问题
I'm currently using a third party image coverflow (http://www.jacksasylum.eu/ContentFlow/) to display images which are being saved within a database. I'm using Java, JPA, and Richfaces for this. I have set up an image servlet to handle the image display. I have a Richfaces datatable set up and I only want to display images of selected records within the coverflow. This functionality is in place to do this. I have a command button to render the image coverflow within an OutputPanel. My images display correctly down the page without errors before implementing the coverflow. So, I know my underlying functionality works as desired. The issue is that when I implement the coverflow by placing specific div tags around my img tags as instructed I get the following error:
Error Rendering View[/index.xhtml]: java.lang.IllegalStateException: Cannot create a session after the response has been committed
at org.apache.catalina.connector.Request.doGetSession(Request.java:2636) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.connector.Request.getSession(Request.java:2375) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:841) [jbossweb-7.0.10.Final.jar:]
at com.sun.faces.context.ExternalContextImpl.getSession(ExternalContextImpl.java:155) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at javax.faces.context.ExternalContextWrapper.getSession(ExternalContextWrapper.java:396) [jboss-jsf-api_2.1_spec-2.0.0.Final.jar:2.0.0.Final]
at com.sun.faces.renderkit.ServerSideStateHelper.writeState(ServerSideStateHelper.java:175) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at com.sun.faces.renderkit.ResponseStateManagerImpl.writeState(ResponseStateManagerImpl.java:122) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at com.sun.faces.application.StateManagerImpl.writeState(StateManagerImpl.java:166) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at com.sun.faces.application.view.WriteBehindStateWriter.flushToWriter(WriteBehindStateWriter.java:225) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:419) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:288) [jboss-jsf-api_2.1_spec-2.0.0.Final.jar:2.0.0.Final]
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:288) [jboss-jsf-api_2.1_spec-2.0.0.Final.jar:2.0.0.Final]
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139) [jsf-impl-2.1.5-jbossorg-1.jar:2.1.5-SNAPSHOT]
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594) [jboss-jsf-api_2.1_spec-2.0.0.Final.jar:2.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.10.Final.jar:]
at org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:62) [weld-core-1.1.5.AS71.Final.jar:2012-02-10 15:31]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:280) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.10.Final.jar:]
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.0.Final.jar:7.1.0.Final]
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:154) [jboss-as-web-7.1.0.Final.jar:7.1.0.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.10.Final.jar:]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.10.Final.jar:]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.10.Final.jar:]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.10.Final.jar:]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.10.Final.jar:]
at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_32]
Here is some of my code:
ImgServlet.java
/**
* Servlet implementation class ImgServlet
*/
@WebServlet(name = "ImgServlet", urlPatterns = {"/ImgServlet/*"})
public class ImgServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Inject
Screenshot model;
@PersistenceUnit(unitName = "primary")
private EntityManagerFactory emf;
public ImgServlet() {
super();
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
PrintWriter writer = response.getWriter();
ServletContext sc = getServletContext();
String classString = "Screenshot";
String idString = request.getParameter("id");
if (classString == null || classString.isEmpty() || idString == null || idString.isEmpty()) {
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
return;
}
Long id = Long.parseLong(idString.trim());
PhotoInterface entry = null;
EntityManager em = null;
try {
em = emf.createEntityManager();
} catch (Throwable e1) {
e1.printStackTrace();
}
try {
entry = em.find(Screenshot.class, id);
} catch (Exception ex) {
//Log.log(ex.getMessage());
}
if (entry == null) {
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
return;
}
ServletOutputStream out = null;
try {
response.reset();
// It works ok without setting any of these...
//response.setContentType(image.getContentType());
//response.setHeader("Content-Length", String.valueOf(image.getLength()));
//response.setHeader("Content-Disposition", "inline; filename=\"" + image.getName() + "\"");
response.setContentType("image/png");
out = response.getOutputStream();
if (entry.getPng() != null && entry.getPng().length != 0) {
out.write(entry.getPng());
getServletContext().log("Found png!!");
}
else
getServletContext().log("png is NULL!!!");
} catch (IOException e) {
getServletContext().log("Error finding png!!!");
} finally {
close(out);
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
private static void close(Closeable resource) {
if (resource != null) {
try {
resource.close();
} catch (IOException e) {
// Do your thing with the exception. Print it, log it or mail it.
}
}
}
}
contentflow_src.js - javascript used to render the coverflow and an example can be viewed at
http://www.jacksasylum.eu/ContentFlow/download.php
This currently works in my xhtml (without ContentFlow Div tags inside the outputPanel):
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:p="http://primefaces.org/ui">
<ui:composition
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:a4j="http://richfaces.org/a4j"
xmlns:rich="http://richfaces.org/rich"
xmlns:my="http://java.sun.com/jsf/composite/components"
xmlns:s="http://jboss.com/products/seam/taglib"
>
<h:head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<h:outputStylesheet name="screen.css" library="css"/>
<script language="JavaScript" type="text/javascript" src="contentflow_src.js" load="slideshow lightbox">
</script>
</h:head>
<h:body>
<h:form id="form">
<p:dataTable var="scrshot">
....................
....................
</p:dataTable>
<p:commandButton id="viewDetails" value="View Selected Screenshots" icon="ui-icon-search"
update=":form:imgBlock"/>
<p:outputPanel id="imgBlock" layout="block">
<a4j:repeat var="img" value="#{screenshotListProducer.selectedScreenshots}">
<img src="ImgServlet?id=#{img.id}" title="#{img.time}"/>
</a4j:repeat>
</p:outputPanel>
</h:form>
</h:body>
</ui:composition>
</html>
This doesn't work in my xhtml (after implementing the ContentFlow by wrapping with the Div tags inside the outputPanel) and triggers the error:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:p="http://primefaces.org/ui">
<ui:composition
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:a4j="http://richfaces.org/a4j"
xmlns:rich="http://richfaces.org/rich"
xmlns:my="http://java.sun.com/jsf/composite/components"
xmlns:s="http://jboss.com/products/seam/taglib"
>
<h:head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<h:outputStylesheet name="screen.css" library="css"/>
<script language="JavaScript" type="text/javascript" src="contentflow_src.js" load="slideshow lightbox">
</script>
</h:head>
<h:body>
<h:form id="form">
<p:dataTable var="scrshot">
....................
....................
</p:dataTable>
<p:commandButton id="viewDetails" value="View Selected Screenshots" icon="ui-icon-search"
update=":form:imgBlock"/>
<p:outputPanel id="imgBlock" layout="block">
<div class="ContentFlow" id="ContentFlow">
<div class="flow">
<a4j:repeat var="img" value="#{screenshotListProducer.selectedScreenshots}">
<div class="item">
<img src="ImgServlet?id=#{img.id}" title="#{img.time}"/>
</div>
</a4j:repeat>
</div>
</div>
</p:outputPanel>
</h:form>
</h:body>
</ui:composition>
</html>
Sorry about all of the code. If anyone can help it will be greatly appreciated! I've gone in circles for days trying to get the ContentFlow to play nice with my session.
来源：https://stackoverflow.com/questions/11660247/display-db-images-using-contentflow-coverflow-illegalstateexception-error