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  Apache HttpClient - 用户验证

  • 简述

    使用 HttpClient，您可以连接到需要用户名和密码的网站。 本章解释了如何对要求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 接口维护一个集合来保存用户登录凭据。 您可以通过实例化 BasicCredentialsProvider 类来创建它的对象，该类是该接口的默认实现。 
    
CredentialsProvider credentialsPovider = new BasicCredentialsProvider();

  • 第 2 步 - 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，如下所示 -
    • AuthScope 对象 - 指定主机名、端口号和身份验证方案名称等详细信息的身份验证范围。
    • 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 - 创建一个 HttpClientBuilder 对象

    使用 HttpClients 的 custom() 方法创建一个 HttpClientBuilder > 类。 
    
//Creating the HttpClientBuilder
HttpClientBuilder clientbuilder = HttpClients.custom();

  • 第 4 步 - 设置 credentialsPovider

    您可以使用 setDefaultCredentialsProvider() 方法将上述创建的 credentialsPovider 对象设置为 HttpClientBuilder。
    将上一步创建的 CredentialProvider 对象传递给 CredentialsProvider object() 方法，将其设置给客户端构建器，如下所示。 
    
clientbuilder = clientbuilder.setDefaultCredentialsProvider(credsProvider);

  • 第 5 步 - 构建 CloseableHttpClient

    使用 HttpClientBuilder 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 类来创建一个 HttpRequest 对象。 使用执行此请求 execute() 方法。 
    
//Creating a HttpGet object
HttpGet httpget = new HttpGet("https://www.jc2182.com/ ");
//Executing the Get request
HttpResponse httpresponse = httpclient.execute(httpget);

  • 示例

    以下是一个示例程序，它演示了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("https://www.jc2182.com/questions/", 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("https://www.jc2182.com/questions/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());
      }
   }
}

  • 输出

    执行时，上述程序生成以下输出。 
    
GET
HTTP/1.1 200 OK
200
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