Question

I am trying to create a request log for my web app. I am using Spring 3.
0.

I implemented a class extending HandlerInterceptorAdapter and used the preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) to intercept the request.

In the method i want to be able to log the request body (my parameters are objects in XML that are written directly to the request body), and for that i use request.getReader();

The problem is – later on I will get an IllegalStateException when the spring controller tries to read the request.

Is there a way to do what I intend?

Answer 1

You can do this with a filter. The request parameters are easy to handle.
However dealing with the request body will be much more difficult
and will require wrapping the servlet request see: HttpServletRequest.

You will need to look how big the incoming request is and decide whether you want to store the request body as a tmp file or string.

You will need to override ServetRequest.getInputStream() with your file or saved string that used for logging.

If the request body is huge I recommend putting the input stream into a buffered input stream and then reading the start of the body.

public class LogRequest extends HttpServletRequestWrapper {

    public LogRequest(HttpServletRequest request) {
        super(request);
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        //read from tmp file or string.
    }

    @Override
    public BufferedReader getReader() throws IOException {
        //read from tmp file or string
    }

}