How can a user download a file in client side (Google Web Toolkit)

Question

I\'m using GWT(Google Web Toolkit) to make a website. I need to show a table to the user, and let the user download the contents of the table.

On the client side, h

Answer 1

If you know the path of the file, Code snippet is shown below.

button.addClickHandler(new ClickHandler()  
{ 

    @Overrid
    public void onClick(ClickEvent event) 
    {
        Window.open(GWT.getHostPageBaseURL() + "/file.rar", "name", "enabled");
    }
});

Answer 2

You REALLY need to distinguish between GWT client side java code and server side java code.

On the client side in your GWT Java Code

String url = GWT.getModuleBaseURL() + "downloadService?fileInfo1=" + fileInfo1;
Window.open( url, "_blank", "status=0,toolbar=0,menubar=0,location=0");

On server side in your non-gwt Java code-

In web.xml

<servlet>
    <servlet-name>downloadService</servlet-name>
    <servlet-class>AAA.BBB.CCC.DownloadServlet</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>downloadService</servlet-name>
    <url-pattern>/<gwtmodulename>/downloadService</url-pattern>
</servlet-mapping>

In server package code a servlet

    public class DownloadServlet extends HttpServlet{
    protected void doGet( HttpServletRequest req, HttpServletResponse resp ) throws ServletException, IOException
        {
            String fileName = req.getParameter( "fileInfo1" );

            int BUFFER = 1024 * 100;
            resp.setContentType( "application/octet-stream" );
            resp.setHeader( "Content-Disposition:", "attachment;filename=" + "\"" + fileName + "\"" );
            ServletOutputStream outputStream = resp.getOutputStream();
            resp.setContentLength( Long.valueOf( getfile(fileName).length() ).intValue() );
            resp.setBufferSize( BUFFER );
            //Your IO code goes here to create a file and set to outputStream//

        }
    }

Ensure you push your file contents to **outputStream** .

Answer 3

To complete the answer of number one item in the io part...

you can refer to this link

http://www.programcreek.com/2009/02/java-convert-a-file-to-byte-array-then-convert-byte-array-to-a-file/

or refer to this code

File file = new File(enter the filepath here)
FileInputStream fis = new FileInputStream(file);
                ByteArrayOutputStream bos = new ByteArrayOutputStream();
                byte[] buf = new byte[1024];
                try {
                    for (int readNum; (readNum = fis.read(buf)) != -1;) {
                        bos.write(buf, 0, readNum); //no doubt here is 0
                        //Writes len bytes from the specified byte array starting at offset off to this byte array output stream.
                        System.out.println("read " + readNum + " bytes,");
                    }
                } catch (IOException ex) {
                    System.err.println("unable to convert to bytes");
                }
                byte[] bytes = bos.toByteArray();
                outputStream.write(bytes);
                outputStream.flush();
                outputStream.close();

hope it helps!

Answer 4

You can try ClientIO to read and write files on the client with GWT

http://www.emitrom.com/blog/client-io