Bit #19 - Downloading a file

Use an af:fileDownloadActionListener Rich Faces component to download data from the server to a client machine. Add the listener inside the component that will initiate the download, an af:commandButton for example, and specify the content type and the name of the file. Also specify a method in a backing bean that will be called to perform the download. In the backing bean method get the formated data to be saved from the model and use the supplied OutputStream to write the data.


Example:

In .jsf page:

<af:commandbutton id="buttonid"  " text="Download" ...
    <af:filedownloadactionlistener contenttype="application/octet-stream"
                method="#{backingBean.doDownload}"  filename="defaultFilename.txt"/>          
</af:commandButton>

In backing bean:

  public void doDownload(FacesContext facesContext, OutputStream outputStream) {
      // write the neccessary code to get the download data from the Model
      String data = getDownloadData();

      // save to the output stream
      try {
          OutputStreamWriter writer = new OutputStreamWriter(outputStream,"UTF-8");
           writer.write(data);
           writer.close();
          outputStream.close();
      } catch (IOException e) {
          // handle I/O exceptions
      }
  }


Context:

JSF Page
Backing Bean