4.5日学习打卡----学习Apache HttpClient 5

4.5日学习打卡

Apache Commons HttpClient

简介

Apache HttpClient 组件是为扩展而设计的，同时提供对基本HTTP协议的强大支持。

http://java.net包提供了通过HTTP访问资源的基本功能，但它并没有提供许多应用程序所需的全部灵活性或功能。HttpClient 组件通过提供一个高效、最新、功能丰富的包来填补这一空白，该包实现了最新HTTP标准的客户端。

HttpClient 过去是 Commons 的一部分，现在是 Apache HttpComponents 的一部分。Apache HttpComponents 是 Apache 的顶级项目，负责创建和维护专注于 HTTP 和相关协议的 Java 组件工具集。因此文章后面将不再使用 Commons HttpClient 字样，而是使用 HttpClient 。

HttpClient 目前有三个大版本，他们是不兼容的，可以同时存在。HttpClient 3过去是 Commons 的一部分，所以一般来说看到 Apache HttpClient 3的说法指的就是 Commons HttpClient，所属包 org.apache.commons.httpclient，maven 依赖如下

<!-- HttpClient 3 -->
<dependency>
    <groupId>commons-httpclient</groupId>
    <artifactId>commons-httpclient</artifactId>
    <version>3.1</version>
</dependency>

HttpClient 4 指的是 Apache HttpComponents 下的项目，所属包 org.apache.http，maven 依赖如下

<!-- HttpClient 4 -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>

HttpClient 5 指的是 Apache HttpComponents 下的最新项目，包结构是 org.apache.hc，依赖如下

<dependency>
    <groupId>org.apache.httpcomponents.client5</groupId>
    <artifactId>httpclient5</artifactId>
    <version>5.1</version>
</dependency>

HttpClient 3 早已不在维护，推荐使用最新的HttpClient 5。HttpClient 5 支持（经典API）（异步API）（反应式API）。

下面我将简单介绍下这几个版本 HttpClient 的用法。

1. 原生API
   我们先来看看如果不使用 HttpClient 而是使用 Java 原生 API，写一个 http 请求的例子

package com.jjy.httpclient5demo.test;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

public class JavaApi {
    public static void main(String[] args) {
        HttpsURLConnection conn = null;
        try {
            URL url = new URL("https://httpbin.org/get");
            conn = (HttpsURLConnection) url.openConnection();
            // https请求需要设置证书，为了简单此处默认信任服务器不做证书校验
            SSLContext sc = SSLContext.getInstance("SSL");
            sc.init(null, new TrustManager[]{new X509TrustManager() {
                @Override
                public void checkClientTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
                }
                @Override
                public void checkServerTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
                }
                @Override
                public X509Certificate[] getAcceptedIssuers() {
                    return new X509Certificate[0];
                }
            }}, new java.security.SecureRandom());

            conn.setSSLSocketFactory(sc.getSocketFactory());
            conn.setHostnameVerifier((s, sslSession) -> true);
            conn.setRequestMethod("GET");
            conn.setConnectTimeout(5000);
            conn.setReadTimeout(5000);
            conn.setUseCaches(false);
            conn.connect();
            InputStream is = conn.getInputStream();
            try (BufferedReader br = new BufferedReader(
                    new InputStreamReader(is))) {
                StringBuilder sb = new StringBuilder();
                String line;
                while ((line = br.readLine()) != null) {
                    sb.append(line).append("\n");
                }
                sb.deleteCharAt(sb.length() - 1);
                System.out.println(sb.toString());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }
    }
}

package com.jjy.httpclient5demo.test;

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpHeaders;
import java.io.IOException;
import java.nio.charset.StandardCharsets;

public class NativeJavaHttpClient {
    public static String get(String url) {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(url))
                .header("Accept", "application/json") // 如果需要的话，设置请求头
                .GET()
                .build();

        try {
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
            int statusCode = response.statusCode();
            System.out.println("Status Code: " + statusCode);
            System.out.println("Response Headers: " + response.headers());
            return response.body();
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
            return null;
        }
    }

    public static void main(String[] args) {
        String url = "http://httpbin.org/get";
        String responseContent = NativeJavaHttpClient.get(url);
        System.out.println(responseContent);
    }
}

我们看到这个例子是一个相对比较简单的 https 的 get请求，没有参数。代码已经比较复杂了，如果是 post 请求，需要传递参数，需要保存cookie（有些请求需求登录，我们还要先模拟登录请求后手动将 cookie 保存下来，下次请求在把 cookie 设置上）等场景代码将更为复杂。并且原生 API 默认不支持异步不支持响应式等，这时候就轮到 HttpClient 大显手身了。

2. HttpClient 3

package com.jjy.httpclient5demo.test;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.methods.GetMethod;

import java.io.IOException;

public class HttpClient3 {
    public static void main(String[] args) {
        // httpClient对象是线程安全的，可以单例使用，提升性能
        HttpClient httpClient = new HttpClient();
// 设置连接超时 和 socket超时
        httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(2000);
        httpClient.getHttpConnectionManager().getParams().setSoTimeout(5000); // 响应超时
        HttpMethod getM = new GetMethod("http://httpbin.org/get");
// 设置请求头
        getM.setRequestHeader("Content-Type", "application/json");
        NameValuePair p1 = new NameValuePair("name", "zs");
        NameValuePair p2 = new NameValuePair("age", "11");
// 设置查询参数，相当于 ?name=zs&age=11
        getM.setQueryString(new NameValuePair[]{p1, p2});
        try {
            int code = httpClient.executeMethod(getM);
            if (code == HttpStatus.SC_OK) {
                // 获取结果字符串
                String res = getM.getResponseBodyAsString();
                // InputStream res = getM.getResponseBodyAsStream(); // 也可以转换为流
                System.out.println(res);
            } else {
                System.err.println("请求失败，状态码：" + code);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 释放连接资源
            getM.releaseConnection();
        }
    }
}

3. HttpClient 4

import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.util.EntityUtils;
import org.apache.http.client.utils.URIBuilder;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

public class HttpClient4 {
    public static void main(String[] args) throws URISyntaxException {
        CloseableHttpClient httpClient = HttpClientBuilder.create().build();

        // 创建一个URIBuilder来构建带参数的URL  
        URIBuilder uriBuilder = new URIBuilder("http://httpbin.org/get");
        try {
            // 添加参数  
            uriBuilder.addParameter("name", "zs");
            uriBuilder.addParameter("age", "11");

            // 构建最终的URI  
            URI uri = uriBuilder.build();

            HttpGet httpGet = new HttpGet(uri);

            // 设置请求配置（超时等）  
            RequestConfig requestConfig = RequestConfig.custom()
                    .setConnectTimeout(2000) // 连接超时  
                    .setConnectionRequestTimeout(2000) // 请求超时  
                    .setSocketTimeout(2000) // 响应超时  
                    .build();
            httpGet.setConfig(requestConfig);

            // 设置请求头（如果需要）  
            // httpGet.setHeader("Content-Type", "application/json"); // 注意：GET请求通常不需要Content-Type头  

            try (CloseableHttpResponse response = httpClient.execute(httpGet)) {
                int statusCode = response.getStatusLine().getStatusCode();
                if (statusCode == HttpStatus.SC_OK) {
                    HttpEntity entity = response.getEntity();
                    System.out.println(EntityUtils.toString(entity, "UTF-8"));
                } else {
                    System.err.println("请求失败，状态码：" + statusCode);
                }
            } catch (IOException e) {
                System.err.println("请求异常：" + e.getMessage());
            }
        } catch (URISyntaxException e) {
            System.err.println("URI构建异常：" + e.getMessage());
        }
    }
}

Apache HttpClient 5

简介

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。
下面将会介绍 Apache HttpClient 5 中最为常见的一些用法：
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

依赖

maven

<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents.client5/httpclient5 -->
<dependency>
    <groupId>org.apache.httpcomponents.client5</groupId>
    <artifactId>httpclient5</artifactId>
    <version>5.1.3</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents.client5/httpclient5-fluent -->
<dependency>
    <groupId>org.apache.httpcomponents.client5</groupId>
    <artifactId>httpclient5-fluent</artifactId>
    <version>5.1.3</version>
</dependency>

HttpClient 5 GET 请求

package com.jjy.httpclient5demo.test;

import org.apache.hc.client5.http.classic.methods.HttpGet; // 导入Apache HttpClient 5的HttpGet类，用于发送HTTP GET请求  
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient; // 导入CloseableHttpClient类，表示一个可关闭的HTTP客户端  
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse; // 导入CloseableHttpResponse类，表示一个可关闭的HTTP响应  
import org.apache.hc.client5.http.impl.classic.HttpClients; // 导入HttpClients类，用于创建HttpClient实例  
import org.apache.hc.core5.http.HttpEntity; // 导入HttpEntity类，表示HTTP消息体  
import org.apache.hc.core5.http.ParseException; // 导入ParseException类，表示HTTP消息解析异常  
import org.apache.hc.core5.http.io.entity.EntityUtils; // 导入EntityUtils类，提供HTTP实体的工具方法  

// 注意：下面的导入似乎是不相关的，因为该类并不是一个Servlet  
// import javax.servlet.http.HttpServlet;  
// import javax.servlet.http.HttpServletRequest;  

import java.io.IOException; // 导入IO异常类  

public class GetHttp5Client {

    /**
     * 发送GET请求并返回响应内容  
     *
     * @param url 请求的URL  
     * @return 响应内容的字符串形式
     */
    public static String get(String url) {
        String resultContent = null; // 初始化响应内容的字符串为null  
        HttpGet httpGet = new HttpGet(url); // 创建HttpGet对象并设置请求的URL  
        try (CloseableHttpClient httpclient = HttpClients.createDefault()) { // 创建默认的CloseableHttpClient实例  
            try (CloseableHttpResponse response = httpclient.execute(httpGet)) { // 执行GET请求并获取响应  
                // 获取响应的状态信息  
                System.out.println(response.getVersion()); // 打印HTTP协议版本（例如：HTTP/1.1）  
                System.out.println(response.getCode()); // 打印响应的状态码（例如：200）  
                System.out.println(response.getReasonPhrase()); // 打印响应的状态描述（例如：OK）  
                HttpEntity entity = response.getEntity(); // 获取响应实体  
                // 将响应实体转换为字符串  
                resultContent = EntityUtils.toString(entity);
            }
        } catch (IOException | ParseException e) { // 捕获IO异常或HTTP消息解析异常  
            e.printStackTrace(); // 打印异常堆栈信息  
        }
        return resultContent; // 返回响应内容的字符串  
    }

    /**
     * 主函数，程序的入口点  
     *
     * @param args 命令行参数  
     */
    public static void main(String[] args) {
        // 测试GET请求，注意这里的URL已经被注释掉了，实际使用时可以取消注释并替换成需要的URL  
        // String url = "http://localhost:8080/user/loginwithcode";  
        // String url = "https://api.fastgpt.in/api/v1/chat/completions";  
        String url = "http://httpbin.org/get"; // 使用的测试URL  

        String s = GetHttp5Client.get(url); // 调用get方法发送GET请求并获取响应内容  
        System.out.println(s); // 打印响应内容  
    }
}

响应信息：

HTTP/1.1
200
OK
{
  "args": {}, 
  "headers": {
    "Accept-Encoding": "gzip, x-gzip, deflate", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/5.1.3 (Java/17)", 
    "X-Amzn-Trace-Id": "Root=1-62bb1891-5ab5e5376ed960471bf32f17"
  }, 
  "origin": "47.251.4.198", 
  "url": "http://httpbin.org/get"
}

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：

<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents.client5/httpclient5-fluent -->
<dependency>
    <groupId>org.apache.httpcomponents.client5</groupId>
    <artifactId>httpclient5-fluent</artifactId>
    <version>5.1.3</version>
</dependency>

示例:

package com.jjy.httpclient5demo;

import java.io.IOException;

import org.apache.hc.client5.http.fluent.Request; // 导入Apache HttpClient 5的fluent API的Request类，用于构建HTTP请求  
import org.apache.hc.client5.http.fluent.Response; // 导入Apache HttpClient 5的fluent API的Response类，用于处理HTTP响应  

/**
 * 使用Apache HttpClient 5的fluent API发送GET请求并获取响应内容  
 *
 * @author zbxmx
 */
public class HttpClient5GetFluent {

    /**
     * 主函数，程序的入口点  
     *
     * @param args 命令行参数  
     */
    public static void main(String[] args) {
        // 调用get方法发送GET请求，并打印返回的响应内容  
        System.out.println(get("http://httpbin.org/get"));
    }

    /**
     * 发送GET请求并返回响应内容  
     *
     * @param url 请求的URL  
     * @return 响应内容的字符串形式
     */
    public static String get(String url) {
        String result = null; // 初始化响应内容的字符串为null  
        try {
            // 使用fluent API构建GET请求并执行，获取响应对象  
            Response response = Request.get(url).execute();
            // 从响应对象中获取响应内容，并转换为字符串  
            result = response.returnContent().asString();
        } catch (IOException e) {
            // 捕获IO异常，并打印异常堆栈信息  
            e.printStackTrace();
        }
        // 返回响应内容的字符串  
        return result;
    }

}

HttpClient5 GET 请求参数

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

package com.jjy.httpclient5demo.test;


import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;

import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.NameValuePair;
import org.apache.hc.core5.http.ParseException;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.message.BasicNameValuePair;
import org.apache.hc.core5.net.URIBuilder;

/**
 * 使用Apache HttpClient 5的经典API发送带有参数的GET请求并获取响应内容
 *
 * @author zbxmx
 */
public class HttpClient5GetParams {

    /**
     * 主函数，程序的入口点
     *
     * @param args 命令行参数
     */
    public static void main(String[] args) {
        // 调用get方法发送带有参数的GET请求，并打印返回的响应内容
        String result = get("http://httpbin.org/get");
        System.out.println(result);
    }

    /**
     * 发送带有参数的GET请求并返回响应内容
     *
     * @param url 请求的URL
     * @return 响应内容的字符串形式
     */
    public static String get(String url) {
        String resultContent = null;

        // 创建HttpGet对象，设置请求的URL
        HttpGet httpGet = new HttpGet(url);

        // 创建存放表单参数的列表
        List<NameValuePair> nvps = new ArrayList<>();

        // 添加GET请求参数
        nvps.add(new BasicNameValuePair("username", "wdbyte.com"));
        nvps.add(new BasicNameValuePair("password", "secret"));

        // 使用URIBuilder构建新的URI，将参数添加到请求URL中
        try {
            URI uri = new URIBuilder(new URI(url))
                    .addParameters(nvps) // 将参数添加到URL中
                    .build(); // 构建完整的URI

            // 设置HttpGet对象的URI
            httpGet.setUri(uri);
        } catch (URISyntaxException e) {
            // 如果URI构建出错，则抛出运行时异常
            throw new RuntimeException(e);
        }

        try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
            // 创建默认的HttpClient实例
            try (CloseableHttpResponse response = httpclient.execute(httpGet)) {
                // 使用HttpClient执行GET请求，获取响应对象

                // 打印响应的HTTP版本、状态码和原因短语
                System.out.println(response.getVersion()); // HTTP/1.1
                System.out.println(response.getCode()); // 200
                System.out.println(response.getReasonPhrase()); // OK
                 
                HttpEntity entity = response.getEntity();

                // 将响应实体转换为字符串
                resultContent = EntityUtils.toString(entity);
            }
        } catch (IOException | ParseException e) {
            // 捕获IO异常或解析异常，并打印异常堆栈信息
            e.printStackTrace();
        }

        // 返回响应内容的字符串
        return resultContent;
    }
}

输出信息：

{
  "args": {
    "password": "secret", 
    "username": "wdbyte.com"
  }, 
  "headers": {
    "Accept-Encoding": "gzip, x-gzip, deflate", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)", 
    "X-Amzn-Trace-Id": "Root=1-62ecc660-69d58a226aefb1b6226541ec"
  }, 
  "origin": "218.26.154.94", 
  "url": "http://httpbin.org/get?username=wdbyte.com&password=secret"
}

HttpClient 5 POST 请求

下面演示发起一个 POST 请求，并携带表单参数。

package com.jjy.httpclient5demo.test;


import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;

import org.apache.hc.client5.http.classic.methods.HttpPost;
import org.apache.hc.client5.http.entity.UrlEncodedFormEntity;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.NameValuePair;
import org.apache.hc.core5.http.ParseException;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.message.BasicNameValuePair;
/**
 * 使用Apache HttpClient 5的经典API发送带有表单参数的POST请求并获取响应内容
 *
 * @author zbxmx
 */
public class HttpClient5Post {

    /**
     * 主函数，程序的入口点
     *
     * @param args 命令行参数
     */
    public static void main(String[] args) {
        // 调用post方法发送带有表单参数的POST请求，并打印返回的响应内容
        String result = post("http://httpbin.org/post");
        System.out.println(result);
    }

    /**
     * 发送带有表单参数的POST请求并返回响应内容
     *
     * @param url 请求的URL
     * @return 响应内容的字符串形式
     */
    public static String post(String url) {
        String result = null;

        // 创建HttpPost对象，设置请求的URL
        HttpPost httpPost = new HttpPost(url);

        // 创建存放表单参数的列表
        List<NameValuePair> nvps = new ArrayList<>();

        // 添加POST请求参数
        nvps.add(new BasicNameValuePair("username", "wdbyte.com"));
        nvps.add(new BasicNameValuePair("password", "secret"));

        // 创建UrlEncodedFormEntity，将表单参数添加到POST请求中
        httpPost.setEntity(new UrlEncodedFormEntity(nvps));


        try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
            // 创建默认的HttpClient实例
            try (CloseableHttpResponse response = httpclient.execute(httpPost)) {
                // 使用HttpClient执行POST请求，获取响应对象

                // 打印响应的HTTP版本、状态码和原因短语
                System.out.println(response.getVersion()); // HTTP/1.1
                System.out.println(response.getCode()); // 200
                System.out.println(response.getReasonPhrase()); // OK

                // 获取响应实体
                HttpEntity entity = response.getEntity();

                // 将响应实体转换为字符串
                result = EntityUtils.toString(entity);

                // 确保响应实体被完全消费，避免资源泄露
                EntityUtils.consume(entity);
            }
        } catch (IOException | ParseException e) {
            // 捕获IO异常，并打印异常堆栈信息
            e.printStackTrace();
        }

        // 返回响应内容的字符串
        return result;
    }
}

输出结果：

{
  "args": {}, 
  "data": "", 
  "files": {}, 
  "form": {
    "password": "secret", 
    "username": "wdbyte.com"
  }, 
  "headers": {
    "Accept-Encoding": "gzip, x-gzip, deflate", 
    "Content-Length": "35", 
    "Content-Type": "application/x-www-form-urlencoded; charset=ISO-8859-1", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/5.1.3 (Java/17.0.9)", 
    "X-Amzn-Trace-Id": "Root=1-660fe4f3-76d02ec05aa7a6535e833aad"
  }, 
  "json": null, 
  "origin": "218.26.154.94", 
  "url": "http://httpbin.org/post"
}

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。

package com.jjy.httpclient5demo.test;

import java.io.IOException;

import org.apache.hc.client5.http.fluent.Request;
import org.apache.hc.core5.http.message.BasicNameValuePair;

/**
 * @author zbzmx
 */
public class HttpClient5PostFluent {

    public static void main(String[] args) {
        String result = post("http://httpbin.org/post");
        System.out.println(result);
    }

    public static String post(String url) {
        String result = null;
        Request request = Request.post(url);
        // POST 请求参数
        request.bodyForm(
                new BasicNameValuePair("username", "wdbyte.com"),
                new BasicNameValuePair("password", "secret"));
        try {
            result = request.execute().returnContent().asString();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;
    }
}

HttpClient5 POST JSON 参数

package com.jjy.httpclient5demo.test;



import java.io.IOException;

import org.apache.hc.client5.http.classic.methods.HttpPost;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.ContentType;
import org.apache.hc.core5.http.ParseException;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.io.entity.StringEntity;

/**
 * @author zbxmx
 */
public class HttpClient5PostWithJson {

    public static void main(String[] args) {
        String json = "{"
                + "    \"password\": \"secret\","
                + "    \"username\": \"wdbyte.com\""
                + "}";
        String result = post("http://httpbin.org/post", json);
        System.out.println(result);
    }

    public static String post(String url, String jsonBody) {
        String result = null;
        HttpPost httpPost = new HttpPost(url);
        httpPost.setEntity(new StringEntity(jsonBody, ContentType.APPLICATION_JSON));

        try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
            try (CloseableHttpResponse response = httpclient.execute(httpPost)) {
                // 获取响应信息
                result = EntityUtils.toString(response.getEntity());
            }
        } catch (IOException | ParseException e) {
            e.printStackTrace();
        }
        return result;
    }

}

输出结果：

{
  "args": {}, 
  "data": "{    \"password\": \"secret\",    \"username\": \"wdbyte.com\"}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Accept-Encoding": "gzip, x-gzip, deflate", 
    "Content-Length": "55", 
    "Content-Type": "application/json; charset=UTF-8", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/5.1.3 (Java/17.0.9)", 
    "X-Amzn-Trace-Id": "Root=1-660ff565-0afd9ffd3d41ed4417652ca1"
  }, 
  "json": {
    "password": "secret", 
    "username": "wdbyte.com"
  }, 
  "origin": "218.26.154.94", 
  "url": "http://httpbin.org/post"
}

HttpClient 5 设置超时

使用 RequestConfig 对象来配置超时时间。

package com.jjy.httpclient5demo.test;


import java.io.IOException;

import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.config.RequestConfig;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.ParseException;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.util.Timeout;

/**
 * @author zbxmx
 */
public class HttpClient5GetWithTimeout {

    public static void main(String[] args) {
        String result = get("http://httpbin.org/get");
        System.out.println(result);
    }

    public static String get(String url) {
        String resultContent = null;
        // 设置超时时间
        RequestConfig config = RequestConfig.custom()
                .setConnectTimeout(Timeout.ofMilliseconds(5000L))
                .setConnectionRequestTimeout(Timeout.ofMilliseconds(5000L))
                .setResponseTimeout(Timeout.ofMilliseconds(5000L))
                .build();
        // 请求级别的超时
        HttpGet httpGet = new HttpGet(url);
        //httpGet.setConfig(config);
        //try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
        // 客户端级别的超时
        try (CloseableHttpClient httpclient = HttpClients.custom().setDefaultRequestConfig(config).build()) {
            try (CloseableHttpResponse response = httpclient.execute(httpGet)) {
                // 获取状态码
                System.out.println(response.getVersion()); // HTTP/1.1
                System.out.println(response.getCode()); // 200
                System.out.println(response.getReasonPhrase()); // OK
                HttpEntity entity = response.getEntity();
                // 获取响应信息
                resultContent = EntityUtils.toString(entity);
            }
        } catch (IOException | ParseException e) {
            e.printStackTrace();
        }
        return resultContent;
    }

}

HttpClient 5 异步请求

下面演示三种 HttpClient 5 异步请求方式。

package com.jjy.httpclient5demo.test;

import java.io.IOException;
import java.nio.CharBuffer;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

import org.apache.hc.client5.http.async.methods.AbstractCharResponseConsumer;
import org.apache.hc.client5.http.async.methods.SimpleHttpRequest;
import org.apache.hc.client5.http.async.methods.SimpleHttpRequests;
import org.apache.hc.client5.http.async.methods.SimpleHttpResponse;
import org.apache.hc.client5.http.impl.async.CloseableHttpAsyncClient;
import org.apache.hc.client5.http.impl.async.HttpAsyncClients;
import org.apache.hc.core5.concurrent.FutureCallback;
import org.apache.hc.core5.http.ContentType;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.HttpResponse;
import org.apache.hc.core5.http.nio.AsyncRequestProducer;
import org.apache.hc.core5.http.nio.support.AsyncRequestBuilder;

/**
 * HttpClient 5 异步请求
 * @author https://www.wdbyte.com
 *
 */
public class HttpClient5Async {

    public static void main(String[] args) {
        getAsync1("http://httpbin.org/get");
        getAsync2("http://httpbin.org/get");
        getAsync3("http://httpbin.org/get");
    }

    /**
     * 异步请求
     *
     * @param url
     * @return
     */
    public static String getAsync1(String url) {
        try (CloseableHttpAsyncClient httpclient = HttpAsyncClients.createDefault()) {
            // 开始 http clinet
            httpclient.start();
            // 执行请求
            SimpleHttpRequest request1 = SimpleHttpRequests.get(url);
            Future<SimpleHttpResponse> future = httpclient.execute(request1, null);
            // 等待直到返回完毕
            SimpleHttpResponse response1 = future.get();
            System.out.println("getAsync1:" + request1.getRequestUri() + "->" + response1.getCode());
        } catch (IOException | ExecutionException | InterruptedException e) {
            throw new RuntimeException(e);
        }
        return null;
    }

    /**
     * 异步请求，根据响应情况回调
     *
     * @param url
     * @return
     */
    public static String getAsync2(String url) {
        try (CloseableHttpAsyncClient httpclient = HttpAsyncClients.createDefault()) {
            // 开始 http clinet
            httpclient.start();
            // 根据请求响应情况进行回调操作
            CountDownLatch latch = new CountDownLatch(1);
            SimpleHttpRequest request = SimpleHttpRequests.get(url);
            httpclient.execute(request, new FutureCallback<SimpleHttpResponse>() {
                @Override
                public void completed(SimpleHttpResponse response2) {
                    latch.countDown();
                    System.out.println("getAsync2:" + request.getRequestUri() + "->" + response2.getCode());
                }

                @Override
                public void failed(Exception ex) {
                    latch.countDown();
                    System.out.println("getAsync2:" + request.getRequestUri() + "->" + ex);
                }

                @Override
                public void cancelled() {
                    latch.countDown();
                    System.out.println("getAsync2:" + request.getRequestUri() + " cancelled");
                }

            });
            latch.await();
        } catch (IOException | InterruptedException e) {
            throw new RuntimeException(e);
        }
        return null;
    }

    /**
     * 异步请求，对响应流做点什么
     *
     * @param url
     * @return
     */
    public static String getAsync3(String url) {
        try (CloseableHttpAsyncClient httpclient = HttpAsyncClients.createDefault()) {
            // 开始 http clinet
            httpclient.start();
            // 根据请求响应情况进行回调操作
            SimpleHttpRequest request = SimpleHttpRequests.get(url);

            CountDownLatch latch = new CountDownLatch(1);
            AsyncRequestProducer producer = AsyncRequestBuilder.get("http://httpbin.org/get").build();
            AbstractCharResponseConsumer<HttpResponse> consumer3 = new AbstractCharResponseConsumer<HttpResponse>() {

                HttpResponse response;

                @Override
                protected void start(HttpResponse response, ContentType contentType) throws HttpException, IOException {
                    System.out.println("getAsync3: 开始响应....");
                    this.response = response;
                }

                @Override
                protected int capacityIncrement() {
                    return Integer.MAX_VALUE;
                }

                @Override
                protected void data(CharBuffer data, boolean endOfStream) throws IOException {
                    System.out.println("getAsync3: 收到数据....");
                    // Do something useful
                }

                @Override
                protected HttpResponse buildResult() throws IOException {
                    System.out.println("getAsync3: 接收完毕...");
                    return response;
                }

                @Override
                public void releaseResources() {
                }

            };
            httpclient.execute(producer, consumer3, new FutureCallback<HttpResponse>() {

                @Override
                public void completed(HttpResponse response) {
                    latch.countDown();
                    System.out.println("getAsync3: "+request.getRequestUri() + "->" + response.getCode());
                }

                @Override
                public void failed(Exception ex) {
                    latch.countDown();
                    System.out.println("getAsync3: "+request.getRequestUri() + "->" + ex);
                }

                @Override
                public void cancelled() {
                    latch.countDown();
                    System.out.println("getAsync3: "+request.getRequestUri() + " cancelled");
                }

            });
            latch.await();
        } catch (IOException | InterruptedException e) {
            throw new RuntimeException(e);
        }
        return null;

    }
}

输出结果

getAsync1:/get->200
getAsync2:/get->200
getAsync3: 开始响应....
getAsync3: 收到数据....
getAsync3: 收到数据....
getAsync3: 收到数据....
getAsync3: 接收完毕...
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。

package com.jjy.httpclient5demo.test;

import java.util.List;

import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.cookie.BasicCookieStore;
import org.apache.hc.client5.http.cookie.Cookie;
import org.apache.hc.client5.http.cookie.CookieStore;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.client5.http.impl.cookie.BasicClientCookie;
import org.apache.hc.client5.http.protocol.HttpClientContext;
import org.apache.hc.core5.http.io.entity.EntityUtils;

/**
 * 这个例子演示了使用本地HTTP上下文填充, 自定义属性
 */
public class HttpClient5WithCookie {

    public static void main(final String[] args) throws Exception {
        try (final CloseableHttpClient httpclient = HttpClients.createDefault()) {
            // 创建一个本地的 Cookie 存储
            final CookieStore cookieStore = new BasicCookieStore();
            // BasicClientCookie clientCookie = new BasicClientCookie("name", "www.wdbyte.com");
            // clientCookie.setDomain("http://httpbin.org/cookies");
            // 过期时间
            // clientCookie.setExpiryDate(new Date());
            // 添加到本地 Cookie
            // cookieStore.addCookie(clientCookie);

            // 创建本地 HTTP 请求上下文 HttpClientContext
            final HttpClientContext localContext = HttpClientContext.create();
            // 绑定 cookieStore 到 localContext
            localContext.setCookieStore(cookieStore);

            final HttpGet httpget = new HttpGet("http://httpbin.org/cookies/set/cookieName/www.wdbyte.com");
            System.out.println("执行请求 " + httpget.getMethod() + " " + httpget.getUri());

            // 获取 Coolie 信息
            try (final CloseableHttpResponse response = httpclient.execute(httpget, localContext)) {
                System.out.println("----------------------------------------");
                System.out.println(response.getCode() + " " + response.getReasonPhrase());
                final List<Cookie> cookies = cookieStore.getCookies();
                for (int i = 0; i < cookies.size(); i++) {
                    System.out.println("Local cookie: " + cookies.get(i));
                }
                EntityUtils.consume(response.getEntity());
            }
        }
    }

}

输出结果：

执行请求 GET http://httpbin.org/cookies/set/cookieName/www.wdbyte.com
----------------------------------------
200 OK
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。

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

读取这个文件作为请求参数发起请求。

package com.jjy.httpclient5demo.test;


import java.io.File;
import java.io.FileInputStream;

import org.apache.hc.client5.http.classic.methods.HttpPost;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.ContentType;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.io.entity.FileEntity;
import org.apache.hc.core5.http.io.entity.InputStreamEntity;

/**
 * 加载数据流作为 POST 请求参数
 */
public class HttpClient5ChunkEncodedPost {

    public static void main(final String[] args) throws Exception {
        String params = "/Users/darcy/params.json";

        try (final CloseableHttpClient httpclient = HttpClients.createDefault()) {
            final HttpPost httppost = new HttpPost("http://httpbin.org/post");

            final InputStreamEntity reqEntity = new InputStreamEntity(new FileInputStream(params), -1,
                    ContentType.APPLICATION_JSON);
            // 也可以使用 FileEntity 的形式
            // FileEntity reqEntity = new FileEntity(new File(params), ContentType.APPLICATION_JSON);

            httppost.setEntity(reqEntity);

            System.out.println("执行请求 " + httppost.getMethod() + " " + httppost.getUri());
            try (final CloseableHttpResponse response = httpclient.execute(httppost)) {
                System.out.println("----------------------------------------");
                System.out.println(response.getCode() + " " + response.getReasonPhrase());
                System.out.println(EntityUtils.toString(response.getEntity()));
            }
        }
    }
}

输出结果

执行请求 POST http://httpbin.org/post
----------------------------------------
200 OK
{
  "args": {}, 
  "data": "{\"name\":\"www.wdbyte.com\"}\n", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Accept-Encoding": "gzip, x-gzip, deflate", 
    "Content-Length": "26", 
    "Content-Type": "application/json; charset=UTF-8", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)", 
    "X-Amzn-Trace-Id": "Root=1-62ee4d95-1f956d4303cea09c52694c86"
  }, 
  "json": {
    "name": "www.wdbyte.com"
  }, 
  "origin": "42.120.74.238", 
  "url": "http://httpbin.org/post"
}

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

package com.jjy.httpclient5demo.test;



import java.util.ArrayList;
import java.util.List;

import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.cookie.BasicCookieStore;
import org.apache.hc.client5.http.cookie.Cookie;
import org.apache.hc.client5.http.entity.UrlEncodedFormEntity;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.NameValuePair;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.message.BasicNameValuePair;

/**
 * 演示基于表单的登录
 *
 * @author zbxmx
 */
public class HttpClient5FormLogin {

    public static void main(final String[] args) throws Exception {
        final BasicCookieStore cookieStore = new BasicCookieStore();
        try (final CloseableHttpClient httpclient = HttpClients.custom()
                .setDefaultCookieStore(cookieStore)
                .build()) {

            // 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
            // HttpPost httpPost = new HttpPost("http://httpbin.org/cookies/set/username/wdbyte.com");
            HttpGet httpPost = new HttpGet("http://httpbin.org/cookies/set/username/wdbyte.com");
            // POST 表单请求参数
            List<NameValuePair> nvps = new ArrayList<>();
            nvps.add(new BasicNameValuePair("username", "wdbyte.com"));
            nvps.add(new BasicNameValuePair("password", "secret"));
            httpPost.setEntity(new UrlEncodedFormEntity(nvps));

            try (final CloseableHttpResponse response2 = httpclient.execute(httpPost)) {
                final HttpEntity entity = response2.getEntity();

                System.out.println("Login form get: " + response2.getCode() + " " + response2.getReasonPhrase());
                System.out.println("当前响应信息 "+EntityUtils.toString(entity));;

                System.out.println("Post 登录 Cookie:");
                final List<Cookie> cookies = cookieStore.getCookies();
                if (cookies.isEmpty()) {
                    System.out.println("None");
                } else {
                    for (int i = 0; i < cookies.size(); i++) {
                        System.out.println("- " + cookies.get(i));
                    }
                }
            }
        }
    }
}

输出结果：

Login form get: 200 OK
当前响应信息 {
  "cookies": {
    "username": "wdbyte.com"
  }
}
 
Post 登录 Cookie:
- [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

package com.jjy.httpclient5demo.test;


import org.apache.hc.client5.http.auth.AuthScope;
import org.apache.hc.client5.http.auth.UsernamePasswordCredentials;
import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.io.entity.EntityUtils;

/**
 * 一个简单的示例,它使用HttpClient执行HTTP请求;
 * 一个需要进行用户身份验证的目标站点。
 */
public class HttpClient5BasicAuthentication {

    public static void main(final String[] args) throws Exception {
        final BasicCredentialsProvider credsProvider = new BasicCredentialsProvider();
        credsProvider.setCredentials(
                new AuthScope("httpbin.org", 80),
                new UsernamePasswordCredentials("admin", "123456".toCharArray()));
        try (final CloseableHttpClient httpclient = HttpClients.custom()
                .setDefaultCredentialsProvider(credsProvider)
                .build()) {
            final HttpGet httpget = new HttpGet("http://httpbin.org/basic-auth/admin/123456");

            System.out.println("执行请求" + httpget.getMethod() + " " + httpget.getUri());
            try (final CloseableHttpResponse response = httpclient.execute(httpget)) {
                System.out.println("----------------------------------------");
                System.out.println(response.getCode() + " " + response.getReasonPhrase());
                System.out.println(EntityUtils.toString(response.getEntity()));
            }
        }
    }
}

输出结果

执行请求GET http://httpbin.org/basic-auth/user/passwd
----------------------------------------
200 OK
{
  "authenticated": true, 
  "user": "user"
}

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。

package com.jjy.httpclient5demo.test;


import org.apache.hc.client5.http.auth.AuthExchange;
import org.apache.hc.client5.http.auth.AuthScheme;
import org.apache.hc.client5.http.auth.AuthScope;
import org.apache.hc.client5.http.auth.UsernamePasswordCredentials;
import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider;
import org.apache.hc.client5.http.impl.auth.DigestScheme;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.client5.http.protocol.HttpClientContext;
import org.apache.hc.core5.http.HttpHost;
import org.apache.hc.core5.http.io.entity.EntityUtils;

/**
 *
 * HttpClient如何验证多个请求的示例
 * 使用相同的摘要方案。在初始请求/响应交换之后
 * 共享相同执行上下文的所有后续请求都可以重用
 * 要向服务器进行身份验证的最后一个摘要nonce值。
 */
public class HttpClient5PreemptiveDigestAuthentication {

    public static void main(final String[] args) throws Exception {
        try (final CloseableHttpClient httpclient = HttpClients.createDefault()) {

            final HttpHost target = new HttpHost("http", "httpbin.org", 80);

            final HttpClientContext localContext = HttpClientContext.create();
            final BasicCredentialsProvider credentialsProvider = new BasicCredentialsProvider();
            credentialsProvider.setCredentials(
                    new AuthScope(target),
                    new UsernamePasswordCredentials("admin", "123456".toCharArray()));
            localContext.setCredentialsProvider(credentialsProvider);

            final HttpGet httpget = new HttpGet("http://httpbin.org/digest-auth/auth/admin/123456");

            System.out.println("执行请求 " + httpget.getMethod() + " " + httpget.getUri());
            for (int i = 0; i < 2; i++) {
                try (final CloseableHttpResponse response = httpclient.execute(target, httpget, localContext)) {
                    System.out.println("----------------------------------------");
                    System.out.println(response.getCode() + " " + response.getReasonPhrase());
                    EntityUtils.consume(response.getEntity());

                    final AuthExchange authExchange = localContext.getAuthExchange(target);
                    if (authExchange != null) {
                        final AuthScheme authScheme = authExchange.getAuthScheme();
                        if (authScheme instanceof DigestScheme) {
                            final DigestScheme digestScheme = (DigestScheme) authScheme;
                            System.out.println("Nonce: " + digestScheme.getNonce() +
                                    "; count: " + digestScheme.getNounceCount());
                        }
                    }
                }
            }
        }
    }

}

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

HttpClient5 拦截器

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。

package com.jjy.httpclient5demo.test;


import java.io.IOException;
import java.util.concurrent.atomic.AtomicLong;

import org.apache.hc.client5.http.classic.ExecChain;
import org.apache.hc.client5.http.classic.ExecChain.Scope;
import org.apache.hc.client5.http.classic.ExecChainHandler;
import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.impl.ChainElement;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.ClassicHttpRequest;
import org.apache.hc.core5.http.ClassicHttpResponse;
import org.apache.hc.core5.http.ContentType;
import org.apache.hc.core5.http.EntityDetails;
import org.apache.hc.core5.http.Header;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.HttpRequest;
import org.apache.hc.core5.http.HttpRequestInterceptor;
import org.apache.hc.core5.http.HttpStatus;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.io.entity.StringEntity;
import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
import org.apache.hc.core5.http.protocol.HttpContext;

/**
 * 展示如何在请求和响应时进行拦截进行自定义处理。
 */
public class HttpClient5Interceptors {

    public static void main(final String[] args) throws Exception {
        try (final CloseableHttpClient httpclient = HttpClients.custom()
                // 添加一个请求 id 到请求 header
                .addRequestInterceptorFirst(new HttpRequestInterceptor() {
                    private final AtomicLong count = new AtomicLong(0);
                    @Override
                    public void process(
                            final HttpRequest request,
                            final EntityDetails entity,
                            final HttpContext context) throws HttpException, IOException {
                        request.setHeader("request-id", Long.toString(count.incrementAndGet()));
                    }
                })
                .addExecInterceptorAfter(ChainElement.PROTOCOL.name(), "custom", new ExecChainHandler() {
                    // 请求 id 为 2 的，模拟 404 响应，并自定义响应的内容。
                    @Override
                    public ClassicHttpResponse execute(
                            final ClassicHttpRequest request,
                            final Scope scope,
                            final ExecChain chain) throws IOException, HttpException {

                        final Header idHeader = request.getFirstHeader("request-id");
                        if (idHeader != null && "2".equalsIgnoreCase(idHeader.getValue())) {
                            final ClassicHttpResponse response = new BasicClassicHttpResponse(HttpStatus.SC_NOT_FOUND,
                                    "Oppsie");
                            response.setEntity(new StringEntity("bad luck", ContentType.TEXT_PLAIN));
                            return response;
                        } else {
                            return chain.proceed(request, scope);
                        }
                    }
                })
                .build()) {

            for (int i = 0; i < 3; i++) {
                final HttpGet httpget = new HttpGet("http://httpbin.org/get");

                try (final CloseableHttpResponse response = httpclient.execute(httpget)) {
                    System.out.println("----------------------------------------");
                    System.out.println("执行请求 " + httpget.getMethod() + " " + httpget.getUri());
                    System.out.println(response.getCode() + " " + response.getReasonPhrase());
                    System.out.println(EntityUtils.toString(response.getEntity()));
                }
            }
        }
    }

}

输出结果

----------------------------------------
执行请求 GET http://httpbin.org/get
200 OK
{
  "args": {}, 
  "headers": {
    "Accept-Encoding": "gzip, x-gzip, deflate", 
    "Host": "httpbin.org", 
    "Request-Id": "1", 
    "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)", 
    "X-Amzn-Trace-Id": "Root=1-62f615ba-658ccd42182d22534dbba82c"
  }, 
  "origin": "42.120.75.221", 
  "url": "http://httpbin.org/get"
}
 
----------------------------------------
执行请求 GET http://httpbin.org/get
404 Oppsie
bad luck
----------------------------------------
执行请求 GET http://httpbin.org/get
200 OK
{
  "args": {}, 
  "headers": {
    "Accept-Encoding": "gzip, x-gzip, deflate", 
    "Host": "httpbin.org", 
    "Request-Id": "3", 
    "User-Agent": "Apache-HttpClient/5.1.3 (Java/1.8.0_151)", 
    "X-Amzn-Trace-Id": "Root=1-62f615bb-4eb6ba10736ace0e21d0cb8c"
  }, 
  "origin": "42.120.75.221", 
  "url": "http://httpbin.org/get"
}

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