Setter of application scoped bean fails to set value

Question

I'm making page using Primefaces with form with ability to ajax-upload image and preview it before submitting whole form.

To achieve this I made dialog outside main form:

<p:dialog id="imageDlg" header="Load Image" modal="true"
          widgetVar="imageUploadWidget">
  <h:form id="imageForm" enctype="multipart/form-data">      
    <p:fileUpload mode="advanced" auto="true" sizeLimit="9999999" 
                  allowTypes="/(\.|\/)(gif|jpe?g|png)$/"
                  fileUploadListener="#{pageBean.imageUploadHandler}">
    </p:fileUpload>
  </h:form>    
</p:dialog>

Inside main form there is p:graphicImage component to display just uploaded image and button to show dialog. Page is backed by view scoped bean (PageBean), but to pass StreamedContent to p:graphicImage value bean should be session or application scoped (because method called multiply times). So I made second application scoped bean (ImageBean) only for this purpose.

<p:graphicImage value="#{imageBean.imageStreamedContent()}"/>
<p:commandButton value="Choose image" type="button" 
                 onclick="imageUploadWidget.show();"/>

Code of ImageBean:

@ApplicationScoped
@ManagedBean
public class ImagesBean implements Serializable {

private byte[] image;
//getter & setter

  public StreamedContent imageStreamedContent() {
      FacesContext context = FacesContext.getCurrentInstance();
      if (context.getCurrentPhaseId() == PhaseId.RENDER_RESPONSE) {
          return new DefaultStreamedContent();
      } else {
          return new DefaultStreamedContent(new ByteArrayInputStream(getImage()));
      }
  }
}

The next part is fileUploadListener. Idea is simple — set corresponding fields of PageBean (to save it later on form submit) of ImageBean (to show it after partial refresh) and update part of main form:

@ManagedBean
@ViewScoped
public class PageBean implements Serializable {

@ManagedProperty(value="#{imageBean}")
ImagesBean imagesBean;
...

public void imageUploadHandler(FileUploadEvent event) {
    getImagesBean().setImage(event.getFile().getContents());
    RequestContext.getCurrentInstance().update("form:tabPanel1");
}

Here comes strange thing. Inside setImage() method everything is OK - field is set, getter works fine. But then page refresh, imageBean.getImage() inside imageBean.imageStreamedContent() returns null.

More accurate — it returns old value, as if setter was never called or was called on another instance of bean. I checked it on another String field: initialized it in ImageBean constructor, in handler invoked setter with another value and refreshed part of main form. Same thing: old value from constructor.

I think, that I'm missing something about bean life cycle or scope specific. Or maybe there is less complicated way to implement this task?

Answer 1

There is a problem with using StreamedContent in Primefaces for p:graphicImage and p:media.
You can see Cagatay Civici 's comments on this topic in Primefaces forum here.

In my experience, when I had the slimier(more or less) problem This and This answers by BalusC helped me.

I used a saperate Servlet instead of Managedbean to stream the dynamic content to p:media (in mycase).

Here is my code for your reference(if you need any):

PreviewFileServlet.java

@WebServlet("/PreviewFile")
public class PreviewFileServlet extends HttpServlet {

   public PreviewFileServlet() {
    super();
   }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext context = request.getServletContext();
        String path = request.getParameter("PREVIEW_FILE_PATH");
        logger.info("Received pathe for Preview:"+path);
        try{
        if(null!=path){
            java.io.File f = new java.io.File(path);
            if(f.exists()){
            FileInputStream fin = new FileInputStream(f);
            byte b[] = new byte[(int)f.length()];
            fin.read(b);
            response.setContentLength(b.length);
            response.setContentType(context.getMimeType(path));
            response.getOutputStream().write(b);
            response.getOutputStream().close();
            logger.info("File sent successfully for Preview.");
            }
            else{
                logger.warn("File sepecified by path:-"+path+"-:, NOT found");
            }
        }
        }catch(Exception e){

        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

Facelet Code

<p:media value="/PreviewFile?PREVIEW_FILE_PATH=#{fileManager.previewFilePath}" />

Hope this helps. And there are lot of questions on this topic of StreamedContent in stackoverflow itself, go through them once.