java - 我收到 java.lang.IllegalStateException: getOutputStream() has already been called for this response 异常

Question

java.lang.IllegalStateException: getOutputStream() 已经为此响应调用

嗨，当我尝试通过我的 java 代码打开一个 pdf 文件时，我遇到了异常

这是我的Java代码。我正在使用 IText 创建 pdf

@RequestMapping(value = "/pdf", method = RequestMethod.POST)
public String pdf(ActivitiesForm activitiesForm, Model model,
        HttpSession session,HttpServletResponse response) throws InstanceNotFoundException, IOException,
        DocumentException {

    String PATH = "/home/space/workspace/trainning/Trainning/Performance.pdf";
    // step 1
    Document document = new Document();
    // step 2
     FileOutputStream fos = new FileOutputStream(PATH);
    PdfWriter.getInstance(document,fos);
    // step 3
    document.open();
    // step 4
    PdfPTable table;

    table = new PdfPTable(3);
    table.setWidthPercentage(100);
    PdfPCell cell;

    cell = new PdfPCell(new Phrase("Roll No"));
    cell.setColspan(1);
    // cell.setBorder(Rectangle.NO_BORDER);
    table.addCell(cell);
    cell = new PdfPCell(new Phrase("Name"));
    cell.setColspan(1);
    // cell.setBorder(Rectangle.NO_BORDER);
    table.addCell(cell);
    cell = new PdfPCell(new Phrase("Performance"));
    cell.setColspan(1);
    // cell.setBorder(Rectangle.NO_BORDER);
    table.addCell(cell);

    Integer count = rollService.getRollCount();
    Integer countpts = creditptsService.getPtsCount();

    if (countpts != null) {
        for (Integer i = 1; i <= count; i++) {
            Roll roll = rollService.getRollNoById(Long.parseLong(i
                    .toString()));

            List<Creditpts> creditpts = creditptsService.getRollById(roll
                    .getId());

            Integer performance = 0;

            if (creditpts == null) {

                cell = new PdfPCell(new Phrase("" + roll.getRollno()));
                cell.setColspan(1);
                // cell.setBorder(Rectangle.NO_BORDER);
                table.addCell(cell);

                cell = new PdfPCell(new Phrase("" + roll.getStudentName()));
                cell.setColspan(1);
                // cell.setBorder(Rectangle.NO_BORDER);
                table.addCell(cell);

                cell = new PdfPCell(new Phrase("0"));
                cell.setColspan(1);
                // cell.setBorder(Rectangle.NO_BORDER);
                table.addCell(cell);

            } else {
                Iterator<Creditpts> creIterator = creditpts.iterator();

                while (creIterator.hasNext()) {
                    Creditpts creditpt = creIterator.next();

                    performance += creditpt.getCrdpts();
                }

                cell = new PdfPCell(new Phrase("" + roll.getRollno()));
                cell.setColspan(1);
                // cell.setBorder(Rectangle.NO_BORDER);
                table.addCell(cell);

                cell = new PdfPCell(new Phrase("" + roll.getStudentName()));
                cell.setColspan(1);
                // cell.setBorder(Rectangle.NO_BORDER);
                table.addCell(cell);

                cell = new PdfPCell(new Phrase("" + performance));
                cell.setColspan(1);
                // cell.setBorder(Rectangle.NO_BORDER);
                table.addCell(cell);

            }
        }
    }
    document.add(table);
    document.close();

    fos.close();
    FileInputStream baos = new FileInputStream(PATH);

    // set some response headers
    response.setHeader("Expires", "0");
    response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
    response.setHeader("Pragma", "public");
    response.setContentType("application/pdf");

    response.setContentLength((int) new File(PATH).length());
    OutputStream os = response.getOutputStream();
    byte buffer[] = new byte[8192];
    int bytesRead, i;

    while ((bytesRead = baos.read(buffer)) != -1) {
        os.write(buffer, 0, bytesRead);
    }
    os.flush();
    os.close();
}

我已经粘贴了我的 pdf 创建和打开代码我在这里做错了什么我错过了一些东西......

这是完整的堆栈跟踪：

java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:633)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:214)
at javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:105)
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.JspWriterImpl.write(JspWriterImpl.java:336)
at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:353)
at org.apache.jsp.jsp.activity_jsp._jspService(activity_jsp.java:402)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:593)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:530)
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:229)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:262)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1265)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1016)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:965)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:859)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:883)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:792)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:928)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:298)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)

score 3 · Accepted Answer

Add the following inside the end of the try/catch to avoid the error that appears when the JSP engine flushes the response via getWriter()

out.clear(); // where out is a JspWriter
out = pageContext.pushBody();

This isn't best practice, but it avoids the errors in your logs. Ideally we should do this in Servlet and not in JSP. If you still needs it in JSP, follow above code to get rid off the error.

score 2 · Accepted Answer

您完全在 java 代码中处理请求，然后 Spring/container 的功能开始尝试通过呈现一些 jsp 来处理相同的请求。在这种特殊情况下，您需要禁用此功能。

score 0 · Accepted Answer

正如您在堆栈跟踪中看到的，JSP 调用了 response.getWriter()，但异常消息表明之前调用了 response.getOutputStream()。您不能在同一个响应对象上调用这两种方法。

检查以下链接：

https://stackoverflow.com/a/3540474/2333119

和

https://stackoverflow.com/a/14951581/2333119

java - 我收到 java.lang.IllegalStateException: getOutputStream() has already been called for this response 异常

3 回答 3

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