Java swing 中的定时器

Question

我正在尝试用 java swing timer 替换 Thread.sleep()，因为我听说这对图形来说更好。

以前，我有这样的设置，但它会干扰图形。

while(counter < array.size){
Thread.sleep(array.get(counter).startTime);
//do first task
Thread.sleep(array.get(counter).secondTime);
//do second task
Thread.sleep(array.get(counter).thirdTime);
//do third task
counter++
}

现在，我正在尝试用其中之一替换每个Thread.sleep()，然后我有在此之后发生的实际事件，但它似乎根本没有等待。

int test = array.get(counter).time;
ActionListener taskPerformer = new ActionListener(){
public void actionPerformed(ActionEvent evt){
}
};
Timer t = new Timer(test, taskPerformer);
t.setRepeats(false);
t.start();

基本上，我如何确保程序在不给它任何代码以在计时器内执行的情况下等待？谢谢！

Answer 1

答案归结为您想要实现的目标......

要记住的重要一点是，Swing 是单线程环境，也就是说，所有对 UI 的交互、更改、修改、更新和创建都是在事件调度线程的上下文中完成的。

任何阻止 EDT 的操作（例如 sleep、wait 等）都会阻止 EDT 重新绘制 UI 或响应新事件。

实现此目的的一种方法是使用javax.swing.Timer

这是一个非常简单的例子，它使用了 3 个链接在一起的计时器。就个人而言，我会使用一个为短时间滴答配置的单个计时器，并检查是否发生了所需的延迟，然后相应地更改状态，但这得到了重点......

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class SimpleTimer {

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

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

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private Timer red;
        private Timer green;
        private Timer yellow;
        private Color color = Color.GREEN;

        private Point spot;

        public TestPane() {
            red = new Timer(500, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    color = Color.RED;
                    green.start();
                    repaint();
                }
            });
            green = new Timer(2000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    color = Color.GREEN;
                    yellow.start();
                    repaint();
                }
            });
            yellow = new Timer(1000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    color = Color.YELLOW;
                    red.start();
                    repaint();
                }
            });
            red.setRepeats(false);
            green.setRepeats(false);
            yellow.setRepeats(false);
            green.start();

            addMouseMotionListener(new MouseAdapter() {
                @Override
                public void mouseMoved(MouseEvent e) {
                    spot = e.getPoint();
                    repaint();
                }
            });

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            int radius = 20;
            int x = (getWidth() - radius) / 2;
            int y = (getHeight() - radius) / 2;
            g2d.setColor(color);
            g2d.fillOval(x, y, radius, radius);

            if (spot != null) {

                x = spot.x - 5;
                y = spot.y - 5;
                g2d.setColor(Color.RED);
                g2d.drawOval(x, y, 10, 10);
                g2d.setColor(Color.YELLOW);
                g2d.fillOval(x, y, 10, 10);

            }

            g2d.dispose();
        }
    }
}

另一种选择是使用SwingWorker，这允许在后台线程中进行某种处理（让 EDT 保持运行），但提供了可以简单地将结果同步回 EDT 的方法。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class SimpleTimer {

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

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

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private Color color = Color.GREEN;

        private Point spot;

        public TestPane() {

            new Switcher().execute();

            addMouseMotionListener(new MouseAdapter() {
                @Override
                public void mouseMoved(MouseEvent e) {
                    spot = e.getPoint();
                    repaint();
                }
            });

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            int radius = 20;
            int x = (getWidth() - radius) / 2;
            int y = (getHeight() - radius) / 2;
            g2d.setColor(color);
            g2d.fillOval(x, y, radius, radius);

            if (spot != null) {

                x = spot.x - 5;
                y = spot.y - 5;
                g2d.setColor(Color.RED);
                g2d.drawOval(x, y, 10, 10);
                g2d.setColor(Color.YELLOW);
                g2d.fillOval(x, y, 10, 10);

            }

            g2d.dispose();
        }

        public class Switcher extends SwingWorker<Void, Color> {

            @Override
            protected void process(List<Color> chunks) {
                color = chunks.get(chunks.size() - 1);
                repaint();
            }

            @Override
            protected Void doInBackground() throws Exception {

                while (true) {

                    publish(Color.GREEN);
                    Thread.sleep(2000);
                    publish(Color.YELLOW);
                    Thread.sleep(500);
                    publish(Color.RED);
                    Thread.sleep(2000);

                }

            }

        }

    }
}

查看Concurrency in Swing了解更多详情