Question

我正在尝试从MySQL-DB下载pdf（我把它作为一个Blob，到目前为止一切正常。但是当我试图让ServletOutputstream将它发送到客户端的程序时崩溃。

AFAIK在以前调用方法或getwriter-method有方法时抛出异常。但是我根本没有在我的代码中使用getwriter方法，并且没有达到程序中的其他getOutPutStream方法（我将它们注释掉以确保）。
（如果因为任何原因重要，整个事情都发生在JSP中）

下面是我的代码片段和例外：

代码

Blob pdf = null;
if(request.getParameter("reportId") != null){
    pdf = testszenario.getReportErgebnisPdf(Integer.parseInt(request.getParameter("reportId")), request.getParameter("erzeugung"));
}
byte[] buf = new byte[(int)pdf.length()];
InputStream inputStream  = pdf.getBinaryStream();
inputStream.read(buf);
inputStream.close();
response.setContentType("application/pdf");
response.setHeader("Content-disposition","attachment; filename=test.pdf"); 

ServletOutputStream sos = response.getOutputStream();
// response.getOutputStream().write(buf);

异常

26.03.2013 09:28:29 org.apache.catalina.core.ApplicationDispatcher invoke
SCHWERWIEGEND: Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException
    at org.apache.jasper.runtime.ServletResponseWrapperInclude.getOutputStream(ServletResponseWrapperInclude.java:63)
    at org.apache.jsp.jsp.modules.Testszenario.PostReportResultOverview_jsp._jspService(PostReportResultOverview_jsp.java:115)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:630)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:535)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:472)
    at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
    at org.apache.jsp.jsp.McFrame_jsp._jspService(McFrame_jsp.java:284)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
    at java.lang.Thread.run(Thread.java:619)

Answer 1

请检查您的回复是否已提交。如果您尝试对已提交的响应执行某些操作，则可能会出现IllegalStateException。如果超过页面缓冲区大小，将提交响应。

Answer 2

在JSP中执行此操作可能确实很重要。请记住，JSP是Web应用程序请求的输出呈现阶段的一部分，因此容器可能已经获取了writer对象。尝试将代码移动到servlet中。它会让你更好地控制作家/流。

response.getOutputStream（）在第一次调用时抛出IllegalStateException

2 个答案: