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正在复制HTTP请求输入流

webrequest httpwebrequest asp.net-mvc asp.net c#

Adrian Grigore · 技术社区 · 16 年前

我正在实现一个代理操作方法,它将传入的Web请求转发到另一个网页,并添加一些标题。action方法对get请求起作用,但我仍在努力转发传入的post请求。

问题是我不知道如何正确地将请求体写入传出的HTTP请求流。

以下是迄今为止我得到的简短版本:

//the incoming request stream
var requestStream=HttpContext.Current.Request.InputStream;
//the outgoing web request
var webRequest = (HttpWebRequest)WebRequest.Create(url);
...

//copy incoming request body to outgoing request
if (requestStream != null && requestStream.Length>0)
            {
                long length = requestStream.Length;
                webRequest.ContentLength = length;
                requestStream.CopyTo(webRequest.GetRequestStream())                    
            }

//THE NEXT LINE THROWS A ProtocolViolationException
 using (HttpWebResponse response = (HttpWebResponse)webRequest.GetResponse())
                {
                    ...
                }

一旦我对传出的HTTP请求调用GetResponse,就会得到以下异常:

ProtocolViolationException: You must write ContentLength bytes to the request stream before calling [Begin]GetResponse.

我不明白为什么会发生这种情况,因为requeststream.copyto应该负责编写正确数量的字节。

任何建议都将不胜感激。

谢谢,

阿德里安

3 回复 | 直到 14 年前

Brian 15 年前

是的,.net对此非常挑剔。解决这个问题的方法是两个都冲洗和关闭流。换言之:

Stream webStream = null;

try
{
    //copy incoming request body to outgoing request
    if (requestStream != null && requestStream.Length>0)
    {
        long length = requestStream.Length;
        webRequest.ContentLength = length;
        webStream = webRequest.GetRequestStream();
        requestStream.CopyTo(webStream);
    }
}
finally
{
    if (null != webStream)
    {
        webStream.Flush();
        webStream.Close();    // might need additional exception handling here
    }
}

// No more ProtocolViolationException!
using (HttpWebResponse response = (HttpWebResponse)webRequest.GetResponse())
{
    ...
}

Seth 14 年前

然而,答案@brian有效,我发现一旦调用了requeststream.copyto(stream),它就会触发我的httpwebresponse。这是个问题,因为我还没有准备好发送请求。因此,如果有人对发送的不是所有请求头或其他数据有问题,那是因为CopyTo正在触发您的请求。

ajay_whiz 16 年前

尝试修改if语句内的块

long length = requestStream.Length;
webRequest.ContentLength = length;
requestStream.CopyTo(webRequest.GetRequestStream())

具有

webRequest.Method = "POST";
webRequest.ContentLength = requestStream.Length;
webRequest.ContentType = "application/x-www-form-urlencoded";
Stream stream = webRequest.GetRequestStream();
requestStream.CopyTo(stream);
stream.Close();