// CSE 143, Winter 2009, Marty Stepp
// A Downloader object is able to read a given URL and download it to a file.
// This class demonstrates opening input streams to read from URLs, opening an
// output stream to write to a file, and method headers that throw exceptions.

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

public class Downloader {
    private URL url;
    
    // Constructs a new downloader to read from the URL with the given text
    // representation, such as "http://www.google.com/".
    // Throws a MalformedURLException if this is not a valid URL.
    public Downloader(String urlString) throws MalformedURLException {
        url = new URL(urlString);
    }
    
    // Reads from this downloader's URL and writes its contents to the given file.
    // Throws an IOException if there is any error while reading/writing data.
    public void download(String targetFileName) throws IOException {
        InputStream in = url.openStream();
        FileOutputStream out = new FileOutputStream(targetFileName);
        while (true) {
            int n = in.read();
            if (n == -1) {   // -1 means end-of-file
                break;
            }
            out.write(n);
        }
        in.close();
        out.close();
    }
}