问题描述：在使用request.GetResponse时，如果是400错误，将抛出异常信息，而获取不到返回内容，所以返回的内容只能在catch上面获取，转载于

http://blog.csdn.net/ahywg/article/details/26267113

解决方法：

 WebRequest request = WebRequest.Create("网址");

 Stream stream=null;

  try

  {

   using (WebResponse response = request.GetResponse())

   {

    	stream=response.GetResponseStream();

   }

  }  

  catch (WebException e)

  {   

	stream=e.Response.GetResponseStream();

}