How to drop body of a request after checking headers in Servlet

问题

I want to check the header of the request whether it contains a certain header or not before continuing with the body. For example, I want to check whether a multipart/form-data contains "Authorization" in the header or not. If it is not then there is no need to continue with uploading the multipart body which are generally quite large for file uploading.

Does servlet allow you to do this? I have tried to search on google randomly but there is no luck. Here is the code i try in my servlet but it still continues with recieving the body before this doPost method is called. It seems that the stream is fully received before the servlet is invoked.

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    PrintWriter out = response.getWriter();
    response.setContentType("text/plain");
    if (request.getHeader("Authorization") == null) {
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        out.println("Status: " + HttpServletResponse.SC_UNAUTHORIZED + " - UNAUTHORIZED");
        return;
    }
    // ... the rests
}

回答1:

That's the limitation of HTTP. You can't send a response when the request hasn't been read fully to end.

回答2:

RFC 2616 says:

An HTTP/1.1 (or later) client sending a message-body SHOULD monitor the network connection for an error status while it is transmitting the request. If the client sees an error status, it SHOULD immediately cease transmitting the body.

So I disagree, this is not a HTTP limitation but a servlet one.

来源：https://stackoverflow.com/questions/4528778/how-to-drop-body-of-a-request-after-checking-headers-in-servlet

标签

java

servlets