博客

一、引子

有时候，我们相对返回数据做进一步处理，而 httpServletResponse 不允许我们读取其内容，所以我们需要对其自定义包装

二、自定义response wrapper

public class ResponseWrapper extends HttpServletResponseWrapper {
    private ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

    private PrintWriter printWriter = new PrintWriter(outputStream);

    public ResponseWrapper(HttpServletResponse response) {
        super(response);
    }

    @Override
    public ServletOutputStream getOutputStream() throws IOException {
        return new ServletOutputStream() {
            @Override
            public boolean isReady() {
                return false;
            }

            @Override
            public void setWriteListener(WriteListener writeListener) {

            }

            @Override
            public void write(int b) throws IOException {
                outputStream.write(b);
            }

            @Override
            public void write(byte[] b) throws IOException {
                outputStream.write(b);
            }

            @Override
            public void write(byte[] b, int off, int len) throws IOException {
                outputStream.write(b, off, len);
            }

            @Override
            public void flush() throws IOException {
                outputStream.flush();
            }
        };
    }

    @Override
    public PrintWriter getWriter() throws IOException {
        return printWriter;
    }

    public void flush(){
        try {
            printWriter.flush();
            printWriter.close();
            outputStream.flush();
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public byte[] getContent() {
        flush();
        return outputStream.toByteArray();
    }
}

三、使用

可以在过滤器中使用

protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
        String requestString = map2String(httpServletRequest.getParameterMap());
        String schema = httpServletRequest.getMethod();
        //自定义wrapper
        ResponseWrapper  responseWrapper = new ResponseWrapper(httpServletResponse);
        long start = System.currentTimeMillis();
        //使用新的wrapper
        filterChain.doFilter(httpServletRequest, responseWrapper);
        long end = System.currentTimeMillis();
        LOGGER.info(schema + COLON + httpServletRequest.getRequestURI() + QUESTION_MARK + requestString + "&consumer=" + (end - start));
        //读取wrapper中的内容
        byte[] bytes = responseWrapper.getContent();
        if (!isRequestPicture(httpServletRequest)){
            LOGGER.info(new String(bytes));
        }
        //将数据重新写入返回数据流中
        httpServletResponse.getOutputStream().write(bytes);
    }