如何优雅的打印项目日志

框架
springboot

原理

使用filter拦截请求，打印出请求、响应，及耗时

知识点
1、OncePerRequestFilter

Filter base class that aims to guarantee a single execution per request dispatch, on any servlet container.Filter base class that aims to guarantee a single execution per request dispatch, on any servlet container.
过滤器基类，旨在保证在任何 servlet 容器上每个请求调度一次执行。

兼容多种servlet版本，保证在任何 servlet 容器上每个请求调度一次执行。

2、ContentCachingRequestWrapper，ContentCachingResponseWrapper
HttpServletRequest 包装器，用于缓存从输入流和读取器读取的所有内容，并允许通过字节数组检索此内容。
源代码如下，第一次获取输入流时，复制了一份

因为request的数据流只能读取一次，通过过滤器读取一次后，后面的业务处理会读不到数据
通过ContentCachingRequestWrapper将请求包装，可以进行多次读取

实现

继承OncePerRequestFilter，重写doFilterInternal方法

日志打印Filter

import com.google.common.base.Throwables;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.MediaType;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.util.ContentCachingRequestWrapper;
import org.springframework.web.util.ContentCachingResponseWrapper;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Enumeration;

@Slf4j
public class LogFilter extends OncePerRequestFilter {

    private Integer printMaxSize;

    public LogFilter() {
    }

    public LogFilter(Integer printMaxSize) {
        if (printMaxSize == null) {
            printMaxSize = 1024;
        }
        this.printMaxSize = printMaxSize;
    }

    @Override
    protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {

        if (isAsyncDispatch(httpServletRequest)) {
            filterChain.doFilter(httpServletRequest, httpServletResponse);
        } else {
            doLogFilter(getRequestWrapper(httpServletRequest), getResponseWrapper(httpServletResponse), filterChain);
        }
    }

    private void doLogFilter(ContentCachingRequestWrapper requestWrapper, ContentCachingResponseWrapper responseWrapper, FilterChain filterChain) throws IOException, ServletException {
        StringBuilder sb = new StringBuilder();
        sb.append(System.lineSeparator())
                .append("Method: [").append(requestWrapper.getMethod()).append("] ")
                .append("URI: ").append(requestWrapper.getRequestURI())
                .append(System.lineSeparator());
        long start = System.currentTimeMillis();

        filterChain.doFilter(requestWrapper, responseWrapper);

        try {
            sb.append(getParams(requestWrapper)).append(System.lineSeparator());
            sb.append(getBody(requestWrapper));
            sb.append(getResponse(responseWrapper)).append(System.lineSeparator());
        } catch (Exception e) {
            log.warn("日志打印失败 e:{}", Throwables.getStackTraceAsString(e));
        } finally {
            responseWrapper.copyBodyToResponse();
            long end = System.currentTimeMillis();
            sb.append("use time :").append(end - start).append("ms");
            log.info(sb.toString());
        }
    }

    private String getBody(ContentCachingRequestWrapper requestWrapper) {
        StringBuilder sb = new StringBuilder();
        String contentType = requestWrapper.getContentType();
        if (requestWrapper.getMethod().equalsIgnoreCase("POST")
                && (MediaType.APPLICATION_JSON_VALUE.equals(contentType)
                || MediaType.APPLICATION_JSON_UTF8_VALUE.equals(contentType))) {
            sb.append("body: ").append(System.lineSeparator());
            sb.append(new String(requestWrapper.getContentAsByteArray(), StandardCharsets.UTF_8));
            sb.append(System.lineSeparator());
        }
        return sb.toString();
    }

    private String getResponse(ContentCachingResponseWrapper responseWrapper) {
        String responseStr = new String(responseWrapper.getContentAsByteArray(), StandardCharsets.UTF_8);
        responseStr = responseStr.length() > printMaxSize ? responseStr.substring(0, printMaxSize) : responseStr;
        return "response: " + responseStr;
    }

    private String getParams(ContentCachingRequestWrapper requestWrapper) {
        Enumeration<String> enumeration = requestWrapper.getParameterNames();
        StringBuilder sb = new StringBuilder();
        sb.append("params: ");
        while (enumeration.hasMoreElements()) {
            String paramName = enumeration.nextElement();
            sb.append(paramName);
            sb.append(" : ");
            sb.append(requestWrapper.getParameter(paramName));
            sb.append(", ");
        }
        if (sb.length() > 2) {
            sb.replace(sb.length() - 2, sb.length(), "");
        }
        return sb.toString();
    }

    private ContentCachingResponseWrapper getResponseWrapper(HttpServletResponse httpServletResponse) {
        if (httpServletResponse instanceof ContentCachingResponseWrapper) {
            return (ContentCachingResponseWrapper) httpServletResponse;
        } else {
            return new ContentCachingResponseWrapper(httpServletResponse);
        }
    }

    private ContentCachingRequestWrapper getRequestWrapper(HttpServletRequest httpServletRequest) {
        if (httpServletRequest instanceof ContentCachingRequestWrapper) {
            return (ContentCachingRequestWrapper) httpServletRequest;
        } else {
            return new ContentCachingRequestWrapper(httpServletRequest, printMaxSize);
        }
    }
}

注入容器

@Configuration
public class FilterConfig {

    /**
     * 日志长度限制
     */
    private Integer printMaxSize = 1024;

    @Bean
    public LogFilter getLogFilter() {
        return new LogFilter(printMaxSize);
    }

}