Download a file through the Internet with RandomAccessFile

Question

I was browsing the Internet for random Java code, and I found this source code for a download manager. It uses RandomAccessFile to download the files. The one thing I could not figure out though, was where it would download to. Here is the method that downloads the file:

public void startDownload() {
    System.out.println("Starting...");
    RandomAccessFile file = null;
    InputStream stream = null;

    try {
        URL downloadLink = new URL("http://www.website.com/file.txt");

        // Open the connection to the URL
        HttpURLConnection connection = (HttpURLConnection) downloadLink.openConnection();

        // Specify what portion of file to download
        connection.setRequestProperty("Range", "bytes=" + downloaded + "-");

        // Connect to the server
        connection.connect();

        // Make sure the code is in the 200 range
        if (connection.getResponseCode() / 100 != 2) {
            error();
        }

        // Check for valid content length
        int contentLength = connection.getContentLength();
        if (contentLength < 1) {
            error();
        }

        // Set the size for the download if it hasn't been already set
        if (size == -1) {
            size = contentLength;
            stateChanged();
        }

        // Open file and seek to the end of it
        file = new RandomAccessFile(getFileName(downloadLink), "rw");  
              // getFileName returns the name of the file mentioned in the URL

        file.seek(downloaded);

        stream = connection.getInputStream();

        while (status == DOWNLOADING) {
            System.out.println("Progress: " + getProgress() + "%");

            // Size the buffer according to how much of the file is left to download
            byte buffer[];
            if (size - downloaded > MAX_BUFFER_SIZE) {
                buffer = new byte[MAX_BUFFER_SIZE];
            } else {
                buffer = new byte[size - downloaded];
            }

            // Read from the server into the buffer
            int read = stream.read(buffer);
            if (read == -1) {
                break;
            }

            // Write buffer to file
            file.write(buffer, 0, read);
            downloaded += read;
            stateChanged();
        }

        if (status == DOWNLOADING) {
            status = COMPLETE;
            stateChanged();
        }


    } catch (Exception e) {
        error();
    } finally {
        // Close the stream and RAF
    }
    System.out.println("Done!");
}

I am sorry if this is obvious. I am new to the RandomAccessFile class, as I just learned of it today.

Answer 1

It will download it in the current working directory (i.e. where you run your java command) and the name of the file will be given by getFileName(downloadLink).

Answer 2

I am new to this too. getFileName appears to be a method within the same class and that code is missing.