【 Java 】 简易交通灯

起因：

很久之前就想做做这类的小程序练手，现在才开始动工哈哈哈。

从最简单的开始做起，这次是一个交通灯。

实现了交通灯的简单显示转换循环功能。

基于 java.swing 。

先上效果图。超级超级超级简陋哈哈哈

红灯                                                                     黄灯                                                                        绿灯

                              

上代码

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/** 
 * @ClassName: TrafficLights 
 * @Description: 实现简单的交通灯转换功能
 * @author Arrack
 * @date 2018年1月30日 上午9:49:54 
 *  
 */
public class TrafficLights extends JPanel {
    /* 
     * serialVersionUID
     * 相当于java类的身份证。主要用于版本控制。
     * serialVersionUID作用是序列化时保持版本的兼容性,
     * 即在版本升级时反序列化仍保持对象的唯一性。
     * 摘自百度知道 https://zhidao.baidu.com/question/321447087.html
     */
    private static final long serialVersionUID = 1L;

    /*
     * 定义一系列静态常量
     * 程序窗口宽度高度，三种颜色亮灯，为空（都熄灭）
     */
    private static final int winWidth = 500;
    private static final int winHeight = 300;
    private static final int BLANK = 0;
    private static final int RED = 1;
    private static final int YELLOW = 2;
    private static final int GREEN = 3;

    private static int color = BLANK; // 将初始状态设置为都熄灭状态

    /*
     * 计算灯的位置和大小（仅与窗口高度和宽度有关）
     * ps：绘制椭圆时，drawOval(int x, int y, int width, int height)
     *     x,y 为椭圆外接矩形左上顶点的坐标,width,height为矩形两边长。
     */
    private int ballWidth = winHeight / 3;
    private int ballX = winWidth / 2 - ballWidth / 2 - winWidth / 50,
            ballY = winHeight / 2 - ballWidth + winHeight / 15;
    private int ballPadding = (winWidth - 3 * ballWidth) / 4;
    private int yellowX = ballX;
    private int redX = ballX - ballPadding - ballWidth;
    private int greenX = ballX + ballPadding + ballWidth;

    /*
     * Label 倒计时指示
     */
    private JLabel l = new JLabel("");

    public TrafficLights() {
        l.setFont(new Font("Arial", Font.BOLD, 20));
        add(l);
    }

    /** 
     * @Title: changeLights 
     * @Description: 利用timer类，进行灯的变换和闪烁，并显示倒计时
     * @param @param timeR  红灯持续时间 单位秒
     * @param @param timeY  黄灯持续时间
     * @param @param timeG  绿灯持续时间
     * @return void
     */
    public void changeLights(final int timeR, final int timeY, final int timeG) {
        final Timer timer = new Timer();
        final int num = timeR + timeG + timeY;
        timer.schedule(new TimerTask() {
            int i = 1;

            public void run() {
                i %= num;
                if (i > 0 && i <= timeR) { // 红灯的时间，红灯持续亮
                    color = RED;
                    l.setText(Integer.toString(timeR + 1 - i));
                } else if (i > timeR && i <= timeR + timeY) { // 黄灯的时间，黄灯闪烁，0.6s闪一次
                    color = YELLOW;
                    l.setText(Integer.toString(timeY + 1
                            - (i % timeY != 0 ? i % timeY : timeY)));
                    timer.schedule(new TimerTask() {
                        public void run() {
                            color = BLANK;
                            repaint();
                        }
                    }, 600);
                } else { // 绿灯的时间，持续亮
                    color = GREEN;
                    l.setText(Integer.toString(timeG + 1
                            - (i % timeG != 0 ? i % timeG : timeG)));
                }
                repaint();
                i++;
            }
        }, 0, 1000);

    }

    /*
     * Title: paintComponent
     * Description: 重写绘制内容函数，利用switch选取显示内容（遮挡方式）
     * @param g 
     * @see javax.swing.JComponent#paintComponent(java.awt.Graphics) 
     */
    protected void paintComponent(Graphics g) {

        super.paintComponent(g);

        g.setColor(Color.RED);
        g.fillOval(redX, ballY, ballWidth, ballWidth);
        g.setColor(Color.YELLOW);
        g.fillOval(yellowX, ballY, ballWidth, ballWidth);
        g.setColor(Color.GREEN);
        g.fillOval(greenX, ballY, ballWidth, ballWidth);
        g.setColor(this.getBackground());
        switch (color) {
        case RED:
            g.fillRect(yellowX, ballY, greenX - yellowX + ballWidth, ballWidth);
            g.setColor(Color.BLACK);
            g.drawOval(yellowX, ballY, ballWidth, ballWidth);
            g.drawOval(greenX, ballY, ballWidth, ballWidth);
            break;
        case YELLOW:
            g.fillRect(redX, ballY, ballWidth, ballWidth);
            g.fillRect(greenX, ballY, ballWidth, ballWidth);
            g.setColor(Color.BLACK);
            g.drawOval(redX, ballY, ballWidth, ballWidth);
            g.drawOval(greenX, ballY, ballWidth, ballWidth);
            break;
        case GREEN:
            g.fillRect(redX, ballY, yellowX - redX + ballWidth, ballWidth);
            g.setColor(Color.BLACK);
            g.drawOval(redX, ballY, ballWidth, ballWidth);
            g.drawOval(yellowX, ballY, ballWidth, ballWidth);
            break;
        case BLANK:
            g.fillRect(redX, ballY, greenX - redX + ballWidth, ballWidth);
            g.setColor(Color.BLACK);
            g.drawOval(redX, ballY, ballWidth, ballWidth);
            g.drawOval(yellowX, ballY, ballWidth, ballWidth);
            g.drawOval(greenX, ballY, ballWidth, ballWidth);
        default:
            break;
        }
    }

    public static void main(String[] args) {
        JPanel p = new TrafficLights();
        JFrame frame = new JFrame("交通灯");
        frame.getContentPane().add(p);
        frame.setSize(winWidth, winHeight);
        frame.setLocation(500, 200);
        frame.setVisible(true);
        frame.setResizable(false);
        ((TrafficLights) p).changeLights(5, 5, 5);
    }
}