URL url = new URL("http://upload.wikimedia.org/wikipedia/commons/9/9c/Image-Porkeri_001.jpg");
InputStream in = new BufferedInputStream(url.openStream());
OutputStream out = new BufferedOutputStream(new FileOutputStream("Image-Porkeri_001.jpg"));

for ( int i; (i = in.read()) != -1; ) {
    out.write(i);
}
in.close();
out.close();