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

時間 2020-02-17

標籤 java.lang.illegalstateexception java lang illegalstateexception getoutputstream response 欄目 Java 简体版

原文原文鏈接

1.問題描述：html

　　在導出數據庫某時間段的數據，而後得到Excel，雖然頁面能夠順利導出，但後臺報錯以下：（雖然不影響導出效果，但看到後臺的異常，心裏仍是不舒服的）java

嚴重: Servlet.service() for servlet [jsp] in context with path [/exportExcel] threw exception [java.lang.IllegalStateException: getOutputStream() has already been called for this response] with root cause
java.lang.IllegalStateException: getOutputStream() has already been called for this response
    at org.apache.catalina.connector.Response.getWriter(Response.java:678)
    at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:213)
    at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125)
    at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118)
    at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:194)
    at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:126)
    at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:80)
    at org.apache.jsp.export_jsp._jspService(export_jsp.java:566)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:439)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
    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)

　　從字義上分析：getOutputStream()已經調用了這個響應，就是重複被調用引發的異常。web

2.問題分析：數據庫

　　在tomcat下jsp出現該錯誤通常都是在使用了輸出流（如輸出圖片驗證碼，文件下載等）。apache

　　產生這樣的異常緣由：是web容器生成的servlet代碼中有out.write("")，這個和JSP中調用的response.getOutputStream()產生衝突。即Servlet規範說明，不能既調用response.getOutputStream()，又調用response.getWriter()，不管先調用哪個，在調用第二個時候應會拋出IllegalStateException，由於在jsp中，out變量其實是經過response.getWriter獲得的，你的程序中既用了response.getOutputStream，又用了out變量，故出現以上錯誤。緩存

3.解決方案：tomcat

　　在調用 response.getOutputStream()以前，清空緩存的內容，並返回一個新的BodyContext，更新PageContext的out屬性的內容。websocket

...
<body>
<%
    String startDate = request.getParameter("startDate");
    String endDate = request.getParameter("endDate");
    System.out.println("起始時間："+startDate+"  &&&  終止時間"+endDate);
    if(startDate== null || startDate.equals("")){
        startDate = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
        System.out.println("起始時間："+startDate);
    }
    if(endDate== null || endDate.equals("")){
        endDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
        System.out.println(endDate);
    }else{
        endDate = endDate+" 23:59:59";
        System.out.println("終止時間："+endDate);
    }
    String fileName = new Date().getTime()+".xls";
    response.reset();
    response.setContentType("application/vnd.ms-excel");
    response.setHeader("Content-disposition", "inline;filename="+fileName);
 out.clear(); //清空緩存的內容 out=pageContext.pushBody(); //更新PageContext的out屬性的內容
    writeExcel(response.getOutputStream(),startDate,endDate);
%>
</body>
</html>
<%!    //至關於全局聲明，是jsp頁面中一些變量和方法的聲明時用到的；上面沒有感嘆號的只是普通的語句 jsp代碼塊
    public static void writeExcel(OutputStream os,String startDate,String endDate){
        try{
            WritableWorkbook wwb = Workbook.createWorkbook(os);
            WritableSheet sheet = wwb.createSheet("導出表單", 0);  //第一個sheet
            // 設置字體
            WritableFont redfont = new WritableFont(WritableFont.createFont("微軟雅黑"),10, WritableFont.BOLD, false, UnderlineStyle.NO_UNDERLINE, Colour.RED);
            // **************往工做表中添加數據*****************
            WritableCellFormat red_key = new WritableCellFormat(redfont);
            WritableFont black_font = new WritableFont(WritableFont.createFont("微軟雅黑"),10, WritableFont.BOLD, false, UnderlineStyle.NO_UNDERLINE,Colour.BLACK);
            WritableCellFormat black_key = new WritableCellFormat(black_font);
            // **************往工做表中添加表頭*****************
...
...