Java7u40 中的 javax.swing.Timer 变慢

Question

同时调用 javax.swing.Timer#start()，

7u25 没问题。

但是 7u40 是个大问题。

调用 ActionListener#actionPerformed 太慢了。 (基本上同时调用u25)

u25 和 u40 之间完全不同的移动。 (我使用 Windows 8)我报告错误但仍未添加错误跟踪系统。甲骨文粉碎 Swing 应用程序？

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class TimerProblem extends JComponent {

        int red = 0;

        TimerProblem(final long startMs) {
                setPreferredSize(new Dimension(10, 10));

                Timer t = new Timer(16, new ActionListener() {

                        @Override
                        public void actionPerformed(ActionEvent e) {
                                red = (int)(System.currentTimeMillis() - startMs) % 255;
                                repaint();
                        }

                });
                t.setInitialDelay(1000);
                t.start();
        }

        @Override
        protected void paintComponent(Graphics g) {
                g.setColor(new Color(red, 255 - red, 0));
                g.fillRect(0, 0, getWidth(), getHeight());
        }

        public static void main(String[] args) {
                JFrame f = new JFrame();
                Container c = f.getContentPane();

                c.setLayout(new GridLayout(10, 10));
                long startMs = System.currentTimeMillis();
                for (int i = 0; i < 100; i++) {
                        c.add(new TimerProblem(startMs));
                }
                f.pack();
                f.setVisible(true);
        }

}

Answer 1

您的示例中出现了几个问题:

• Swing GUI 对象应该仅在 event dispatch thread 上构造和操作.

• All Swing Timer实例共享一个正在饱和的公共(public)线程。

根据目标，一些替代方案是可能的:

• 使用单个 Timer 实例，并选择一些分数以更高的比例进行更新。下面的示例随机选择 N 个组件并每 100 毫秒更新一次。

• 使用TexturePaint，如图here .

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import javax.swing.*;

/** @see https://stackoverflow.com/a/18936444/230513 */
public class BlinkenLights {

    private static final int S = 24;
    private static final int N = 10;
    private static final Random r = new Random();
    private static final List<MyComponent> list = new ArrayList<MyComponent>();

    private static final class MyComponent extends JComponent {

        public MyComponent() {
            this.setOpaque(true);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(S, S);
        }

        @Override
        protected void paintComponent(Graphics g) {
            g.setColor(Color.getHSBColor(r.nextFloat() / 6, 1, 1));
            g.fillRect(0, 0, getWidth(), getHeight());
        }
    }

    private static JPanel createPanel() {
        final JPanel p = new JPanel();
        p.setLayout(new GridLayout(N, N));
        for (int i = 0; i < N * N; i++) {
            MyComponent c = new MyComponent();
            p.add(c);
            list.add(c);
        }
        Timer t = new Timer(1000 / N, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                Collections.shuffle(list, r);
                for (int i = 0; i < N; i++) {
                    list.get(i).repaint();
                }
            }
        });
        t.start();
        return p;
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame f = new JFrame();
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                f.add(createPanel());
                f.pack();
                f.setLocationRelativeTo(null);
                f.setVisible(true);
            }
        });
    }
}