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Date: Tue, 03 Jul 2007 11:46:03 +0200
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To: Tomcat Users List <users@tomcat.apache.org>
Subject: Re: Images and response.getOutputStream()
References: <28174dd80707030236o5370101bx5325253f0d160980@mail.gmail.com>
In-Reply-To: <28174dd80707030236o5370101bx5325253f0d160980@mail.gmail.com>
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Hi Lyallex!
You're getting a OutputStream ftrom a JSP? If the JSP has a simple 
single empty line before your java code <%%>, the JSP framework  get a 
writer before your java code is executred. This is the cause of the 
IllegalState Exception. The rigth way to do this is from a servlet, but 
if you prefer still using JSP, clean any empty space before your java code.

This code probably fails:

   <%@page import ..>
   <%@page ... >
  
   <%
   //my java code
   %>
  
   EOF

An this avoid the problem:

   <%page ....><%
   //my java code
   //other java line
   %>EOF

Best regards.
Ricardo

Lyallex escribi�:
> Hi
>
> I'm not sure this is a Tomcat question, more likely a poor 
> understanding of
> the Request/Response lifecycle on my part but I'll give it a go anyway.
>
> After agonising for days(weeks) over whether to store my images in a
> database or on the filesystem I opted for the database.
>
> I have everything working fine ... apart from one little niggling 
> thing that
> I just cannot figure out.
>
> Every time I get an image from the database I get an exception
>
> java.lang.IllegalStateException: getOutputStream() has already been 
> called
> for this response ...
>
> Now I think I understand why this is happening, I read somewhere that you
> cannot get a JspWriter (via a call to the implicit object out for 
> example)
> and a binary output stream
> (ServletOutputStream outStream = response.getOutputStream ()) from the 
> same
> response. Nothing falls over and the images appear fine. It's really the
> exception traces I'm trying to get rid of
>
> It appears that others are also using a database to store images and have
> things working.
> (mainly from http://marc.info/?l=tomcat-user)
>
> Can anyone advise me as to how to write both text and image data out 
> to the
> same response without this exception clogging up all my log files ?
>
> I have included code below if you want/need to read it
>
> Many thanks
> Duncan
>
>
> //============== get an image in a jsp =============
> //where p is a Product Object that contains information on the image 
> name as
> stored in the database
> //images can be thumbnails or normal size
>
> <img 
> src="imageproxy.jsp?imageid=<%=p.calculateImageId()%>&imagetype=thumb"
> width='80'>
>
> //============== imageproxy.jsp ================
> //where ImageServer is a singleton that gets an InputStream on a MySQL
> database BLOB
>
>        boolean DEBUG = false;
>
>        ServletOutputStream outStream = response.getOutputStream();
>
>        response.reset();
>        response.setHeader("Expires", "-1");
>        response.setHeader("Cache-Control", "no-cache");
>
>        String imageId = request.getParameter (imageid);
>        String imageType = request.getParameter(imagetype);
>
>        ImageServer images = ImageServer.getServer();
>        InputStream inStream = images.getImageData(imageId, imageType);
>
>        if(DEBUG){
>            System.out.println("imageproxy.jsp, inStream has " +
> inStream.available() + " bytes available");
>        }
>
>        byte[] bytes = new byte[1000];
>        int bytesRead = inStream.read(bytes);
>        while (bytesRead != -1) {
>            outStream.write(bytes,0,bytesRead);
>            bytesRead = inStream.read(bytes);
>        }
>        outStream.flush ();
>        inStream.close();
>
> //============= Just FYI here is the trace (one per image) =============
>
> SEVERE: Servlet.service() for servlet jsp threw exception
> java.lang.IllegalStateException: getOutputStream() has already been 
> called
> for this response
>        at org.apache.catalina.connector.Response.getWriter(Response.java
> :599)
>        at org.apache.catalina.connector.ResponseFacade.getWriter(
> ResponseFacade.java:195)
>        at org.apache.jasper.runtime.JspWriterImpl.initOut (
> JspWriterImpl.java:124)
>        at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(
> JspWriterImpl.java:117)
>        at org.apache.jasper.runtime.PageContextImpl.release(
> PageContextImpl.java:191)
>        at
> org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext (
> JspFactoryImpl.java:115)
>        at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(
> JspFactoryImpl.java:75)
>        at 
> org.apache.jsp.imageproxy_jsp._jspService(imageproxy_jsp.java:94)
>        at org.apache.jasper.runtime.HttpJspBase.service (HttpJspBase.java
> :97)
>        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
>        at org.apache.jasper.servlet.JspServletWrapper.service(
> JspServletWrapper.java:332)
>        at org.apache.jasper.servlet.JspServlet.serviceJspFile (
> JspServlet.java:314)
>        at 
> org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
>        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
>        at 
> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(
> ApplicationFilterChain.java:252)
>        at org.apache.catalina.core.ApplicationFilterChain.doFilter(
> ApplicationFilterChain.java:173)
>        at org.apache.catalina.core.StandardWrapperValve.invoke(
> StandardWrapperValve.java :213)
>        at org.apache.catalina.core.StandardContextValve.invoke(
> StandardContextValve.java:178)
>        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(
> AuthenticatorBase.java:432)
>        at org.apache.catalina.core.StandardHostValve.invoke (
> StandardHostValve.java:126)
>        at org.apache.catalina.valves.ErrorReportValve.invoke(
> ErrorReportValve.java:105)
>        at org.apache.catalina.core.StandardEngineValve.invoke(
> StandardEngineValve.java:107)
>        at org.apache.catalina.connector.CoyoteAdapter.service(
> CoyoteAdapter.java:148)
>        at org.apache.coyote.http11.Http11Processor.process(
> Http11Processor.java:869)
>        at
> org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection( 
>
> Http11BaseProtocol.java:664)
>        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(
> PoolTcpEndpoint.java:527)
>        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(
> LeaderFollowerWorkerThread.java :80)
>        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(
> ThreadPool.java:684)
>        at java.lang.Thread.run(Thread.java:595)
>


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