import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
public class Main {
public static void main(String[] args) throws IOException {
final int SCALE = 2;
Image img = new ImageIcon(new URL("http://www.w3cschool.cn/style/download.png")).getImage();
BufferedImage bi = new BufferedImage(SCALE * img.getWidth(null), SCALE
* img.getHeight(null), BufferedImage.TYPE_INT_ARGB);
Graphics2D grph = (Graphics2D) bi.getGraphics();
grph.scale(SCALE, SCALE);
grph.drawImage(img, 0, 0, null);
grph.dispose();
ImageIO.write(bi, "png", new File("double_size.png"));
}
}