打印HTTP request body和response body实现日志跟踪

request 的inputStream和response 的outputStream默认情况下是只能读一次， 不可重复读；这就导致要获取请求体或者响应体信息时必须要声明包裹类wrapper; spring为此提供了两个对应的包裹类ContentCachingRequestWrapper和ContentCachingResponseWrapper使得这两个流信息可重复读；

可以利用这两个类结合spring的WebUtil工具类来实现日志跟踪：

import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.util.ContentCachingRequestWrapper;
import org.springframework.web.util.ContentCachingResponseWrapper;
import org.springframework.web.util.WebUtils;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.UUID;

/**
 * @author: liumengbing
 * @date: 2019/03/12 10:10
 **/
@Component
@Slf4j
@WebFilter("/*")
public class WebLogFilter extends OncePerRequestFilter {

    private static Logger log = LoggerFactory.getLogger(WebLogFilter.class);

    public static final String SPLIT_STRING_M = "=";

    public static final String SPLIT_STRING_DOT = ", ";


    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        //日志trade
        MDC.clear();
        //使用唯一ID标识每次请求
        MDC.put("trade_id", UUID.randomUUID().toString().replaceAll("-",""));
        ContentCachingRequestWrapper wrapperRequest = new ContentCachingRequestWrapper(request);
        ContentCachingResponseWrapper wrapperResponse = new ContentCachingResponseWrapper(response);

        String urlParams = getRequestParams(request);
        log.info("request params[{}]", urlParams);
        filterChain.doFilter(wrapperRequest, wrapperResponse);

        String requestBodyStr = getRequestBody(wrapperRequest);
        log.info("request body:{}", requestBodyStr);

        String responseBodyStr = getResponseBody(wrapperResponse);

        log.info("response body:{}", responseBodyStr);
        wrapperResponse.copyBodyToResponse();
    }

    /**
     * 获取请求地址上的参数
     * @param request
     * @return
     */
    public static String getRequestParams(HttpServletRequest request) {
        StringBuilder sb = new StringBuilder();
        Enumeration<String> enu = request.getParameterNames();
        //获取请求参数
        while (enu.hasMoreElements()) {
            String name = enu.nextElement();
            sb.append(name + SPLIT_STRING_M).append(request.getParameter(name));
            if(enu.hasMoreElements()) {
                sb.append(SPLIT_STRING_DOT);
            }
        }
        return sb.toString();
    }

    /**
     * 打印请求参数
     * @param request
     */
    private String getRequestBody(ContentCachingRequestWrapper request) {
        ContentCachingRequestWrapper wrapper = WebUtils.getNativeRequest(request, ContentCachingRequestWrapper.class);
        if(wrapper != null) {
            byte[] buf = wrapper.getContentAsByteArray();
            if(buf.length > 0) {
                String payload;
                try {
                    payload = new String(buf, 0, buf.length, wrapper.getCharacterEncoding());
                } catch (UnsupportedEncodingException e) {
                    payload = "[unknown]";
                }
                return payload.replaceAll("\\n","");
            }
        }
        return "";
    }

    /**
     * 打印返回参数
     * @param response
     */
    private String getResponseBody(ContentCachingResponseWrapper response) {
        ContentCachingResponseWrapper wrapper = WebUtils.getNativeResponse(response, ContentCachingResponseWrapper.class);
        if(wrapper != null) {
            byte[] buf = wrapper.getContentAsByteArray();
            if(buf.length > 0) {
                String payload;
                try {
                    payload = new String(buf, 0, buf.length, wrapper.getCharacterEncoding());
                } catch (UnsupportedEncodingException e) {
                    payload = "[unknown]";
                }
                return payload;
            }
        }
        return "";
    }

}

在以上代码中还有一个技术点：使用了slf4j的MDC来跟踪请求信息，打印完整的请求处理日志；并在日志配置中加上了唯一ID，从而达到日志追踪的目的。

日志配置文件：

[%X{trade_id}]%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n

输出的日志信息：

[16fbd9304e23492cab3ccabb6a85d0c0]2019-03-12 10:40:49.127  INFO 13712 --- [nio-8188-exec-1] xxx.xx.xx.filter.WebLogFilter       : request params[{}]：account=xxxxx,  v_code=056036}
[16fbd9304e23492cab3ccabb6a85d0c0]2019-03-12 10:40:49.130  INFO 13712 --- [nio-8188-exec-1] xxx.xx.xx.filter.WebLogFilter       : request body:{}：{    "account":"xxxxx",  "v_code":"056036"}
[16fbd9304e23492cab3ccabb6a85d0c0]2019-03-12 10:40:49.131  INFO 13712 --- [nio-8188-exec-1] xxx.xx.xx.filter.WebLogFilter       : response body:{}：{"code":1,"msg":"请输入正确的验证码","data":"","success":false}