httpwebrequest

string url = "http://b2b.hc360.com/rewrite-url/www/dl.html";

string indata = "LoginID=mytestcs&Passwd=aabbccdd";
string outdata="";

CookieContainer myCookieContainer=new CookieContainer();
//新建一个CookieContainer来存放Cookie集合
HttpWebRequest myHttpWebRequest=(HttpWebRequest)WebRequest.Create(url);
//新建一个HttpWebRequest
myHttpWebRequest.ContentType="application/x-www-form-urlencoded";
myHttpWebRequest.ContentLength=indata.Length;
myHttpWebRequest.Method="POST";
myHttpWebRequest.CookieContainer=myCookieContainer;
//设置HttpWebRequest的CookieContainer为刚才建立的那个myCookieContainer
Stream myRequestStream=myHttpWebRequest.GetRequestStream();
StreamWriter myStreamWriter=new StreamWriter(myRequestStream,Encoding.GetEncoding("gb2312"));
myStreamWriter.Write(indata);
//把数据写入HttpWebRequest的Request流
myStreamWriter.Close();
myRequestStream.Close();

//关闭打开对象
HttpWebResponse myHttpWebResponse=(HttpWebResponse)myHttpWebRequest.GetResponse();
//新建一个HttpWebResponse
myHttpWebResponse.Cookies=myCookieContainer.GetCookies(myHttpWebRequest.RequestUri);
//获取一个包含url的Cookie集合的CookieCollection
Stream myResponseStream=myHttpWebResponse.GetResponseStream();
StreamReader myStreamReader=new StreamReader(myResponseStream,Encoding.GetEncoding("gb2312"));
outdata=myStreamReader.ReadToEnd();
//把数据从HttpWebResponse的Response流中读出
myStreamReader.Close();
myResponseStream.Close();
Console.WriteLine(outdata);
//显示"登录"

//拿到了Cookie，再进行请求就能直接读取到登录后的内容了
myHttpWebRequest=(HttpWebRequest)WebRequest.Create(url);
myHttpWebRequest.CookieContainer=myCookieContainer;//*
//刚才那个CookieContainer已经存有了Cookie,把它附加到HttpWebRequest中则能直接通过验证
myHttpWebResponse=(HttpWebResponse)myHttpWebRequest.GetResponse();
myHttpWebResponse.Cookies=myCookieContainer.GetCookies(myHttpWebRequest.RequestUri);
myResponseStream=myHttpWebResponse.GetResponseStream();
myStreamReader=new StreamReader(myResponseStream,Encoding.GetEncoding("gb2312"));
outdata=myStreamReader.ReadToEnd();
myStreamReader.Close();
myResponseStream.Close();
Console.WriteLine(outdata);