使用Java，PrimeFaces和jsf的ContentFlow使用情況

Question

我正在使用ContentFlow（http://www.jacksasylum.eu/ContentFlow/index.php）使用Java，PrimeFaces和jsf顯示來自數據庫的圖像。 我正在使用圖像servlet來幫助渲染圖像字節數組。

在使用圖像列表進行初始頁面加載時，此操作成功完成，但是在圖像列表更改后（使用數據表過濾器的結果）之后，我找不到使用新圖像列表重新加載/刷新ContentFlow的方法。

這種刷新在沒有實現ContentFlow的情況下可以成功進行，但是它似乎是在Javascript幕后做了一些事情來破壞了這一點，或者它與圖像servlet的配合不佳（有時會收到IllegalStateException）。 我在找任何人提供幫助方面遇到很多麻煩。

這是我的堆棧跟蹤...

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]

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.
            }
        }
    }
}

可以在http://www.jacksasylum.eu/ContentFlow/download.php上查看用於創建ContentFlow的ContentFlow Javascript文件。

獲得數據表選擇列表后，此xhtml代碼將起作用。 此外，嘗試使用過濾的數據表過濾的結果列表。 該ContentFlow的div沒有在這里實現...

<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>

用ContentFlow div封裝后，這xhtml代碼不起作用。 幕后一定發生了一些我不了解的事情...

<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>

Answer 1

我自己想通了。 創建了一個自定義Javascript函數，該函數成功刷新了ContentFlow。