原文地址：http://blog.csdn.net/qy20115549/article/details/52249232
目录
#模拟登陆的原因
很多网站，我们是无法直接获得服务器返回的数据，需要输入用户名及密码才能看到数据。如我们登陆人人网时，网站网址http://www.renren.com/。如图所示，看到的是一个登陆的界面，必须输入用户名及密码才能看到返回的数据。
登陆后，看到的数据，便可以通过爬虫将网站的html，或者json数据抓下来，解析。
#实战（demo）
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package renren.renren;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
public class RenRen {
/*以下是模拟登陆程序*/
/*输入你的用户名及密码，这里输入*/
private static String userName = "";
private static String password = "";
// Don't change the following URL
private static String renRenLoginURL = "http://www.renren.com/PLogin.do";
// The HttpClient is used in one session
private HttpResponse response;
private DefaultHttpClient httpclient = new DefaultHttpClient();
/*输入抓包的参数，即传递的参数*/
private boolean login() {
HttpPost httpost = new HttpPost(renRenLoginURL);
// All the parameters post to the web site
//建立一个NameValuePair数组，用于存储欲传送的参数，添加相关参数，见上图中的参数
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
nvps.add(new BasicNameValuePair("domain", "renren.com"));
nvps.add(new BasicNameValuePair("isplogin", "true"));
nvps.add(new BasicNameValuePair("submit", "登录"));
nvps.add(new BasicNameValuePair("email", userName));
nvps.add(new BasicNameValuePair("password", password));
try {
/*登陆成功，获取返回的数据，即html文件*/
httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8));
response = httpclient.execute(httpost);
} catch (Exception e) {
e.printStackTrace();
return false;
} finally {
httpost.abort();
}
return true;
}
private String getRedirectLocation() {
/*获取响应的头 url*/
Header locationHeader = response.getFirstHeader("Location");
if (locationHeader == null) {
return null;
}
return locationHeader.getValue();
}
/*获取html文本*/
private String getText(String redirectLocation) {
HttpGet httpget = new HttpGet(redirectLocation);
// Create a response handler
ResponseHandler<String> responseHandler = new BasicResponseHandler();
String responseBody = "";
try {
responseBody = httpclient.execute(httpget, responseHandler);
} catch (Exception e) {
e.printStackTrace();
responseBody = null;
} finally {
httpget.abort();
httpclient.getConnectionManager().shutdown();
}
return responseBody;
}
public void printText() {
/*如果注册成功了，输入相应后的html*/
if (login()) {
String redirectLocation = getRedirectLocation();
if (redirectLocation!= null) {
System.out.println(getText(redirectLocation));
}
}
}
/*main方法*/
public static void main(String[] args) {
RenRen renRen = new RenRen();
renRen.printText();
}
}
如下图所示，便获得了html文件，只要对这个html文件解析就行了。
有什么不明白的，请发邮件至1563178220@qq.com 合肥工业大学管理学院 钱洋
