Copiando um arquivo da Internet para o meu computador

Assuntos Gerais
#1

Estou usando um código fonte que achei na Internet para copiar arquivos da Internet para o meu computador mas ele sempre falha retornando -1 ao tentar pegar o tamanho do arquivo usando a função getContentLenght() da classe HttpURLConnection. Alguém sabe como posso conseguir o tamanho do arquivo usando algum outro método?

O URL que desejo fazer o download é http://www.bovespa.com.br/suplemento/ExecutaAcaoDownload.asp?arquivo=Titulos_Negociaveis.zip

Se alguém conseguir pegar o tamanho desse arquivo usando algum outro método que não seja com o getContentLenght() já me ajudaria bastante, o resto eu me viro.

Pra quem quiser dar uma checada no código fonte, segue abaixo:

Arquivo Download.java

import java.io.;
import java.net.;

class Download implements Runnable {

// Max size of download buffer.
private static final int MAX_BUFFER_SIZE = 1024;

// These are the status names.
public static final String STATUSES[] = {"Downloading",
"Complete", "Error"};

// These are the status codes.
public static final int DOWNLOADING = 0;
public static final int COMPLETE = 1;
public static final int ERROR = 2;

private URL url; // download URL
private int size; // size of download in bytes
private int downloaded; // number of bytes downloaded
private int status; // current status of download

// Constructor for Download.
public Download(URL url) {
    this.url = url;
    size = -1;
    downloaded = 0;
    status = DOWNLOADING;
    
    // Begin the download.
    download();
}

// Get this download's URL.
public String getUrl() {
    return url.toString();
}

// Get this download's size.
public int getSize() {
    return size;
}

// Get this download's progress.
public float getProgress() {
    return ((float) downloaded / size) * 100;
}

// Get this download's status.
public int getStatus() {
    return status;
}

// Mark this download as having an error.
private void error() {
    status = ERROR;
    stateChanged();
}

// Start or resume downloading.
private void download() {
    Thread thread = new Thread(this);
    thread.start();
}

// Get file name portion of URL.
private String getFileName(URL url) {
    String fileName = url.getFile();
    return fileName.substring(fileName.lastIndexOf('/') + 1);
}

// Download file.
public void run() {
    RandomAccessFile file = null;
    InputStream stream = null;
    
    try {
        // Open connection to URL.
        HttpURLConnection connection =
                (HttpURLConnection) url.openConnection();
        
        // Specify what portion of file to download.
        connection.setRequestProperty("Range",
                "bytes=" + downloaded + "-");
        
        // Connect to server.
        connection.connect();
        
        // Make sure response code is in the 200 range.
        if (connection.getResponseCode() / 100 != 2) {
            System.out.println("1");
            error();
        }
        
        // Check for valid content length.
        int contentLength = connection.getContentLength();
        if (contentLength < 1) {
            System.out.println(contentLength);
            error();
        }
        
  /* Set the size for this 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(url), "rw");
        file.seek(downloaded);
        
        stream = connection.getInputStream();
        while (status == DOWNLOADING) {
    /* Size 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 server into buffer.
            int read = stream.read(buffer);
            if (read == -1)
                break;
            
            // Write buffer to file.
            file.write(buffer, 0, read);
            downloaded += read;
            stateChanged();
        }
        
  /* Change status to complete if this point was
     reached because downloading has finished. */
        if (status == DOWNLOADING) {
            status = COMPLETE;
            stateChanged();
        }
    } catch (Exception e) {
        System.out.println(e.getMessage());
        error();
    } finally {
        // Close file.
        if (file != null) {
            try {
                file.close();
            } catch (Exception e) {}
        }
        
        // Close connection to server.
        if (stream != null) {
            try {
                stream.close();
            } catch (Exception e) {}
        }
    }
}

private void stateChanged() {
    System.out.println(STATUSES[status]);
}

}

Arquivo Dotine.java

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

public class Dotine {

private static URL verifyUrl(String url) {
    // Only allow HTTP URLs.
    if (!url.toLowerCase().startsWith("http://"))
        return null;
    
    // Verify format of URL.
    URL verifiedUrl = null;
    try {
        verifiedUrl = new URL(url);
    } catch (Exception e) {
        return null;
    }
    
    // Make sure URL specifies a file.
    if (verifiedUrl.getFile().length() < 2)
        return null;
    
    return verifiedUrl;
}

public static void main(String[] args) throws MalformedURLException, IOException {
    //http://www.bovespa.com.br/suplemento/ExecutaAcaoDownload.asp?arquivo=Titulos_Negociaveis.zip
    URL verifiedUrl = verifyUrl(args[0]);
    if (verifiedUrl != null) {
        new Download(verifiedUrl);
    } else {
        System.out.println("Invalid Download URL");
    }
}

}

#2