使用HttpClient库,您可以发送请求或通过传递参数登录表单.
按照以下步骤登录表单.
HttpClients 类的 createDefault()方法返回一个对象类 CloseableHttpClient ,它是HttpClient接口的基本实现.使用此方法,创建一个HttpClient对象 :
CloseableHttpClient httpClient = HttpClients.createDefault();
使用类 RequestBuilder 来构建通过向其添加参数来请求.如果请求类型是PUT或POST,它会将参数作为URL编码实体添加到请求中
使用post()方法创建RequestBuilder对象(类型为POST).
//Building the post request object RequestBuilder reqbuilder = RequestBuilder.post();
使用RequestBuilder对象设置URI和参数RequestBuilder类的 setUri()和 addParameter()方法.
//Set URI and parameters RequestBuilder reqbuilder = reqbuilder.setUri("http://httpbin.org/post"); reqbuilder = reqbuilder1.addParameter("Name", "username").addParameter("password", "password");
设置所需参数后,构建 HttpUriRequest 使用 build()方法的对象.
//Building the HttpUriRequest object HttpUriRequest httppost = reqbuilder2.build();
CloseableHttpClient对象的execute方法接受HttpUriRequest(接口)对象(即HttpGet,HttpPost,HttpPut,HttpHead等)并返回一个响应对象.
执行前面步骤中创建的HttpUriRequest,将其传递给 execute()
方法.
//Execute the request HttpResponse httpresponse = httpclient.execute(httppost);
以下示例演示了如何通过发送登录凭据登录表单.在这里,我们发送了两个参数 : 用户名和密码到表单并尝试打印邮件实体和请求状态.
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()); } }
执行时,上述程序生成以下输出 :
{ "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
如果您的表单存储了cookie,而不是创建默认的 CloseableHttpClient 对象.
创建CookieStore对象通过instanti在BasicCookieStore类中.
//Creating a BasicCookieStore object BasicCookieStore cookieStore = new BasicCookieStore();
使用 HttpClients custom()方法创建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.
//Setting default cookie store to the client builder object Clientbuilder = clientbuilder.setDefaultCookieStore(cookieStore);
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,您传递的参数将被添加到cookie存储区.
您可以打印 CookieStore 对象的内容,在那里您可以看到参数(以及以前的页面存储的以前的参数).
要打印cookie,请使用从 CookieStore 对象获取所有Cookie getCookies()方法.此方法返回 List 对象.使用Iterator,打印列表对象内容,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()); }