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Display db images using ContentFlow (coverflow) IllegalStateException error

I currently use third-party image coverage (http://www.jacksasylum.eu/ContentFlow/) to display images that are stored in the database. For this I use Java, JPA and Richfaces. I installed an image servlet for image processing. I have a Richfaces dataset and I only want to display images of the selected records in the stream. This feature is designed for this. I have a command button to render an image stream within an OutputPanel. My images are displayed correctly on the page without errors before implementing coverage. So, I know that my basic functionality works as I wish. The problem is that when I implement coverage by placing certain div tags around my img tags according to the instructions, 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 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 is javascript used to render coverage, 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 does not work in my xhtml (after implementing ContentFlow by wrapping Div tags inside the OutputPanel) and causes an 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 for all the code. If anyone can help, he will be very grateful! I traveled around several times trying to get ContentFlow to play well with my session.

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Source: https://habr.com/ru/post/920647/

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