统一日志输出打印POST请求参数

众所周知，request.getInputStream()只能调一次。如果希望在请求进入Controller之前统一打印请求参数（拦截器或过滤器），又不影响业务，我们只能将获取到的输入流缓存起来，后续都从缓存中获取即可。

首先，自定义一个ServletInputStream

package com.cjs.example.log.filter;import javax.servlet.ReadListener;import javax.servlet.ServletInputStream;import java.io.ByteArrayInputStream;import java.io.IOException;/** * @Author: ChengJianSheng * @Date: 2023/3/6 */public class CustomServletInputStream extends ServletInputStream {    private ByteArrayInputStream inputStream;    public CustomServletInputStream(byte[] body) {        this.inputStream = new ByteArrayInputStream(body);    }    @Override    public boolean isFinished() {        return inputStream.available() == 0;    }    @Override    public boolean isReady() {        return true;    }    @Override    public void setReadListener(ReadListener readListener) {    }    @Override    public int read() throws IOException {        return inputStream.read();    }}

然后，自定义一个HttpServletRequestWrapper

package com.cjs.example.log.filter;import org.apache.commons.io.IOUtils;import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import java.io.*;/** * @Author: ChengJianSheng * @Date: 2023/3/6 */public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {    private byte[] body;    public CustomHttpServletRequestWrapper(HttpServletRequest request) throws IOException {        super(request);        body = IOUtils.toByteArray(request.getInputStream());    }    @Override    public ServletInputStream getInputStream() throws IOException {        return new CustomServletInputStream(body);    }    @Override    public BufferedReader getReader() throws IOException {        return new BufferedReader(new InputStreamReader(getInputStream(), getCharacterEncoding()));    }}

接下来，写一个过滤器，在过滤器中打印请求参数

package com.cjs.example.log.filter;import org.apache.commons.io.IOUtils;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import javax.servlet.*;import javax.servlet.http.HttpServletRequest;import java.io.IOException;/** * @Author: ChengJianSheng * @Date: 2023/3/6 */public class LogFilter implements Filter {    private final static Logger logger = LoggerFactory.getLogger(LogFilter.class);    @Override    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {        CustomHttpServletRequestWrapper requestWrapper = new CustomHttpServletRequestWrapper((HttpServletRequest) servletRequest);        printLog(requestWrapper);        filterChain.doFilter(requestWrapper, servletResponse);    }    private void printLog(CustomHttpServletRequestWrapper requestWrapper) throws IOException {        logger.info("请求URL: {}", requestWrapper.getRequestURL());        String method = requestWrapper.getMethod();        if ("GET".equalsIgnoreCase(method)) {            logger.info("请求参数: {}", requestWrapper.getQueryString());        } else if ("POST".equalsIgnoreCase(method) && "application/json".equalsIgnoreCase(requestWrapper.getContentType())) {            String body = IOUtils.toString(requestWrapper.getInputStream(), requestWrapper.getCharacterEncoding());            logger.info("请求参数: {}", body);        }    }}

请求经过过滤器的时候，首先在构造CustomHttpServletRequestWrapper的时候将请求中的InputStream转成字节数字缓存到内存中，然后后面每次再getInputStream()的时候都从缓存中取出内容并返回一个新的ServletInputStream

最后，定义一个配置类

package com.cjs.example.log.config;import com.cjs.example.log.filter.LogFilter;import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;/** * @Author: ChengJianSheng * @Date: 2023/3/6 */@Configurationpublic class CustomLogAutoConfiguration {    @Bean    @ConditionalOnMissingBean    public LogFilter logFilter() {        return new LogFilter();    }}

在resources/META-INF/spring.factories中新增一行自动配置

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.cjs.example.log.config.CustomLogAutoConfiguration