IllegalStateException problem on running jboss

[betamax]

Hi,everybody
I am using jboss 4.0.5 GA, it generates the following error when i tried to test a ckcodeimage.jsp:

14:20:15,796 ERROR [[jsp]] 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:182)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:115)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
at org.apache.jsp.jsp.ckcodeimage_jsp._jspService(ckcodeimage_jsp.java:133)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:334)
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:810)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
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.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.jboss.web.tomcat.tc5.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156)
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.Http11AprProcessor.process(Http11AprProcessor.java:833)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:639)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1285)
at java.lang.Thread.run(Thread.java:595)

ckcodeimage.jsp is the following:

<%@ page contentType="image/jpeg; charset=GBK" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc){//??????????
 Random random = new Random();
 if(fc>255) fc=255;
 if(bc>255) bc=255;
 int r=fc+random.nextInt(bc-fc);
 int g=fc+random.nextInt(bc-fc);
 int b=fc+random.nextInt(bc-fc);
 return new Color(r,g,b);
 }
%>
<%
//???????
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);

// ????????
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// ???????
Graphics g = image.getGraphics();

//?????
Random random = new Random();

// ?????
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);

//????
g.setFont(new Font("Times New Roman",Font.PLAIN,18));

//???
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);


// ????155???????????????????????
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
 int x = random.nextInt(width);
 int y = random.nextInt(height);
 int xl = random.nextInt(12);
 int yl = random.nextInt(12);
 g.drawLine(x,y,x+xl,y+yl);
}

// ?????????(4???)
//String rand = request.getParameter("rand");
//rand = rand.substring(0,rand.indexOf("."));
String sRand="";
for (int i=0;i<4;i++){
 String rand=String.valueOf(random.nextInt(10));
 sRand+=rand;
 // ??????????
 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//???????????????????????????????
 g.drawString(rand,13*i+6,16);
}

// ??????SESSION
session.setAttribute("rand",sRand);


// ????
g.dispose();

// ???????
ServletOutputStream output = response.getOutputStream();
ImageIO.write(image, "JPEG", output);

%>

[jwenting]

one more reason to NOT use scriptlets in JSPs.
All that code belongs in a servlet, NOT a JSP (in fact no Java code at all should be in JSPs).

What you're trying to do is extremely illegal. It will never work. The outputstream is after all private to the JSP and created implicitly when it's first started.
That's a consequence of what JSPs actually are, and how they're turned into Java code before being compiled.

Do your image generation in a servlet, there's no need ever to do this in a JSP.

[jwenting]

P.S. this has nothing to do with JBoss, it's servlet/JSP basics.