext;
  29. /**
  30.  * 展示如何在请求和响应时进行拦截进行自定义处理。
  31.  */
  32. public class HttpClient5Interceptors {
  34.     public static void main(final String[] args) throws Exception {
  35.         try (final CloseableHttpClient httpclient = HttpClients.custom()
  36.             // 添加一个请求 id 到请求 header
  37.             .addRequestInterceptorFirst(new HttpRequestInterceptor() {
  38.                 private final AtomicLong count = new AtomicLong(0);
  39.                 @Override
  40.                 public void process(
  41.                     final HttpRequest request,
  42.                     final EntityDetails entity,
  43.                     final HttpContext context) throws HttpException, IOException {
  44.                     request.setHeader("request-id", Long.toString(count.incrementAndGet()));
  45.                 }
  46.             })
  47.             .addExecInterceptorAfter(ChainElement.PROTOCOL.name(), "custom", new ExecChainHandler() {
  48.                 // 请求 id 为 2 的，模拟 404 响应，并自定义响应的内容。
  49.                 @Override
  50.                 public ClassicHttpResponse execute(
  51.                     final ClassicHttpRequest request,
  52.                     final Scope scope,
  53.                     final ExecChain chain) throws IOException, HttpException {
  55.                     final Header idHeader = request.getFirstHeader("request-id");
  56.                     if (idHeader != null && "2".equalsIgnoreCase(idHeader.getValue())) {
  57.                         final ClassicHttpResponse response = new BasicClassicHttpResponse(HttpStatus.SC_NOT_FOUND,
  58.                             "Oppsie");
  59.                         response.setEntity(new StringEntity("bad luck", ContentType.TEXT_PLAIN));
  60.                         return response;
  61.                     } else {
  62.                         return chain.proceed(request, scope);
  63.                     }
  64.                 }
  65.             })
  66.             .build()) {
  68.             for (int i = 0; i < 3; i++) {
  69.                 final HttpGet httpget = new HttpGet("http://httpbin.org/get");
  71.                 try (final CloseableHttpResponse response = httpclient.execute(httpget)) {
  72.                     System.out.println("----------------------------------------");
  73.                     System.out.println("执行请求 " + httpget.getMethod() + " " + httpget.getUri());
  74.                     System.out.println(response.getCode() + " " + response.getReasonPhrase());
  75.                     System.out.println(EntityUtils.toString(response.getEntity()));
  76.                 }
  77.             }
  78.         }
  79.     }
  81. }

输出结果。

  1. ----------------------------------------
  2. 执行请求 GET http://httpbin.org/get
  3. 200 OK
  4. {
  5.   "args": {},
  6.   "headers": {
  7.     "Accept-Encoding": "gzip, x-gzip, deflate",
  8.     "Host": "httpbin.org",
  9.     "Request-Id": "1",
  10.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)",
  11.     "X-Amzn-Trace-Id": "Root=1-62f615ba-658ccd42182d22534dbba82c"
  12.   },
  13.   "origin": "42.120.75.221",
  14.   "url": "http://httpbin.org/get"
  15. }
  17. ----------------------------------------
  18. 执行请求 GET http://httpbin.org/get
  19. 404 Oppsie
  20. bad luck
  21. ----------------------------------------
  22. 执行请求 GET http://httpbin.org/get
  23. 200 OK
  24. {
  25.   "args": {},
  26.   "headers": {
  27.     "Accept-Encoding": "gzip, x-gzip, deflate",
  28.     "Host": "httpbin.org",
  29.     "Request-Id": "3",
  30.     "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)",
  31.     "X-Amzn-Trace-Id": "Root=1-62f615bb-4eb6ba10736ace0e21d0cb8c"
  32.   },
  33.   "origin": "42.120.75.221",
  34.   "url": "http://httpbin.org/get"
  35. }

一如既往，文章代码都存放在 Github.com/niumoo/javaNotes.

<完>

文章持续更新，可以微信搜一搜「 程序猿阿朗 」或访问「程序猿阿朗博客 」第一时间阅读。本文 Github.com/niumoo/JavaNotes 已经收录，有很多知识点和系列文章，欢迎Star。

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