HttpServletRequestWrapper，HttpServletResponseWrapper的使用往往配合过滤器Filter使用，即  本文做一下记录一次用HttpServletResponseWrapper和拦截器来做输出压缩的过程

包装类

public class DatasWrapper extends HttpServletResponseWrapper {


  private   ByteArrayOutputStream outputStream;



    public byte[] getResponseData(){

        try {
            outputStream.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return outputStream.toByteArray();



     }





    public DatasWrapper(HttpServletResponse response) {
        super(response);
        this.outputStream =new ByteArrayOutputStream();

    }

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


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

            @Override
            public void setWriteListener(WriteListener listener) {

            }

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

 

做拦截的类，我这里这个类只想对结果做一下压缩输出，当然开启压缩可以直接在tomcat等容器的参数配置上配置，这个是代码级别来压缩

@WebFilter(filterName="gzip",urlPatterns = "/getZip.do")
public class GzipFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {


        if (shouldFilte(servletRequest)){
            DatasWrapper wrapper=new DatasWrapper((HttpServletResponse) servletResponse);
           filterChain.doFilter(servletRequest,wrapper);
            System.out.println("filter运行了");


            byte[] responseData = wrapper.getResponseData();


            byte[] gzip = gzip(responseData);

            System.out.println("------------------");
            System.out.println( "原来长度："+responseData.length);
            System.out.println("压缩后的长度:"+gzip.length);
            System.out.println("--------------------");

            HttpServletResponse response=(HttpServletResponse)servletResponse;

            System.out.println(gzip.length);
            System.out.println(Arrays.toString(gzip));

           response.setHeader(HttpHeaders.CONTENT_ENCODING,"gzip");
            response.setHeader(HttpHeaders.CONTENT_TYPE,"application/json;charset=utf-8");
            response.setContentLength(gzip.length);
            servletResponse.getOutputStream().write(gzip);
            servletResponse.getOutputStream().flush();

        }else {

            filterChain.doFilter(servletRequest,servletResponse);

        }









    }

    private byte[] gzip(byte[] responseData) throws IOException {

        ByteArrayOutputStream byteArrayOutputStream=new ByteArrayOutputStream();
        GZIPOutputStream outputStream=new GZIPOutputStream(byteArrayOutputStream);
        outputStream.write(responseData);
        outputStream.finish();
        outputStream.close();
        byte[] bytes = byteArrayOutputStream.toByteArray();
        byteArrayOutputStream.close();
        return bytes;



    }

    private boolean shouldFilte(ServletRequest servletRequest) {
        HttpServletRequest request=(HttpServletRequest)servletRequest;
        String requestURI = request.getRequestURI();
        if (requestURI.contains("/getZip.do")){
            return true;
        }
        return false;
    }

    @Override
    public void destroy() {

    }
}

此处用了

@WebFilter注解，要想被扫描到，需要在运行主类上加上@ServletComponentScan

 

HttpServletRequestWrapper的用法差不多

 

参考：这一篇文章写的不错，可做参考  https://blog.csdn.net/u011410529/article/details/78873404