如何在Filter中对ServletInputStream处理后（例如解Gzip压缩）让后续Servlet能够getParameter得到参数？
很简单的应用：客户端将XML报文用GZIP压缩后通过两个Parameter发送到服务器，用的POST方法，一个Parameter是“head”一个是“body”。我写了一个Filter来对request中的InputStream做解压动作。但是在Filter里面调用了request.getInputStream()方法后，接下来将request送给Servlet以后，request.getParameter("head")就取不到值了，但是request.getInputStream()能够取到解压后的InputStream。怎样才能让后续Servlet能够request.getParameter("head")取到值呢？
public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {HttpServletRequest req = (HttpServletRequest) request;req = getServletRequest(req);chain.doFilter(req, response);}private HttpServletRequest getServletRequest(final HttpServletRequest pRequest) {return new HttpServletRequestWrapper(pRequest) {public int getContentLength() {return -1;}public ServletInputStream getInputStream() throws IOException {final InputStream in = new GZIPInputStream(pRequest.getInputStream());return new ServletInputStream() {public int read() throws IOException {return in.read();}public void close() throws IOException {in.close();}};}public BufferedReader getReader() throws IOException {return new BufferedReader(new InputStreamReader(getInputStream(), "UTF-8"));}};}