📌  相关文章
📜  Apache HttpClient-基于表单的登录

📅  最后修改于: 2020-11-18 08:30:32             🧑  作者: Mango

使用HttpClient库，您可以发送请求或通过传递参数登录到表单。

请按照下面给出的步骤登录表单。

第1步-创建HttpClient对象

HttpClients类的createDefault()方法返回CloseableHttpClient类的对象，该对象是HttpClient接口的基本实现。使用此方法，创建HttpClient对象-

CloseableHttpClient httpClient = HttpClients.createDefault();

第2步-创建一个RequestBuilder对象

RequestBuilder类用于通过向其添加参数来构建请求。如果请求类型是PUT或POST，它将参数添加为URL编码实体的请求

使用post()方法创建一个RequestBuilder对象(POST类型)。

//Building the post request object
RequestBuilder reqbuilder = RequestBuilder.post();

步骤3-将Uri和参数设置为RequestBuilder。

使用RequestBuilder类的setUri()和addParameter()方法将URI和参数设置为RequestBuilder对象。

//Set URI and parameters
RequestBuilder reqbuilder = reqbuilder.setUri("http://httpbin.org/post");
reqbuilder = reqbuilder1.addParameter("Name", "username").addParameter("password", "password");

步骤4-构建HttpUriRequest对象

设置所需的参数后，使用build()方法构建HttpUriRequest对象。

//Building the HttpUriRequest object
HttpUriRequest httppost = reqbuilder2.build();

第5步-执行请求

CloseableHttpClient对象的execute方法接受HttpUriRequest(接口)对象(即HttpGet，HttpPost，HttpPut，HttpHead等)，并返回响应对象。

通过将其传递给execute()方法，执行在先前步骤中创建的HttpUriRequest。

//Execute the request
HttpResponse httpresponse = httpclient.execute(httppost);

例

下面的示例演示如何通过发送登录凭据登录到表单。在这里，我们向表单发送了两个参数-用户名和密码，并尝试打印消息实体和请求状态。

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.client.methods.RequestBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import java.io.IOException;
import java.net.URISyntaxException;

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

      //Creating CloseableHttpClient object
      CloseableHttpClient httpclient = HttpClients.createDefault();
 
      //Creating the RequestBuilder object
      RequestBuilder reqbuilder = RequestBuilder.post();

      //Setting URI and parameters
      RequestBuilder reqbuilder1 = reqbuilder.setUri("http://httpbin.org/post");
      RequestBuilder reqbuilder2 = reqbuilder1.addParameter("Name", 
         "username").addParameter("password", "password");

      //Building the HttpUriRequest object
      HttpUriRequest httppost = reqbuilder2.build();

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

      //Printing the status and the contents of the response
      System.out.println(EntityUtils.toString(httpresponse.getEntity()));
      System.out.println(httpresponse.getStatusLine());
   }
}

输出

在执行时，以上程序生成以下输出-

{
   "args": {},
   "data": "",
   "files": {},
   "form": {
      "Name": "username",
      "password": "password"
   },
   "headers": {
      "Accept-Encoding": "gzip,deflate",
      "Connection": "close",
      "Content-Length": "31",
      "Content-Type": "application/x-www-form-urlencoded; charset = UTF-8",
      "Host": "httpbin.org",
      "User-Agent": "Apache-HttpClient/4.5.6 (Java/1.8.0_91)"
   },
   "json": null,
   "origin": "117.216.245.180",
   "url": "http://httpbin.org/post"
}
HTTP/1.1 200 OK

带有Cookie的表单登录

如果您的表单存储cookie，而不是创建默认的CloseableHttpClient对象。

通过实例化BasicCookieStore类创建一个CookieStore对象。

//Creating a BasicCookieStore object
BasicCookieStore cookieStore = new BasicCookieStore();

使用HttpClients类的custom()方法创建一个HttpClientBuilder 。

//Creating an HttpClientBuilder object
HttpClientBuilder clientbuilder = HttpClients.custom();

使用setDefaultCookieStore()方法将cookie存储设置为客户端构建器。

//Setting default cookie store to the client builder object
Clientbuilder = clientbuilder.setDefaultCookieStore(cookieStore);

使用build()方法构建CloseableHttpClient对象。

//Building the CloseableHttpClient object
CloseableHttpClient httpclient = clientbuilder1.build();

通过传递执行请求来构建上面指定的HttpUriRequest对象。

如果页面存储cookie，则您传递的参数将添加到cookie存储。

您可以打印CookieStore对象的内容，在其中可以看到您的参数(以防万一，还有存储在页面中的先前参数)。

要打印cookie，请使用getCookies()方法从CookieStore对象获取所有cookie。此方法返回一个List对象。使用Iterator，打印列表对象的内容，如下所示-

//Printing the cookies
List list = cookieStore.getCookies();

System.out.println("list of cookies");
Iterator it = list.iterator();
if(it.hasNext()) {
   System.out.println(it.next());
}