Apache HttpClient - 代理身份验证

在本章中，我们将使用示例学习如何使用用户名和密码创建 Http 请求身份验证，并通过代理将其隧道传输到目标主机。

步骤 1 - 创建 CredentialsProvider 对象

CredentialsProvider 接口维护一个集合来保存用户登录凭据。 您可以通过实例化该接口的默认实现 BasicCredentialsProvider 类来创建其对象。

CredentialsProvider credentialsPovider = new BasicCredentialsProvider();

步骤 2 - 设置凭据

您可以使用 setCredentials() 方法为 CredentialsProvider 对象设置所需的凭据。 此方法接受两个对象 −

• AuthScope 对象 − 身份验证范围指定主机名、端口号和身份验证方案名称等详细信息。

• Credentials 对象 − 指定凭据（用户名、密码）。 使用 setCredentials() 方法为主机和代理设置凭据，如下所示。

credsProvider.setCredentials(new AuthScope("example.com", 80), new
   UsernamePasswordCredentials("user", "mypass"));
credsProvider.setCredentials(new AuthScope("localhost", 8000), new
   UsernamePasswordCredentials("abc", "passwd"));

步骤 3 - 创建一个 HttpClientBuilder 对象

使用HttpClients类的custom()方法创建一个HttpClientBuilder，如下图 −

//Creating the HttpClientBuilder
HttpClientBuilder clientbuilder = HttpClients.custom();

步骤 4 - 设置 CredentialsProvider

您可以使用 setDefaultCredentialsProvider() 方法将 CredentialsProvider 对象设置为 HttpClientBuilder 对象。 将先前创建的 CredentialsProvider 对象传递给此方法。

clientbuilder = clientbuilder.setDefaultCredentialsProvider(credsProvider);

步骤 5 - 构建 CloseableHttpClient

使用 build() 方法构建 CloseableHttpClient 对象。

CloseableHttpClient httpclient = clientbuilder.build();

步骤 6 - 创建代理和目标主机

通过实例化 HttpHost 类来创建目标和代理主机。

//Creating the target and proxy hosts
HttpHost target = new HttpHost("example.com", 80, "http");
HttpHost proxy = new HttpHost("localhost", 8000, "http");

步骤 7 - 设置代理并构建 RequestConfig 对象

使用 custom() 方法创建一个 RequestConfig.Builder 对象。使用 setProxy() 方法将先前创建的 proxyHost 对象设置为 RequestConfig.Builder。最后，使用 build() 方法构建 RequestConfig 对象。

RequestConfig.Builder reqconfigconbuilder= RequestConfig.custom();
reqconfigconbuilder = reqconfigconbuilder.setProxy(proxyHost);
RequestConfig config = reqconfigconbuilder.build();

步骤 8 - 创建一个 HttpGet 请求对象并为其设置配置对象。

通过实例化 HttpGet 类创建一个 HttpGet 对象。 使用 setConfig() 方法将上一步中创建的配置对象设置为此对象。

//Create the HttpGet request object
HttpGet httpGet = new HttpGet("/");

//Setting the config to the request
httpget.setConfig(config);

步骤 9 - 执行请求

通过将 HttpHost 对象（目标）和请求 (HttpGet) 作为参数传递给 execute() 方法来执行请求。

HttpResponse httpResponse = httpclient.execute(targetHost, httpget);

示例

以下示例演示如何使用用户名和密码通过代理执行 HTTP 请求。

import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;

public class ProxyAuthenticationExample {
   public static void main(String[] args) throws Exception {

      //Creating the CredentialsProvider object
      CredentialsProvider credsProvider = new BasicCredentialsProvider();

      //Setting the credentials
      credsProvider.setCredentials(new AuthScope("example.com", 80), 
         new UsernamePasswordCredentials("user", "mypass"));
      credsProvider.setCredentials(new AuthScope("localhost", 8000), 
         new UsernamePasswordCredentials("abc", "passwd"));

      //Creating the HttpClientBuilder
      HttpClientBuilder clientbuilder = HttpClients.custom();

      //Setting the credentials
      clientbuilder = clientbuilder.setDefaultCredentialsProvider(credsProvider);
      
      //Building the CloseableHttpClient object
      CloseableHttpClient httpclient = clientbuilder.build();

      //Create the target and proxy hosts
      HttpHost targetHost = new HttpHost("example.com", 80, "http");
      HttpHost proxyHost = new HttpHost("localhost", 8000, "http");

      //Setting the proxy
      RequestConfig.Builder reqconfigconbuilder= RequestConfig.custom();
      reqconfigconbuilder = reqconfigconbuilder.setProxy(proxyHost);
      RequestConfig config = reqconfigconbuilder.build();

      //Create the HttpGet request object
      HttpGet httpget = new HttpGet("/");

      //Setting the config to the request
      httpget.setConfig(config);
 
      //Printing the status line
      HttpResponse response = httpclient.execute(targetHost, httpget);
      System.out.println(response.getStatusLine());

   }
}

输出

执行时，上述程序生成以下输出 −

HTTP/1.1 200 OK