JSF 2.0 Convert XHTML Page to PDF using Flying Saucer: java.lang.IllegalStateException

Question

I am trying to convert and export a JSF Page to PDF. I tried it the following way:

Bean:

public void createPDF() {
    try {
        ITextRenderer renderer = new ITextRenderer();
        renderer.setDocument(new URL(url).toString());
        renderer.layout();
        HttpServletResponse response = (HttpServletResponse) externalContext.getResponse();
        response.reset();
        response.setContentType("application/pdf");
        response.setHeader("Content-Disposition", "inline; filename=\"" +PDF_FILE_NAME+ "\"");
        OutputStream browserStream = response.getOutputStream();
        renderer.createPDF(browserStream);
    } catch (Exception ex) {
        Logger.getLogger(PdfBean.class.getName()).log(Level.SEVERE, null, ex);
    }
}

Page with the Create PDF Button /home.xhtml:

<ui:define name="content">
    <center>
        <h:form id="pdfgen">
            <h:panelGrid columns="2">
                <h:outputText value="Enter Name:"/>
                <h:inputText value="#{pdfBean.name}"/>
            </h:panelGrid>
            <h:commandButton value="Create PDF" action="#{pdfBean.createPDF()}"/>
        </h:form>
    </center>
</ui:define>

The Page which I want to convert:

<ui:define name="content">
    <center>
        <h:outputText value="Hello #{pdfBean.name}"/>
    </center>
</ui:define>

When I try that I get a PDF only once, then never again. I got following Facelet Exception:

SEVERE: Error Rendering View[/home.xhtml]
java.lang.IllegalStateException: PWC3991: getOutputStream() has already been called for this response
...
WARNING: StandardWrapperValve[Faces Servlet]: PWC1406: Servlet.service() for servlet Faces Servlet threw exception
java.lang.IllegalStateException: PWC3991: getOutputStream() has already been called for this response

What am I doing wrong?

Updated Bean: see BalusC's answer:

public void createPDF() {
    FacesContext facesContext = FacesContext.getCurrentInstance();
    ExternalContext externalContext = facesContext.getExternalContext();
    String servername = externalContext.getRequestServerName();
    String port = String.valueOf(externalContext.getRequestServerPort());
    String appname = externalContext.getRequestContextPath();
    String protocol = externalContext.getRequestScheme();
    this.url = protocol + "://" + servername + ":" + port + appname + PDF_PAGE;
    try {
        ITextRenderer renderer = new ITextRenderer();
        renderer.setDocument(new URL(url).toString());
        renderer.layout();
        HttpServletResponse response = (HttpServletResponse) externalContext.getResponse();
        response.reset();
        response.setContentType("application/pdf");
        response.setHeader("Content-Disposition", "inline; filename=\"" + PDF_FILE_NAME + "\"");
        OutputStream browserStream = response.getOutputStream();
        renderer.createPDF(browserStream);

    } catch (Exception ex) {
        Logger.getLogger(PdfBean.class.getName()).log(Level.SEVERE, null, ex);
    }
    facesContext.responseComplete();
}

Answer 1

You need to instruct JSF that you've already taken the response handling in your hands and that JSF should not handle the default navigation when the action method is finished. Add this to the end of the action method:

facesContext.responseComplete();

---

Update as per the comments, you're accessing ExternalContext as an instance variable which suggests that you assigned it and the FacesContext as class variable, either static or as property of a session scoped bean. This is definitely a bad idea. You should get hand of them inside the local method by FacesContext#getCurrentInstance() and never assign them as class variable. They are namely bound to a specific request thread which do not exist in next request anymore.