getOutputStream() has already been called for this response

Question

I google the error message getOutputStream() has already been called for this response and many people said it is because of the space or newline after <% or %>, but in my code , there is no a space or a newline. I am using tomcat6 on linux.

<%@     page import="java.servlet.*,     javax.servlet.http.*,     java.io.*,     java.util.*,     com.lowagie.text.pdf.*,     com.lowagie.text.*"     %><%     response.setContentType("application/pdf");     Document document = new Document();     try{         ByteArrayOutputStream buffer = new ByteArrayOutputStream();         PdfWriter.getInstance(document, buffer);         document.open();         PdfPTable table = new PdfPTable(2);         table.addCell("1");         table.addCell("2");         table.addCell("3");         table.addCell("4");         table.addCell("5");         table.addCell("6");         document.add(table);         document.close();         DataOutput dataOutput = new DataOutputStream(response.getOutputStream());         byte[] bytes = buffer.toByteArray();         response.setContentLength(bytes.length);         for(int i = 0; i < bytes.length; i++)         {         dataOutput.writeByte(bytes[i]);         }     }catch(DocumentException e){         e.printStackTrace();     }  %> 

~

org.apache.jasper.JasperException: java.lang.IllegalStateException: getOutputStream() has already been called for this response     org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:410)     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)     javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 

root cause

java.lang.IllegalStateException: getOutputStream() has already been called for this response     org.apache.catalina.connector.Response.getWriter(Response.java:610)     org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:198)     org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125)     org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118)     org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:188)     org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:118)     org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:77)     org.apache.jsp.Account.Domain.testPDF_jsp._jspService(testPDF_jsp.java:94)     org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)     javax.servlet.http.HttpServlet.service(HttpServlet.java:717)     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)     javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 

Answer 1

Ok, you should be using a servlet not a JSP but if you really need to... add this directive at the top of your page:

<%@ page trimDirectiveWhitespaces="true" %> 

Or in the jsp-config section your web.xml

<jsp-config>   <jsp-property-group>     <url-pattern>*.jsp</url-pattern>     <trim-directive-whitespaces>true</trim-directive-whitespaces>   </jsp-property-group> </jsp-config> 

Also flush/close the OutputStream and return when done.

dataOutput.flush(); dataOutput.close(); return;