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POJSF file download NullPointerException with view Parameter
 

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  1. POJSF file download NullPointerException with view Parameter
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    <p>I hope I get this one straight:</p> <p>I try to create an <em>JSF 2.0</em> Page optimized for mobile use on <em>Tomcat 7</em>. Therefore I use <em>Mojarra 2.1.6</em> and <em>PrimeFaces</em> (Core 3.1.1 and Mobile 0.9.1).</p> <h3>My scenario:</h3> <ol> <li>User visits simplified URL, e.g. www.someurl.eu/view.xhtml/12345678</li> <li>ServletFilter rewrites Url to www.someurl.eu/view.xhtml?id=12345678</li> <li>Url Parameter gets provided to ManagedBean</li> <li>Necessery Data gets evaluated and published to my view.xhtml</li> <li>On my view.xhtml a button for download is provided</li> </ol> <h3>My problem:</h3> <p>By clicking the button the server shows me a NPE when the ManagedBean is set to @RequestScoped. My assumption is that by clicking the button a new request is fired, my URL-parameter gets lost and the download file is not available anymore. I don't know if I'm right but if so I don't know how to solve this one elegant.</p> <h3>My ManagedBean:</h3> <pre><code>@ManagedBean @RequestScoped public class ViewBean { // Elements ... private StreamedContent file; ... // Getter and Setter ... public StreamedContent getFile() { invalidateSession(); return file; } public void setFile(StreamedContent file) { this.file = file; } ... // Init @PostConstruct public void init() { //read URL-Parameter urlSdbac = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("id"); // validate if(urlSdbac == null || urlSdbac.equals("") || urlSdbac.length() != 8) { urlSdbac = "invalid"; } // get Data else { SdbCustomerData cd = getFileMetadata(urlSdbac); if(cd == null) { this.name = "invalid code"; this.language = "no language options found"; } else { ... // prepare File for Download this.file = new Helper().getWebDavFile(cd.getCid(), cd.getName()); } } } </code></pre> <h3>My view.xhtml:</h3> <pre><code>&lt;h:form&gt; &lt;pm:page title="Download"&gt; &lt;pm:view&gt; &lt;pm:content&gt; ... &lt;p:commandButton value="Download" ajax="false"&gt; &lt;p:fileDownload value="#{viewBean.file}" /&gt; &lt;/p:commandButton&gt; &lt;/pm:content&gt; &lt;/pm:view&gt; &lt;/pm:page&gt; &lt;/h:form&gt; </code></pre> <p></p> <h3>Last but not least, my Filter:</h3> <pre><code>@Override public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; String url = request.getRequestURI(); Pattern sdbac = Pattern.compile("[A-Za-z0-9]{8}"); Matcher fit = null; // check Page if(url.contains("view.xhtml/") &amp;&amp; (!url.contains("?id=") &amp;&amp; !url.endsWith("view.xhtml")) ) { String code = url.substring(url.indexOf("view.xhtml/")+11, url.length()); // validate Param? fit = sdbac.matcher(code); if(fit.matches()) { // redirect response.sendRedirect("/getSDS/view.xhtml?id=" + code); } else { // redirect response.sendRedirect("/getSDS/view.xhtml?id=invalid"); } } else { chain.doFilter(req,res); } } </code></pre> <p>My Filter is mapped to any URL <code>&lt;url-pattern&gt;/*&lt;/url-pattern&gt;</code></p> <p>I've also tried to set the ManagedBean to <em>@SessionScoped</em>. If I do so the download works fine but the user isn't able to change the URL because of the persitent data in the session scoped ManagedBean.</p> <p>Maybe I'm too blind to see the obvious solution.</p> <p>Any help would be appreciated! <strong>Thanks in advance!</strong></p> <p>P.S. The exception</p> <pre><code>java.lang.NullPointerException org.primefaces.component.filedownload.FileDownloadActionListener.processAction(FileDownloadActionListener.java:58) javax.faces.event.ActionEvent.processListener(ActionEvent.java:88) javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769) javax.faces.component.UICommand.broadcast(UICommand.java:300) javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259) com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:593) eu.qualisys.getsds.filter.SDBACParamFilter.doFilter(SDBACParamFilter.java:53) </code></pre>
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