easy karma (file download)

[Jarrod Pritchard]

Hi everyone. Im a student at RIT who is trying to over-achieve. Im working on an open source project, and although a lot of it is over my head, im holding my own pretty well( i survived the JDBC). Except for this part. I need to connect to the internet, download a file, and save it. I've written methods for calculating its size, MD5, all of that, but now after putting it off, i have to figure out how to download it. Just for completeness - The program is pulling the URL from a MySQL database, then connecting and downloading a program and checking its size, MD5, etc. Im stuck. Ive googled for a day now, and been through the Java Ranch, and I am lost.

Thanks alot, these forums have been INVALUABLE to learning java here at RIT.

lurch

[Ernest Friedman-Hill]

Hi,

Welcome to JavaRanch!

The java.net.URL class is your friend. The precise code you'd use depends on what you want to do with the downloaded data -- put it into a file, for example, or store it in a database -- but here's one simple version:

    try {
        URL url = new URL("http://www.foo.com/program.exe");
        InputStream stream = url.openStream();
        byte[] buffer = new byte[1000];
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        int count;
        while ((count = stream.read(buffer)) >= 0) {
            baos.write(buffer, 0, count);
        }
        stream.close();
       
        // data is the contents of the file
        byte[] data = baos.toByteArray();
        // Do something with data here!
    } catch (MalformedURLException e) {
        // handle this
    } catch (IOException e) {
        // handle this
    }