使用HttpClient，您可以连接到需要用户名和密码的网站。本章介绍如何针对要求输入用户名和密码的站点执行客户端请求。

第1步 - 创建CredentialsProvider对象
CredentialsProvider接口维护一个集合以保存用户登录凭据。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();

第2步 - 设置凭据

可以使用setCredentials()方法将所需凭据设置为CredentialsProvider对象。

此方法接受以下给出的两个对象 -

• AuthScope对象 - 验证范围，指定主机名，端口号和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"));

第3步 - 创建HttpClientBuilder对象

使用HttpClients类的custom()方法创建HttpClientBuilder。

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

第4步 - 设置credentialsPovider
可以使用setDefaultCredentialsProvider()方法将上面创建的credentialsPovider对象设置为HttpClientBuilder。

将上一步中创建的CredentialProvider对象设置为客户端构建器，方法是将其传递给CredentialsProvider object()方法，如下所示。

clientbuilder = clientbuilder.setDefaultCredentialsProvider(credsProvider);

第5步 - 构建CloseableHttpClient

使用HttpClientBuilder类的build()方法构建CloseableHttpClient对象。

CloseableHttpClient httpclient = clientbuilder.build();

第6步 - 创建一个HttpGet对象并执行它
通过实例化HttpGet类来创建HttpRequest对象。使用execute()方法执行此请求。

//Creating a HttpGet object
HttpGet httpget = new HttpGet("http://www.zyiz.net/ ");

//Executing the Get request
HttpResponse httpresponse = httpclient.execute(httpget);

示例
以下是一个示例程序，演示了针对需要用户身份验证的目标站点执行HTTP请求。

import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.Credentials;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
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 UserAuthenticationExample {

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

      //Create an object of credentialsProvider
      CredentialsProvider credentialsPovider = new BasicCredentialsProvider();

      //Set the credentials
      AuthScope scope = new AuthScope("http://www.zyiz.net/", 80);

      Credentials credentials = new UsernamePasswordCredentials("USERNAME", "PASSWORD");
      credentialsPovider.setCredentials(scope,credentials);

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

      //Setting the credentials
      clientbuilder = clientbuilder.setDefaultCredentialsProvider(credentialsPovider);

      //Building the CloseableHttpClient object
      CloseableHttpClient httpclient = clientbuilder.build();

      //Creating a HttpGet object
      HttpGet httpget = new HttpGet("http://www.zyiz.net/index.php");

      //Printing the method used
      System.out.println(httpget.getMethod()); 

      //Executing the Get request
      HttpResponse httpresponse = httpclient.execute(httpget);

      //Printing the status line
      System.out.println(httpresponse.getStatusLine());
      int statusCode = httpresponse.getStatusLine().getStatusCode();
      System.out.println(statusCode);

      Header[] headers= httpresponse.getAllHeaders();
      for (int i = 0; i<headers.length;i++){
         System.out.println(headers[i].getName());
      }
   }
}

执行上面示例代码，得到以下结果：

GET
HTTP/1.1 200 OK
200