http://blog.csdn.net/xxj_jing/article/details/71177306
springmvc+filter 替換輸出流、response、響應(yīng)內(nèi)容
1.問題
1.描述：在使用 filter 替換、修改 response 輸出內(nèi)容時(shí)常見的錯(cuò)誤如下異常提示
getWriter() has already been called for this response
getOutputStream() has already been called for this response
2.問題產(chǎn)生原因：
getWriter() 和 getOutputStream() 方法互斥，一個(gè) response 只允許調(diào)用一次；
getWriter() 對(duì)應(yīng)一個(gè)字符流，用于處理純文本相關(guān)的資源；
getOutputStream() 對(duì)應(yīng)一個(gè)字節(jié)流，用于處理如圖片之類的資源；
3.解決辦法：
自定義一個(gè)包裝器繼承 HttpServletResponseWrapper 類，并且重寫以下兩個(gè)方法,且兩個(gè)方法都向同一個(gè)輸出流中寫入內(nèi)容；
public PrintWriter getWriter();
public PrintWriter getOutputStream();
報(bào)錯(cuò)日志：
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:625)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:211)
at javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:109)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:396)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:309)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:257)
at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:165)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:870)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:728)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:590)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:524)
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:162)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:870)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
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:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at com.easy.springboot.demo_spring_mvc.filter.AuthenticationFilter.doFilter(AuthenticationFilter.kt:24)
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:107)
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:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
