java 钟_java实现时钟效果

要实现一个时钟效果，可以使用 Java 的 Graphics2D 类来绘制时钟的各个部分。

首先需要创建一个 JFrame 窗口，并在其中添加一个 JPanel 用于绘制时钟。然后在 JPanel 中重写 paintComponent 方法，在该方法中使用 Graphics2D 绘制时钟的各个部分。

以下是一个简单的 Java 时钟实现示例代码：

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.Ellipse2D;
import java.time.LocalTime;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Clock extends JPanel {
    private LocalTime time;

    public Clock() {
        time = LocalTime.now();
    }

    public void setTime(LocalTime time) {
        this.time = time;
        repaint();
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        Graphics2D g2d = (Graphics2D) g.create();

        // 抗锯齿
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // 获取面板尺寸
        int width = getWidth();
        int height = getHeight();

        // 计算时钟半径
        int radius = Math.min(width, height) / 2 - 5;

        // 将原点移动到面板中心
        g2d.translate(width / 2, height / 2);

        // 绘制时钟外框
        g2d.setStroke(new BasicStroke(3));
        g2d.setColor(Color.BLACK);
        g2d.draw(new Ellipse2D.Double(-radius, -radius, radius * 2, radius * 2));

        // 绘制时钟刻度
        for (int i = 0; i < 12; i++) {
            double angle = i * Math.PI / 6;
            int x1 = (int) (Math.cos(angle) * (radius - 20));
            int y1 = (int) (Math.sin(angle) * (radius - 20));
            int x2 = (int) (Math.cos(angle) * radius);
            int y2 = (int) (Math.sin(angle) * radius);
            g2d.drawLine(x1, y1, x2, y2);
        }

        // 绘制时钟指针
        int hour = time.getHour() % 12;
        int minute = time.getMinute();
        int second = time.getSecond();

        double hourAngle = (hour + minute / 60.0) * Math.PI / 6;
        int hourLength = (int) (radius * 0.5);
        int hourX = (int) (Math.cos(hourAngle) * hourLength);
        int hourY = (int) (Math.sin(hourAngle) * hourLength);
        g2d.setStroke(new BasicStroke(5));
        g2d.setColor(Color.BLACK);
        g2d.drawLine(0, 0, hourX, hourY);

        double minuteAngle = minute * Math.PI / 30;
        int minuteLength = (int) (radius * 0.7);
        int minuteX = (int) (Math.cos(minuteAngle) * minuteLength);
        int minuteY = (int) (Math.sin(minuteAngle) * minuteLength);
        g2d.setStroke(new BasicStroke(3));
        g2d.setColor(Color.BLUE);
        g2d.drawLine(0, 0, minuteX, minuteY);

        double secondAngle = second * Math.PI / 30;
        int secondLength = (int) (radius * 0.9);
        int secondX = (int) (Math.cos(secondAngle) * secondLength);
        int secondY = (int) (Math.sin(secondAngle) * secondLength);
        g2d.setStroke(new BasicStroke(1));
        g2d.setColor(Color.RED);
        g2d.drawLine(0, 0, secondX, secondY);

        g2d.dispose();
    }

    public static void main(String[] args) throws InterruptedException {
        JFrame frame = new JFrame("Clock");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 300);

        Clock clock = new Clock();
        frame.add(clock);

        frame.setVisible(true);

        while (true) {
            clock.setTime(LocalTime.now());
            Thread.sleep(1000);
        }
    }
}

该代码使用了 Ellipse2D、Line2D 等几何图形类来绘制时钟的各个部分，同时使用了 Stroke 类来设置画笔的粗细。在主函数中使用一个 while 循环不断更新时钟时间并刷新画面，实现了一个简单的时钟效果。