C#模拟http 发送post或get请求

private string HttpPost(string Url, string postDataStr)

         {              HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);              request.Method =  "POST" ;              request.ContentType =  "application/x-www-form-urlencoded" ;              request.ContentLength = Encoding.UTF8.GetByteCount(postDataStr);              request.CookieContainer = cookie;              Stream myRequestStream = request.GetRequestStream();              StreamWriter myStreamWriter =  new  StreamWriter(myRequestStream, Encoding.GetEncoding( "gb2312" ));              myStreamWriter.Write(postDataStr);              myStreamWriter.Close();                HttpWebResponse response = (HttpWebResponse)request.GetResponse();                response.Cookies = cookie.GetCookies(response.ResponseUri);              Stream myResponseStream = response.GetResponseStream();              StreamReader myStreamReader =  new  StreamReader(myResponseStream, Encoding.GetEncoding( "utf-8" ));              string  retString = myStreamReader.ReadToEnd();              myStreamReader.Close();              myResponseStream.Close();                return  retString;          }            public  string  HttpGet( string  Url,  string  postDataStr)          {              HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url + (postDataStr ==  ""  ?  ""  :  "?" ) + postDataStr);              request.Method =  "GET" ;              request.ContentType =  "text/html;charset=UTF-8" ;                HttpWebResponse response = (HttpWebResponse)request.GetResponse();              Stream myResponseStream = response.GetResponseStream();              StreamReader myStreamReader =  new  StreamReader(myResponseStream, Encoding.GetEncoding( "utf-8" ));              string  retString = myStreamReader.ReadToEnd();              myStreamReader.Close();              myResponseStream.Close();                return  retString;          }  

在post的时候有时也用的到cookie，像登录163发邮件时候就需要发送cookie，所以在外部一个cookie属性随时保存 CookieContainer cookie = new CookieContainer();

！注意：有时候请求会重定向，但我们就需要从重定向url获取东西，像QQ登录成功后获取sid，但上面的会自动根据重定向地址跳转。我们可以用:
request.AllowAutoRedirect = false;设置重定向禁用，你就可以从headers的Location属性中获取重定向地址