Java – how to use GWT when downloading files using servlet?

I'm creating a simple project that allows me to upload and download files using GWT I can't download files from my server

For uploading files, I used http://code.google.com/p/gwtupload/ , then follow the instructions My files are stored in the website container outside the server (on the hard disk),

Now, when it comes to downloading files, I want the user to press a download button and any currently selected items will be downloaded I really don't know what to do

I know I need a servlet to download

public class DownloadAttachmentServlet extends HttpServlet {

@Override
protected void doPost(HttpServletRequest req,HttpServletResponse resp)
        throws ServletException,IOException {
    // TODO Auto-generated method stub
    super.doGet(req,resp);
}

@Override
protected void doGet(HttpServletRequest req,IOException {

    String fileName = (String) req.getSession().getAttribute("fileName");

    YFUser user = (YFUser) req.getSession().getAttribute(TestServiceImpl.SESSION_USER);
    if (user == null)
        throw new ServletException("Invalid Session");

    InputStream in = null;
    OutputStream out = resp.getOutputStream();

    FileInputStream fIn = new FileInputStream(fileName);
    byte[] buffer = new byte[4096];
    int length;
    while ((length = in.read(buffer)) > 0){
        out.write(buffer,length);
    }
    in.close();
    out.flush();

}
}

For now, I'll pass a filename string to retrieve the file for testing

Now that I've lost what to do on the client, I have a simple

public class DownloadFilePanel extends Composite {


public DownloadFilePanel(final YFUser user,final String fileName){

    final Element downloadIframe = RootPanel.get("__download").getElement();

    VerticalPanel content = new VerticalPanel();
    content.add(new Label("Download For this File : " + fileName));

    Button button = new Button("Download");
    button.addClickHandler(new ClickHandler(){
        @Override
        public void onClick(ClickEvent event) {
            // i do not kNow what to do here
    });
            content.add(button);
    initWidget(content);


}


}

The above is a simple widget that will provide a panel that allows you to download files based on filename

As mentioned above, I don't know what to do to download the file

Can anyone point me in the right direction?

Solution

On the client side, just create a regular < a href = "path / to / servlet" > tag If you want to create an anchor class dynamically, you can use the anchor class When the user clicks the link, the browser will automatically download the file