Download a file using getOutputStream() and bug when rendering the view that calls getWriter()()

Question

I am currently stuck, I need to download a file in a web page, it works, but I always get an exception.

I use getOutputStream() because I think that i cannot use getWriter() to write in a byte array. I am still not very sure about closing or not the outputstream, I have seen a lot of different opinions about it.

public void downloadFile() {
    int statementNumber = Integer.parseInt(
            FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("statementNumber"));
    MerchantStatementDocument document = findDocumentFromStatementNumber(statementNumber);
    HttpServletResponse response = (HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext()
            .getResponse();

    response.setHeader("Content-Disposition", "attachment;filename=" + document.getDocumentName());
    response.setContentType("application/pdf");
    ServletOutputStream out = null;
    try {
        out = response.getOutputStream();
        out.write(document.getDocument());
        out.flush();
        FacesContext.getCurrentInstance().getResponseComplete();
        FacesContext.getCurrentInstance().renderResponse();
    } catch (IOException err) {
        err.printStackTrace();
    } finally {
        try {
            if (out != null) {
                out.close();
            }
        } catch (IOException err) {
            err.printStackTrace();
        }
    }
}

This works, and perfectly. But I get an exception on my stack trace, and I would like to avoid having exception, because this isn't good behaviour. My exception is this :

2015-12-11T13:08:03.149+1100|Severe: Error Rendering View[/pages/private/merchant_statement/manageMerchantsDocuments.xhtml]
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:777)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:224)
at com.sun.faces.context.ExternalContextImpl.getResponseOutputWriter(ExternalContextImpl.java:846)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.createResponseWriter(FaceletViewHandlingStrategy.java:1192)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:403)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:133)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
at java.lang.Thread.run(Thread.java:744)

It is because somewhere in javax.faces.jar it calls the method getWriter(), which I cannot use because I used getOutputStream.

And I am not sure about what I should do.

Is there a way to download a file using getWriter() instead of using getOutputStream()? And why does it need to render the view if I am staying on the same page? Is there a way to avoid my program to throw this exception?

Any help would be appreciated, thanks !

Remove this line : `FacesContext.getCurrentInstance().renderResponse();` and insist upon obtaining the `OutputStream` from `ExternalContext#getResponseOutputStream();` while using JSF. — Tiny, Dec 11 '15 at 03:35
Thanks a lot for your comment, it put me on track to find the solution ! — IPierrot, Dec 11 '15 at 04:08

score 0 · Answer 1 · edited May 23 '17 at 11:44

I found the solution of my problem, thanks to another post on stackoverflow I haven't seen before.

How to provide a file download from a JSF backing bean?

The problem was that I didn't put facesContext.responseComplete() at the end of my code. It now looks like that :

    ExternalContext ec = FacesContext.getCurrentInstance().getExternalContext();
    int statementNumber = Integer.parseInt(ec.getRequestParameterMap().get("statementNumber"));
    MerchantStatementDocument document = findDocumentFromStatementNumber(statementNumber);
    HttpServletResponse response = (HttpServletResponse) ec.getResponse();

    response.setHeader("Content-Disposition", "attachment;filename=" + document.getDocumentName());
    response.setContentType("application/pdf");
    OutputStream out = null;
    try {
        out = ec.getResponseOutputStream();
        out.write(document.getDocument());
        out.flush();
        FacesContext.getCurrentInstance().responseComplete();
    } catch (IOException err) {
        err.printStackTrace();
    }

It now works like a charm !

Download a file using getOutputStream() and bug when rendering the view that calls getWriter()()

1 Answers1