在Spring MVC或Spring Boot中使用Filter打印请求参数问题javaJava技术分享-

 使用Spring MVC或Spring Boot中打印或记录日志一般使用AOP记录Request请求和Response响应参数，在不使用AOP的前提下，如果在Filter中打印日志，在打印或消费请求类型为Content-Type:application/json的请求时，会出现严重的问题。

在Spring体系中，过滤器的定义我们一般采用继承OncePerRequestFilter的方式，当然也可以使用原始的Filter。

错误写法一：

如果不对request和response进行处理，使用伪代码采用如下写法打印请求和响应参数（注：此时request请求类型为Post，接收的是Json数据）

     @Override     protected void doFilterInternal(HttpServletRequest request, HttpServletResponse                                response, FilterChain filterChain) throws ServletException, IOException {         filterChain.doFilter(request, response);         printRequestLog(request);         printResonseLog(response);     }

       运行测试后你会发现抛出如下异常： 

 java.io.IOException: Stream closed  at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:359) ~[tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:132) ~[tomcat-embed-core-9.0.31.jar:9.0.31]  at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284) ~[na:1.8.0_191]  at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326) ~[na:1.8.0_191]  at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178) ~[na:1.8.0_191]  at java.io.InputStreamReader.read(InputStreamReader.java:184) ~[na:1.8.0_191]  at java.io.BufferedReader.fill(BufferedReader.java:161) ~[na:1.8.0_191]  at java.io.BufferedReader.readLine(BufferedReader.java:324) ~[na:1.8.0_191]  at java.io.BufferedReader.readLine(BufferedReader.java:389) ~[na:1.8.0_191]  at com.micro.backend.filter.LoggingFilter.getBodyString(LoggingFilter.java:60) [classes/:na]  at com.micro.backend.filter.LoggingFilter.doFilterInternal(LoggingFilter.java:49) [classes/:na]  at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:94) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.1.14.RELEASE.jar:5.1.14.RELEASE]  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1639) [tomcat-embed-core-9.0.31.jar:9.0.31]  at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.31.jar:9.0.31]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]  at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.31.jar:9.0.31]  at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191] 

错误写法二：

如果不对request和response进行处理，使用伪代码采用如下写法打印请求和响应参数（注：此时request请求类型为Post，接收的是Json数据）

     @Override     protected void doFilterInternal(HttpServletRequest request, HttpServletResponse                response, FilterChain filterChain) throws ServletException, IOException {         printRequestLog(request);         printResonseLog(response);         filterChain.doFilter(request, response);     }

       运行测试后你会发现抛出如下异常：  

 org.springframework.http.converter.HttpMessageNotReadableException: Required request body is missing

       遇到这样的问题你是不是有坐立不安、心烦意乱、百爪挠心的痛楚，不要着急，下面我给出一个解决方案。

       首先我们使用装饰器模式，创建request和response两个包装类，如下：

 import javax.servlet.ReadListener; import javax.servlet.ServletInputStream; import javax.servlet.ServletRequest; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import java.io.*; import java.nio.charset.Charset; /** * @Description:    请求包装器 * @Author:         liuliya * @CreateDate:     2020/4/29 10:00 */ public class RequestWrapper extends HttpServletRequestWrapper {          private final byte[] body;      public RequestWrapper(HttpServletRequest request) throws IOException {         super(request);         body = getRequestBodyString(request).getBytes(Charset.defaultCharset());     }      @Override     public BufferedReader getReader() throws IOException {         return new BufferedReader(new InputStreamReader(getInputStream()));     }      @Override     public ServletInputStream getInputStream() throws IOException {          final ByteArrayInputStream bais = new ByteArrayInputStream(body);          return new ServletInputStream() {              @Override             public int read() throws IOException {                 return bais.read();             }              @Override             public boolean isFinished() {                 return false;             }              @Override             public boolean isReady() {                 return false;             }              @Override             public void setReadListener(ReadListener listener) {              }         };     }      public String getRequestBodyString(ServletRequest request) {         StringBuilder sb = new StringBuilder();         InputStream inputStream = null;         BufferedReader reader = null;         try {             inputStream = request.getInputStream();             reader = new BufferedReader(new InputStreamReader(inputStream, Charset.defaultCharset()));             String line;             while ((line = reader.readLine()) != null) {                 sb.append(line);             }         } catch (IOException e) {             e.printStackTrace();         } finally {             if (inputStream != null) {                 try {                     inputStream.close();                 } catch (IOException e) {                     e.printStackTrace();                 }             }             if (reader != null) {                 try {                     reader.close();                 } catch (IOException e) {                     e.printStackTrace();                 }             }         }         return sb.toString();     }  }

 package com.micro.backend.filter.support;  import org.apache.commons.io.output.TeeOutputStream;  import javax.servlet.ServletOutputStream; import javax.servlet.ServletResponse; import javax.servlet.WriteListener; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpServletResponseWrapper; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.PrintWriter;  /**  * @Description: 响应包装器  * @Author: liuliya  * @CreateDate: 2020/4/29 10:00  */ public class ResponseWrapper extends HttpServletResponseWrapper {      private final ByteArrayOutputStream bos = new ByteArrayOutputStream();     private PrintWriter writer = new PrintWriter(bos);      public ResponseWrapper(HttpServletResponse response) {         super(response);     }      @Override     public ServletResponse getResponse() {         return this;     }      @Override     public ServletOutputStream getOutputStream() throws IOException {         return new ServletOutputStream() {             @Override             public boolean isReady() {                 return false;             }              @Override             public void setWriteListener(WriteListener listener) {              }              private TeeOutputStream tee = new TeeOutputStream(ResponseWrapper.super.getOutputStream(), bos);              @Override             public void write(int b) throws IOException {                 tee.write(b);             }         };     }      @Override     public PrintWriter getWriter() throws IOException {         return new TeePrintWriter(super.getWriter(), writer);     }      public byte[] toByteArray() {         return bos.toByteArray();     }  }  package com.micro.backend.filter.support;  import java.io.PrintWriter; //PrintWriter是一种写入字符的一种操作类，可以写入字符，TeePrintWriter继承了他，主要功能是把原始的字符流copy到branch里面。 public class TeePrintWriter extends PrintWriter {      PrintWriter branch;      public TeePrintWriter(PrintWriter main, PrintWriter branch) {         super(main, true);         this.branch = branch;     }      public void write(char buf[], int off, int len) {         super.write(buf, off, len);         super.flush();         branch.write(buf, off, len);         branch.flush();     }      public void write(String s, int off, int len) {         super.write(s, off, len);         super.flush();         branch.write(s, off, len);         branch.flush();     }      public void write(int c) {         super.write(c);         super.flush();         branch.write(c);         branch.flush();     }      public void flush() {         super.flush();         branch.flush();     } } 

接下来创建最重要的LoggingFilter类，继承OncePerRequestFilter，或者直接继承Servlet中原始的Filter。

 package com.micro.backend.filter;  import com.micro.backend.filter.support.RequestWrapper; import com.micro.backend.filter.support.ResponseWrapper; import lombok.extern.slf4j.Slf4j; import org.springframework.context.annotation.Configuration; import org.springframework.web.filter.OncePerRequestFilter;  import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; import java.io.UnsupportedEncodingException;  /** * @Author:         liuliya * @CreateDate:     2020/4/28 23:30 */ @Slf4j @Configuration public class LoggingFilter extends OncePerRequestFilter {         private static final String REQUEST_PREFIX_NAME = "Request请求: ";     private static final String RESPONSE_PREFIX_NAME = "Response请求: ";      @Override     protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {         request = new RequestWrapper(request);         response = new ResponseWrapper(response);         filterChain.doFilter(request, response);         printRequestLog(request);         printResponseLog((ResponseWrapper) response);     }      private void printRequestLog(final HttpServletRequest request) {         StringBuilder msg = new StringBuilder();         msg.append(REQUEST_PREFIX_NAME);         HttpSession session = request.getSession(false);         if (session != null) {             msg.append("sessionId = ").append(session.getId()).append("; ");         }         if (request.getMethod() != null) {             msg.append("method = ").append(request.getMethod()).append("; ");         }         if (request.getContentType() != null) {             msg.append("contentType = ").append(request.getContentType()).append("; ");         }         msg.append("uri = ").append(request.getRequestURI());         if (request.getQueryString() != null) {             msg.append('?').append(request.getQueryString());         }          if (request instanceof RequestWrapper && !isMultipart(request) && !isBinaryContent(request)) {             RequestWrapper requestWrapper = (RequestWrapper) request;             msg.append("; payload = ").append(requestWrapper.getRequestBodyString(request));         }         log.info(msg.toString());     }      private boolean isBinaryContent(final HttpServletRequest request) {         if (request.getContentType() == null) {             return false;         }         return request.getContentType().startsWith("image")                 || request.getContentType().startsWith("video")                 || request.getContentType().startsWith("audio");     }      private boolean isMultipart(final HttpServletRequest request) {         return request.getContentType() != null                 && request.getContentType().startsWith("multipart/form-data");     }      private void printResponseLog(final ResponseWrapper response) {         StringBuilder msg = new StringBuilder();         msg.append(RESPONSE_PREFIX_NAME);         try {             msg.append("; payload = ")                     .append(new String(response.toByteArray(), response.getCharacterEncoding()));         } catch (UnsupportedEncodingException e) {             log.warn("Failed to parse response payload", e);         }         log.info(msg.toString());     }  } 

参考以上我整理出的代码，你就会发现奇迹！！！

为什么要这么写呢，其本质是把请求流拷贝了一份，一个供filterChain向下传递，一个来做流的消费，再有一个就是运用装饰器模式的精髓所在。