HttpWebRequest httpReq; 
HttpWebResponse httpResp; 

string strBuff = ""; 
char[] cbuffer = new char[256]; 
int byteRead = 0; 

string filename = @"c:\log.txt"; 
///定義寫入流操作 
public void WriteStream() 
{ 
Uri httpURL = new Uri(txtURL.Text);

///HttpWebRequest類繼承於WebRequest，並沒有自己的建構函式，需通過WebRequest的Creat方法 建立，並進行強制的型別轉換 
      httpReq = (HttpWebRequest)WebRequest.Create(httpURL); 
///通過HttpWebRequest的GetResponse()方法建立HttpWebResponse,強制型別轉換

   httpResp = (HttpWebResponse) httpReq.GetResponse(); 
///GetResponseStream()方法獲取HTTP響應的資料流,並嘗試取得URL中所指定的網頁內容

     ///若成功取得網頁的內容，則以System.IO.Stream形式返回，若失敗則產生ProtoclViolationException錯 誤。在此正確的做法應將以下的程式碼放到一個try塊中處理。這裡簡單處理 
Stream respStream = httpResp.GetResponseStream();

///返回的內容是Stream形式的，所以可以利用StreamReader類獲取GetResponseStream的內容，並以

StreamReader類的Read方法依次讀取網頁源程式程式碼每一行的內容，直至行尾（讀取的編碼格式：UTF8） 
StreamReader respStreamReader = new StreamReader(respStream,Encoding.UTF8);

byteRead = respStreamReader.Read(cbuffer,0,256); 

while (byteRead != 0) 
{ 
string strResp = new string(cbuffer,0,byteRead); 
                  strBuff = strBuff + strResp; 
                  byteRead = respStreamReader.Read(cbuffer,0,256); 
} 

respStream.Close(); 
txtHTML.Text = strBuff; 
}