java.lang.IllegalStateException: getOutputStream() has already been called for this response

水深无声 2022-12-29 09:54 131阅读 0赞

### 目录 ###

*   *  背景
     *  原因分析
     *  解决方案

## 背景 ##

*  写一个合并2个excel功能，合并后导出新的excel的需求，代码如下所示。

@RequestMapping("/import")
        public String importFile(@RequestParam("userFile") MultipartFile userFile, @RequestParam("customerFile") MultipartFile customerFile, HttpServletResponse response) { 
            try { 
                ...省略...
                Workbook workbook = userFlowExportServiceImpl.userFlowExportExcel(excelTemplate);
                LocalDateTime now = LocalDateTime.now();
                DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
                String formatDateTime = now.format(formatter);
                response.setHeader("Content-Disposition", "attachment;filename=" + formatDateTime +".xlsx");
                response.setContentType("application/vnd.ms-excel;charset=UTF-8");
                response.setHeader("Pragma", "no-cache");
                response.setHeader("Cache-Control", "no-cache");
                response.setDateHeader("Expires", 0);
                BufferedOutputStream bufferedOutPut = new BufferedOutputStream(response.getOutputStream());
                workbook.write(bufferedOutPut);
                bufferedOutPut.flush();
                bufferedOutPut.close();
                log.info("完成");
                return "index";
            } catch (Exception e) { 
                e.printStackTrace();
            }
            return "index";
        }

*  导出excel功能可以正常完成，不过控制台报错，报错提示如下所示。

java.lang.IllegalStateException: getOutputStream() has already been called for this response
    	at org.apache.catalina.connector.Response.getWriter(Response.java:583) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:227) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:360) ~[thymeleaf-spring5-3.0.11.RELEASE.jar:3.0.11.RELEASE]
    	at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:189) ~[thymeleaf-spring5-3.0.11.RELEASE.jar:3.0.11.RELEASE]
    	at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1372) ~[spring-webmvc-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1118) ~[spring-webmvc-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1057) ~[spring-webmvc-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:94) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.16.RELEASE.jar:5.1.16.RELEASE]
    	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_171]
    	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_171]
    	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.36.jar:9.0.36]
    	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_171]

## 原因分析 ##

*  简单翻译`getOutputStream() has already been called for this response`，大意是`getOutputStream()`已经被调用过了，类似一个重复调用的问题。
 *  下面引出Servlet规范说明：`不能既调用response.getOutputStream()，又调用response.getWriter(),无论先调用哪一个，在调用第二个时候应会抛出IllegalStateException`，因为在jsp中，out变量实际上是通过response.getWriter()得到的，程序中既用了response.getOutputStream()，又用了out变量。
 *  然后现在来找找代码是否违反了Servlet规范：
    
     *  1、从上面代码可以看出，在`controller`层调用了`response.getOutputStream()`方法。
     *  2、查看报错提示的调用链，定位到Thymeleaf（我使用的是Thymeleaf模板引擎），的确调用过`response.getWriter()`方法，如下图所示。  
        ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzE5NDczNTI5_size_16_color_FFFFFF_t_70]  
        ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzE5NDczNTI5_size_16_color_FFFFFF_t_70 1]

## 解决方案 ##

*  不要返回值，不返回页面，那就不会进入Thymeleaf response.getWriter()的代码了，修改后的代码如下所示。

@RequestMapping("/import")
        public void importFile(@RequestParam("userFile") MultipartFile userFile, @RequestParam("customerFile") MultipartFile customerFile, HttpServletResponse response) { 
            try { 
                ...省略...
                Workbook workbook = userFlowExportServiceImpl.userFlowExportExcel(excelTemplate);
                LocalDateTime now = LocalDateTime.now();
                DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
                String formatDateTime = now.format(formatter);
                response.setHeader("Content-Disposition", "attachment;filename=" + formatDateTime +".xlsx");
                response.setContentType("application/vnd.ms-excel;charset=UTF-8");
                response.setHeader("Pragma", "no-cache");
                response.setHeader("Cache-Control", "no-cache");
                response.setDateHeader("Expires", 0);
                BufferedOutputStream bufferedOutPut = new BufferedOutputStream(response.getOutputStream());
                workbook.write(bufferedOutPut);
                bufferedOutPut.flush();
                bufferedOutPut.close();
                log.info("完成");
             
            } catch (Exception e) { 
                e.printStackTrace();
            }
         
        }

*  注意：该解决方案，仅适用于当前场景，主要是希望能提供一种思路，还需具体情况具体分析。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzE5NDczNTI5_size_16_color_FFFFFF_t_70]: /images/20221120/da0fd9040e2c4dbf847ac6239ec09fb3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzE5NDczNTI5_size_16_color_FFFFFF_t_70 1]: /images/20221120/a0363c0c0fb046cba34b9742a30c5de0.png