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Editorial Team
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Asked: 2026-06-17T16:11:40+00:00

I’m trying to show inline PDF which is opened in new browser window. I

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I’m trying to show inline PDF which is opened in new browser window. I have following scenario:

  1. In some ActionListen which is called by ajax I generate PDF content, put data in session, and send Javascript to be executed (window.open to open new page to show PDF)

  2. On opened page I just have p:media tag inside h:body with value pointing to StreamedContent:

Now, on that page my PDF is not generated. In log I can see these two lines:

org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. Expression cannot be null

I started to debug and find out a few things.

First, I added breakpoint to @PostConstruct method of my RequestScoped bean. What is interesting is that breakpoint is reached twice, and to my big surprise after that PDF is shown perfectly?!

After some debugging through PrimeResourceHandler I figure out that in some cases ValueExpression is not calculated, in fact it throws NullPointerException, and again while debugging I saw that two requests are sent, and second request fails because dynamicContentId is removed in first request, and second call to handleResourceRequest doesn’t have sense.

Through Firebug I can see two requests, first which is good with PDF data, and second which is also with content-type application/pdf but empty, with size 0.

xhtml page:

<html>
  <h:head></h:head>
  <h:body>
    <p:media value="#{reportBean.streamedContent}" player="pdf" width="500" height="500"/>
  </h:body>
</html>

backing bean:

@RequestScoped
public class StampaListeBackingBean implements Serializable {

    private static final long serialVersionUID = 1L;

    private StreamedContent streamedContent;

    @PostConstruct
    public void init() {
        Map<String, Object> session = FacesContext.getCurrentInstance().getExternalContext().getSessionMap();
        byte[] b = (byte[]) session.get("reportBytes");
        if (b != null) {
            streamedContent = new DefaultStreamedContent(new ByteArrayInputStream(b), "application/pdf");
        }
    }

    public StreamedContent getStreamedContent() {
        if (FacesContext.getCurrentInstance().getRenderResponse()) {
            return new DefaultStreamedContent();
        } else {
            return streamedContent;
        }
}

    public void setStreamedContent(StreamedContent streamedContent) {
        this.streamedContent = streamedContent;
    }
}

I need to understand why two requests are sent on page with p:media tag, and to figure out how to make this work. Backing bean is request scoped, it creates StreamedContent in @PostConstruct method, and has getter and setter for that field. Primefaces version is 3.4.2, with Mojarra 2.1.14.

ADDED:

It is easy to reproduce my problem. If code in init method is replaced with following:

FileInputStream fis = new FileInputStream(new File("C:\\samplexxx.pdf"));
streamedContent = new DefaultStreamedContent(fis, "application/pdf");

problem can be reproduced.

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1 Answer

  1. Editorial Team

    I can reproduce your problem. It indeed doesn’t work in Firefox (nor in IE9, but it works in Chrome). PrimeFaces lead Cagatay has also mentioned that several times.

    I’m not sure if this is a bug in the PrimeFaces resource handler or in the browser. I’ll leave it in the middle.

    In the meanwhile, your best bet is a simple web servlet for the job. Just create this class:

    @WebServlet("/report.pdf")
public class PdfReportServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        byte[] content = (byte[]) request.getSession().getAttribute("reportBytes");
        response.setContentType("application/pdf");
        response.setContentLength(content.length);
        response.getOutputStream().write(content);
    }

}

    And invoke it as follows:

    <p:media value="/report.pdf" ... />

    That’s it. No XML config necessary. It works for me in all browsers. Depending on the functional requirements, you may want to further finetune response headers related to browser caching.

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