Question

I am trying to download an exe file with following code, any idea why it downloads only ~30% of the file? At least it doesn’t throw any exceptions.

My main method looks like this: new DownloadWorker().execute();

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;

import javax.swing.SwingWorker;

public final class DownloadWorker extends SwingWorker<Object, Object> {

    @Override
    protected Object doInBackground() throws Exception {
        BufferedInputStream in = null;
        BufferedOutputStream out = null;

        try {
            URL url = new URL("http://download.piriform.com/ccsetup320.exe");
            URLConnection conn = url.openConnection();
            conn.connect();

            int fileLength = conn.getContentLength();

            in = new BufferedInputStream(url.openStream());
            out = new BufferedOutputStream(new FileOutputStream("ccsetup320.exe"));

            byte[] buffer = new byte[4096];
            long total = 0;
            int bytesRead = 0;
            while ( (bytesRead = in.read(buffer)) != -1 ) {
                total += bytesRead;
                System.out.println((int) (total * 100 / fileLength));
                out.write(buffer, 0, bytesRead);
            }
        } catch ( Exception e ) {
            e.printStackTrace();
        } finally {
            if ( out != null ) {
                out.flush();
                out.close();
            }
            if ( in != null ) {
                in.close();
            }
        }

        return null;
    }

    @Override
    protected void done() {

    }

}

Thanks.

Answer 1

Have you tried using Java NIO seen as you have Java 7 installed:

import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URL;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;


public class TestApp {

    public static void main(String[] args) {
        try {
            URL url = new URL("http://download.piriform.com/ccsetup320.exe");
            ReadableByteChannel rbc = Channels.newChannel(url.openStream());
            FileOutputStream fos = new FileOutputStream("c:/ccsetup320.exe");
            fos.getChannel().transferFrom(rbc, 0, 1 << 24);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

}

The above code is tested and works just fine, I got it from a similar question found here we can see how the NIO makes coding so much easier 🙂

EDIT:

I have updated the code to use a swingworker and it downloads the file without a problem:

import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URL;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import javax.swing.SwingWorker;

public class JavaApplication174 {

    public static void main(String[] args) {
        SwingWorker worker = new SwingWorker() {

            @Override
            protected Object doInBackground() throws Exception {

                try {
                    URL google = new URL("http://download.piriform.com/ccsetup320.exe");
                    ReadableByteChannel rbc = Channels.newChannel(google.openStream());
                    FileOutputStream fos = new FileOutputStream("c:/ccsetup320.exe");
                    fos.getChannel().transferFrom(rbc, 0, 1 << 24);
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
                return this;
            }
        };
        worker.run();
    }
}

EDIT 2:

You call execute() on your workers instance use run() instead works for me!