getReader() has already been called

背景
代码
附录

解决方案参考这里

背景

项目中遇到一个需求：对 WEB 页面传递的参数进行校验
即：WEB 页面在传递参数的同时，会通过 Authorization 传递校验的 MD5；服务端在拿到参数之后也计算 MD5，如果和 WEB 页面传递的不同，则说明被篡改，校验不通过

这种需求肯定要用 Interceptor 或者 Filter 的，结果在增加校验之后，之前就存在的 Filter 报错了（完整错误见附录）：

java.lang.IllegalStateException: getReader() has already been called for this request

原来，新增的校验是通过request.getReader()方法获取的参数，之前就存在的 Filter 也使用该方法获取参数
但是，request.getReader()和request.getInputStream()只能调用一次，第二次调用即报上述错误

解决办法：先将 RequestBody 保存为一个 byte 数组，然后通过 Servlet 自带的 HttpServletRequestWrapper 类覆盖 getReader()和getInputStream() 方法，使流从保存的 byte 数组中读取，最后在 Filter 中将 ServletRequest 替换为 HttpServletRequestWrapper

代码

重写 HttpServletRequestWrapper

 import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.StringWriter;
 import javax.servlet.ReadListener;
 import javax.servlet.ServletInputStream;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletRequestWrapper;
	
 public class ParamHttpServletRequestWrapper extends HttpServletRequestWrapper {
	
     private byte[] body;
	
     public ParamHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
         super(request);
	
         BufferedReader reader = request.getReader();
         try (StringWriter writer = new StringWriter()) {
             int read;
             char[] buf = new char[1024 * 8];
             while ((read = reader.read(buf)) != -1) {
                 writer.write(buf, 0, read);
             }
             this.body = writer.getBuffer().toString().getBytes();
         }
     }
	
     public byte[] getBody() {
         return body;
     }
	
     @Override
     public javax.servlet.ServletInputStream getInputStream() throws IOException {
         ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body);
         return new ServletInputStream() {
	
             @Override
             public int read() throws IOException {
                 return byteArrayInputStream.read();
             }
	
             @Override
             public void setReadListener(ReadListener listener) {
                 this.setReadListener(listener);
             }
	
             @Override
             public boolean isReady() {
                 return false;
             }
	
             @Override
             public boolean isFinished() {
                 return false;
             }
         };
     }
 }

实现一个全局 Filter 将 HttpServletRequest 转换为 ParamHttpServletRequestWrapper

 import java.io.IOException;
 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
 import javax.servlet.FilterConfig;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServletRequest;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.stereotype.Component;
	
 @Component
 public class ParamFilter implements Filter {
	
     private Logger logger = LoggerFactory.getLogger(ParamFilter.class);
	
     @Override
     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
         logger.info("=== doFilter ===");
         if (request instanceof HttpServletRequest) {
             ServletRequest requestWrapper = new ParamHttpServletRequestWrapper((HttpServletRequest) request);
             chain.doFilter(requestWrapper, response);
         } else {
             chain.doFilter(request, response);
         }
     }
	
     @Override
     public void init(FilterConfig filterConfig) throws ServletException {
         logger.info("ParamFilter init ……");
     }
	
     @Override
     public void destroy() {
         logger.info("ParamFilter destroy ……");
     }
 }

实现一个 Interceptor 完成校验功能

 import com.alibaba.fastjson.JSONObject;
 import java.io.UnsupportedEncodingException;
 import java.net.URLDecoder;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.TreeMap;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.stereotype.Component;
 import org.springframework.web.servlet.HandlerInterceptor;
	
 @Component
 public class ParamCheckInterceptor implements HandlerInterceptor {
	
     private Logger logger = LoggerFactory.getLogger(ParamCheckInterceptor.class);
	
     @Override
     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
         logger.info("进入ParamCheckInterceptor……");
         String authorization = request.getHeader("Authorization");
         String md5 = null; // 从 authorization 中获取
         String param = getParam(request);
         String checkMd5 = null;// 根据 param 获取 md5
         return md5.equals(checkMd5);
     }
	
     private String getParam(HttpServletRequest request) throws UnsupportedEncodingException {
         Map<String, String> result = new HashMap<>();
         if ("POST".equals(request.getMethod())) {
             if (request instanceof ParamHttpServletRequestWrapper) {
                 ParamHttpServletRequestWrapper requestWrapper = (ParamHttpServletRequestWrapper) request;
                 String param = new String(requestWrapper.getBody());
                 if (StringUtils.isNotEmpty(param)) {
                     result = JSONObject.parseObject(param, Map.class);
                 }
             }
         } else if ("GET".equals(request.getMethod())) {
             String param = URLDecoder.decode(request.getQueryString(), "utf-8");
             String[] params = param.split("&");
             for (String s : params) {
                 Integer index = s.indexOf('=');
                 result.put(s.substring(0, index), s.substring(index + 1));
             }
         }
         TreeMap<String, Object> treeMap = new TreeMap(result);
         StringBuilder sb = new StringBuilder();
         for (Map.Entry<String, Object> entrySet : treeMap.entrySet()) {
             sb.append(entrySet.getKey()).append("=").append(entrySet.getValue().toString()).append("&");
         }
         if (sb.length() > 1) {
             sb.deleteCharAt(sb.length() - 1);
         }
         return sb.toString();
     }
 }

配置 Interceptor 的使用范围为全局

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
	
 @Component
 public class ParamCheckConfiguration implements WebMvcConfigurer {
	
     @Autowired
     private ParamCheckInterceptor paramCheckInterceptor;
	
     @Override
     public void addInterceptors(InterceptorRegistry registry) {
         registry.addInterceptor(paramCheckInterceptor).addPathPatterns("/**");
     }
 }

附录

完整错误：

2021-09-02 14:57:27,262 ERROR [http-nio-9681-exec-4] [mdm-DirectJDKLog.java:175]: Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: getReader() has already been called for this request] with root cause
java.lang.IllegalStateException: getReader() has already been called for this request
	at org.apache.catalina.connector.Request.getInputStream(Request.java:1049)
	at org.apache.catalina.connector.RequestFacade.getInputStream(RequestFacade.java:365)
	at org.springframework.http.server.ServletServerHttpRequest.getBody(ServletServerHttpRequest.java:211)
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver$EmptyBodyCheckingHttpInputMessage.<init>(AbstractMessageConverterMethodArgumentResolver.java:316)
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:193)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:157)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:130)
	at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:127)
	at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:167)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1039)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at ---自定义的---.CORSFilter.doFilter(CORSFilter.java:26)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:88)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:114)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:104)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:853)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)