Download file from server to local

[xiao wang <xd...@googlemail.com>]

Hi there,

I am writing JSF portlet using myFaces. The JSF portlet will download a file
to local from server and the file in the server side will be deleted after
downloaded. The code works fine as a web application. But it can not work
properly as portlet.

In a jsp page, a button is displayed to invoke the downloadFile method.
 <h:commandButton value="downLoad" action="#{myFile.downloadFile}" />. When
running  my JSF code as web application,  to click the "downLoad" button, a
window will popup to display "open" or "save" the file. But if running as
JSF portlet, when click the "downLoad" button, no window pops up. But
the file in the server side does be deleted after the button is clicked.

any idea?

Thanks a lot in advance.

Below is the method to download file from server:

    public void downloadFile(){
        javax.faces.context.FacesContext conText =
javax.faces.context.FacesContext.getCurrentInstance();
        javax.servlet.http.HttpServletResponse response = (
javax.servlet.http.HttpServletResponse
)conText.getExternalContext().getResponse();

        String path = System.getProperty("java.io.tmpdir");
        filename = "test.ppt";
        File file = null;
        try {
            String _fileString = path + File.separator + filename;
            file = new File(_fileString);
            java.io.FileInputStream fis = new java.io.FileInputStream(file);

            String contenttype = "application/octet-stream";
            response.setContentType(contenttype);
            response.setHeader("Content-Disposition", "attachment;
filename=" + filename + ";");
            javax.servlet.ServletOutputStream out = response.getOutputStream
();
            int c = 0;
            while ((c=fis.read())!=-1) {
                out.write(c);
            }
            out.flush();
            out.close();
            file.delete();
        } catch (Exception e) {
            if (file!=null && file.exists()) {
                file.delete();
                System.out.println("[srb] file deleted on web server");
            }
            return;
        }

       conText.getApplication
().getStateManager().saveSerializedView(conText);
       conText.responseComplete();
    }

Re: Download file from server to local

[Scott O'Bryan <da...@gmail.com>]

Xaio,

Yes, this won't work in a portal environment.  Your "file" needs to be a 
resource that you retrieve and, as such, the url to your file needs to 
be encoded as a resource url.  Nuisances aside, consider a "normal" 
portal usecase where an "action" will cause all portlets on the screen 
to resubmit.  This means that the Portal needs to return all of it's 
data, including data for itself and all the other portlets, to the 
screen at the same time.  The Portal, therefore, has to force the 
content type to be something compatible with itself and all portlets.

My suggestion would be to create a servlet which deletes the file for 
you and sends the resource back with the correct content type.  You 
would then encode the url to this servlet as a resource url and use 
something like a goLink to access it.

Also note that some renderkits will do the encoding for you, so you 
should make sure that you use the correct component to reference this 
servlet.  I know the Trinidad goLink encodes url's as a resource url.  
I'm not sure about the other renderkits.

Scott

xiao wang wrote:
> Hi there,
>  
> I am writing JSF portlet using myFaces. The JSF portlet will download 
> a file to local from server and the file in the server side will be 
> deleted after downloaded. The code works fine as a web application. 
> But it can not work properly as portlet.  
>  
> In a jsp page, a button is displayed to invoke the downloadFile 
> method.  <h:commandButton value="downLoad" 
> action="#{myFile.downloadFile}" />. When running  my JSF code as web 
> application,  to click the "downLoad" button, a window will popup to 
> display "open" or "save" the file. But if running as JSF portlet, when 
> click the "downLoad" button, no window pops up. But the file in the 
> server side does be deleted after the button is clicked. 
>  
> any idea?
>  
> Thanks a lot in advance.
>  
> Below is the method to download file from server: 
>
>     public void downloadFile(){
>         javax.faces.context.FacesContext conText = 
> javax.faces.context.FacesContext.getCurrentInstance();
>         javax.servlet.http.HttpServletResponse response = 
> (javax.servlet.http.HttpServletResponse 
> )conText.getExternalContext().getResponse();
>
>         String path = System.getProperty("java.io.tmpdir");
>         filename = "test.ppt";
>         File file = null;
>         try {
>             String _fileString = path + File.separator + filename;
>             file = new File(_fileString);
>             java.io.FileInputStream fis = new 
> java.io.FileInputStream(file);
>            
>             String contenttype = "application/octet-stream";       
>             response.setContentType(contenttype);
>             response.setHeader("Content-Disposition", "attachment; 
> filename=" + filename + ";");
>             javax.servlet.ServletOutputStream out = 
> response.getOutputStream();
>             int c = 0;
>             while ((c=fis.read())!=-1) {
>                 out.write(c);
>             }
>             out.flush();
>             out.close();
>             file.delete();
>         } catch (Exception e) {
>             if (file!=null && file.exists()) {
>                 file.delete();
>                 System.out.println("[srb] file deleted on web server");
>             }
>             return;
>         }
>                 
>        
> conText.getApplication().getStateManager().saveSerializedView(conText); 
>        conText.responseComplete();
>     }
>