java Filter过滤器获取响应数据

响应数据拦截

1、ResponseFilter

package com.ws.ldy.config.auth.filter;

import com.alibaba.fastjson.JSON;
import com.ws.ldy.config.auth.service.FilterService;
import com.ws.ldy.config.auth.wrapper.ResponseWrapper;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.lang.reflect.Method;

/**
 * 返回值输出过滤器，这里用来加密返回值
 *
 * @Title: ResponseFilter
 * @Description:
 * @author kokJuis
 * @date 上午9:52:42
 */
@Slf4j
public class ResponseFilter implements Filter {

    private FilterService filterService;

    public ResponseFilter(FilterService filterService) {
        this.filterService = filterService;
    }


    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        String uri = request.getRequestURI();
        //  1、排除
        Boolean aBoolean = filterService.excludeUri(uri);
        if (!aBoolean) {
            filterChain.doFilter(servletRequest, servletResponse);
            return;
        }
        // 转换成代理类
        ResponseWrapper wrapperResponse = new ResponseWrapper(response);
        // 这里只拦截返回，直接让请求过去，如果在请求前有处理，可以在这里处理
        filterChain.doFilter(request, wrapperResponse);
        // 返回值字节
        byte[] content = wrapperResponse.getContent();
        // 判断是否有值
        if (content.length <= 0) {
            return;
        }
        // 返回值
        String str = new String(content, "UTF-8");
        // 调用链
        if (!isJson(str)) {
            // 如果不是json数据,可能是返回的数据流或下载文件,直接返回原数据
            //把返回值输出到客户端
            ServletOutputStream out = response.getOutputStream();
            out.write(content);
            out.flush();
        } else {
            // 处理返回数据
            String cipherText = null;
            try {
                cipherText = str;
                //......根据需要处理返回值
            } catch (Exception e) {
                e.printStackTrace();
            }
            //把返回值输出到客户端
            ServletOutputStream out = response.getOutputStream();
            out.write(cipherText.getBytes());
            out.flush();
        }
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
    }


    @Override
    public void destroy() {

    }


    /**
     * 判断字符串数据是否为json
     * @param content
     * @return
     */
    public static boolean isJson(String content) {
        try {
            JSON.parseObject(content);
            return true;
        } catch (Exception e) {
            return false;
        }
    }
}

2、ResponseWrapper

package com.ws.ldy.config.auth.wrapper;


import java.io.ByteArrayOutputStream;
import java.io.IOException;

import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;


/**
 * 返回值输出代理类
 *
 * @Title: ResponseWrapper
 * @Description:
 * @author kokJuis
 * @date 上午9:52:11
 */
public class ResponseWrapper extends HttpServletResponseWrapper {

    private ByteArrayOutputStream buffer;

    private ServletOutputStream out;

    public ResponseWrapper(HttpServletResponse httpServletResponse) {
        super(httpServletResponse);
        buffer = new ByteArrayOutputStream();
        out = new WrapperOutputStream(buffer);
    }

    @Override
    public ServletOutputStream getOutputStream()
            throws IOException {
        return out;
    }

    @Override
    public void flushBuffer()
            throws IOException {
        if (out != null) {
            out.flush();
        }
    }

    public byte[] getContent()
            throws IOException {
        flushBuffer();
        return buffer.toByteArray();
    }

    class WrapperOutputStream extends ServletOutputStream {
        private ByteArrayOutputStream bos;

        public WrapperOutputStream(ByteArrayOutputStream bos) {
            this.bos = bos;
        }

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

        @Override
        public boolean isReady() {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public void setWriteListener(WriteListener arg0) {
            // TODO Auto-generated method stub
        }
    }
}

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