使用 PrintWriter 和 OutputStream

Question

我正在使用 struts 创建一个项目，但在使用 Jasper IReports 时遇到问题。我想将一些信息导出到 pdf 文件中，但我不断收到 java.lang.IllegalStateException：getOutputStream() 已被调用...当页面已经打开 PrintWriter 时，由于在我的代码中打开 ServletOutputStream 而出现异常。

代码位于模型中（因此它不在jsp中，而是在java文件中），如下所示：

    public void handle(HttpServletResponse res, Connection connection, String path)throws Exception{
    ServletOutputStream out = null;
    try {

        JasperDesign jasperDesign = JRXmlLoader.load(path);
        JasperReport jasperReport = JasperCompileManager.compileReport(jasperDesign);
        byte[] bytes = JasperRunManager.runReportToPdf(jasperReport, null, connection);
        res.setContentType("application/pdf");
        res.setContentLength(bytes.length);
        out = res.getOutputStream();
        out.write(bytes, 0, bytes.length);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        out.flush();
        out.close();
    }

我已经检查了连接、路径和 HttpServletResponse，一切都工作正常。

我是 Jasper Reports 以及将内容编码为 PDF 的新手，所以你可以正确地假设我对我在这里所做的事情有一个最低限度的了解，显然我的代码是通过网络从某个地方复制/粘贴的。

我尝试使用 PrintWriter 而不是 OutputStream，将字节转换为字符串并使用 PrintWriter.append(String) 方法（allthought 不是 String 是 CharSequence），但它不会将数据提取到 PDF 中。

我还尝试获取 PrintWriter，关闭它以打开 OutputStream （不起作用）或刷新它（两者都不是）。

任何有关使用任何可以在 pdf 中显示数据的输出的解决方案的帮助都会很棒。多谢！

Answer 1

将是有用的，看堆栈跟踪。

您可以尝试运行的完整性检查第一，虽然：修改代码，简单地写一个静态的字符串（你好世界）的ServletOutputStream的，并设置内容类型为text / html。作为应该很好地工作：

public void handle(HttpServletResponse res, Connection connection, String path)throws Exception{
ServletOutputStream out = null;
try {
    byte[] bytes = "hello world".getBytes();
    res.setContentType("text/html");
    res.setContentLength(bytes.length);
    out = res.getOutputStream();
    out.write(bytes, 0, bytes.length);
} catch (Exception e) {
    e.printStackTrace();
} finally {
    out.flush();
    out.close();
}

HTH

Answer 2

一些想法：

• 如果您使用二进制流（PDF 是二进制的），PrintWriter 将无法工作
• 如果客户端超时或断开连接，则可能会出现非法状态。该过程的数据包跟踪会告诉您很多信息（即使您不能很好地阅读它们）。查看 WireShark 或适用于您的平台的内容。值得您花时间至少了解一点有关线路级别发生的事情。
• 确保您从报告生成中返回的数据实际上是 pdf 文件。将其写入文件并尝试打开。
• 有些情况需要您在写入流之前设置 http 长度标头，否则当数据开始显示时它们会放弃。这里可能有必要。

Answer 3

代码具体是如何调用的呢？从堆栈跟踪来看，您正在使用以下命令运行 Java 类 handle 方法使用 小脚本 在 JSP 文件中（ inicio2.jsp 准确地说）。之后，Java 类将报告写入 OutputStream, ，JSP 文件将继续输出文件本身的剩余部分（包括空格！），这将隐式调用 getWriter() 将其写入响应。正是这会导致 IllegalStateException 正如你现在所面临的 getOutputStream() 之前已经在 J​​ava 类中调用过。

将 Java 代码放在 Java 类中固然很好，但这并不意味着您仍然可以使用 JSP 来调用它。JSP 不应包含任何一行 Java 代码。JSP 本身就是作为视图技术输出的一部分。要解决这一切，只需有一个 Struts 操作类（或 HttpServlet) 您可以通过 HTML 调用 <form> 或者 <a>.

Answer 4

自己的答案：

我已经把在道路实际连接到数据库，并得到了一些真实数据了JRXML和suddendly它的工作中，PDF在Mozilla打开，但异常持续发生。我不知道我怎么可以抛出和异常（我已经调试和异常发生在同一个地方），并能够看到的PDF。

所以我只能继续寻找真正发生在这里。我会用什么，我觉得（可能在星期一）回答。

感谢simonlord和吉姆·拉什对你有所帮助！ ：）

编辑：顺便说一下，这里是堆栈跟踪（这是一个在西班牙，如果需要的话我会翻译任何你不明白）： 再次编辑：好像我没有在15月 - 2010复制“1” ...可能大约从5月insetad一丝造成混乱。校正。

15-ene-2010 13:47:03 org.apache.catalina.core.ApplicationDispatcher invoke
GRAVE: El Servlet.service() para servlet jsp lanzó una excepción
java.lang.IllegalStateException: getOutputStream() ya ha sido llamado para esta respuesta
    at org.apache.catalina.connector.Response.getWriter(Response.java:607)
    at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:196)
    at javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:112)
    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:171)
    at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:116)
    at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:76)
    at org.apache.jsp.pages.inicio2_jsp._jspService(inicio2_jsp.java:300)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:679)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:584)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:497)
    at org.apache.struts.chain.commands.servlet.PerformForward.handleAsInclude(PerformForward.java:141)
    at org.apache.struts.chain.commands.servlet.PerformForward.perform(PerformForward.java:92)
    at org.apache.struts.chain.commands.AbstractPerformForward.execute(AbstractPerformForward.java:54)
    at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Unknown Source)
15-ene-2010 13:47:03 org.apache.struts.chain.commands.AbstractExceptionHandler execute
ADVERTENCIA: Unhandled exception
org.apache.jasper.JasperException: getOutputStream() ya ha sido llamado para esta respuesta
    at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:460)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:367)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:679)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:584)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:497)
    at org.apache.struts.chain.commands.servlet.PerformForward.handleAsInclude(PerformForward.java:141)
    at org.apache.struts.chain.commands.servlet.PerformForward.perform(PerformForward.java:92)
    at org.apache.struts.chain.commands.AbstractPerformForward.execute(AbstractPerformForward.java:54)
    at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Unknown Source)
15-ene-2010 13:47:03 org.apache.struts.chain.commands.ExceptionCatcher postprocess
ADVERTENCIA: Exception from exceptionCommand 'servlet-exception'
org.apache.jasper.JasperException: getOutputStream() ya ha sido llamado para esta respuesta
    at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:460)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:367)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:679)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:584)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:497)
    at org.apache.struts.chain.commands.servlet.PerformForward.handleAsInclude(PerformForward.java:141)
    at org.apache.struts.chain.commands.servlet.PerformForward.perform(PerformForward.java:92)
    at org.apache.struts.chain.commands.AbstractPerformForward.execute(AbstractPerformForward.java:54)
    at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Unknown Source)
15-ene-2010 13:47:03 org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: Servlet.service() para servlet action lanzó excepción
java.lang.IllegalStateException: getOutputStream() ya ha sido llamado para esta respuesta
    at org.apache.catalina.connector.Response.getWriter(Response.java:607)
    at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:196)
    at javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:112)
    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:171)
    at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:116)
    at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:76)
    at org.apache.jsp.pages.inicio2_jsp._jspService(inicio2_jsp.java:300)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:679)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:584)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:497)
    at org.apache.struts.chain.commands.servlet.PerformForward.handleAsInclude(PerformForward.java:141)
    at org.apache.struts.chain.commands.servlet.PerformForward.perform(PerformForward.java:92)
    at org.apache.struts.chain.commands.AbstractPerformForward.execute(AbstractPerformForward.java:54)
    at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
    at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Unknown Source)