问高DPI屏幕上的Java Swing

EN

import java.awt.EventQueue;
import java.awt.Font;
import java.util.Set;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                setDefaultSize(24);

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new JLabel("Happy as a pig in a blanket"));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public static void setDefaultSize(int size) {

        Set<Object> keySet = UIManager.getLookAndFeelDefaults().keySet();
        Object[] keys = keySet.toArray(new Object[keySet.size()]);

        for (Object key : keys) {

            if (key != null && key.toString().toLowerCase().contains("font")) {

                System.out.println(key);
                Font font = UIManager.getDefaults().getFont(key);
                if (font != null) {
                    font = font.deriveFont((float)size);
                    UIManager.put(key, font);
                }

            }

        }

    }

}