C#保存指定Url页面源码

private string gethtml(string url)
  {

   system.net.webclient client = new system.net.webclient();

   try
   {
    byte[] buf  = client.downloaddata(url);
   
    //message.text = system.text.encoding.getencoding("gb2312").getstring(buf);
    return system.text.encoding.getencoding("gb2312").getstring(buf);

   }
   catch( exception err)
   {
    message.text = err.message;
   }
   return null;
           
  }