Apache HttpClient教程

Apache HttpClient - 代理验证

在本章中，我们将学习如何使用用户名和密码创建经过身份验证的HttpRequest，并使用示例将其通过代理隧道传送到目标主机.

步骤1 - 创建CredentialsProvider对象

CredentialsProvider接口维护一个集合以保存用户登录凭据.您可以通过实例化BasicCredentialsProvider类(此接口的默认实现)来创建其对象.

CredentialsProvider credentialsPovider = new BasicCredentialsProvider();

步骤2 - 设置凭据

您可以使用将所需凭据设置为CredentialsProvider对象setCredentials()方法.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.
凭据对象 : 指定凭据(用户名，密码).使用主机和代理的 setCredentials()方法设置凭据，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HttpClientBuilder对象

使用HttpClients 类的custom()方法创建 HttpClientBuilder，如下所示 :

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

步骤4 - 设置CredentialsProvider

您可以使用将CredentialsProvider对象设置为HttpClientBuilder对象setDefaultCredentialsProvider()方法.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

通过实例化创建目标和代理主机HttpHost 类.

//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

创建 RequestConfig.Builder 使用 custom()方法的对象.使用 setProxy()方法将以前创建的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.

创建 HttpGet 通过实例化HttpGet类来实现对象.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

通过传递HttpHost对象(目标)和请求(HttpGet)来执行请求)作为 execute()方法的参数.

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

示例

以下示例演示了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());

   } 
}