java swing 绘制简单的运动圆- 2019-11-18 23:25:03- java: java,game,游戏,swing
    —-
    思考：
    1.为什么我没有想到要提供canvasWidth和canvasHeight的get方法？而且只提供get方法？为什么不提供set方法？
    因为canvasWidth和canvasHeight是窗口的宽和高，给外部提供set方法之后，就可以被外部随意修改产生安全问题。
    2.画板的部分为什么提供内部类？
    因为画板是这个窗口的一部分。

    1. /**
    2.  * 入口启动
    3.  */
    4. public static void main(String[] args) {
    5.    int sceneWidth = 800;
    6.     int sceneHeight = 800;
    7.     int count = 10;
    8.     MyCircleRun myCircleRun = new MyCircleRun(sceneWidth, sceneHeight, count);
    9.     myCircleRun.run("我的圈圈");
    10. }
    11. /**
    12.  * 启动类
    13.  * @Author Bai
    14.  * @Date 2019-11-24 18:12
    15.  */
    16. public class MyCircleRun {
    17.     /**
    18.      * 窗口宽
    19.      */
    20.     private Integer sceneWidth;
    21.     /**
    22.      * 窗口高
    23.      */
    24.     private Integer sceneHeight;
    25.     /**
    26.      * 要绘制的数据
    27.      */
    28.     private Circle[] circles;
    29.     public MyCircleRun(int sceneWidth, int sceneHeight, int count) {
    30.         this.sceneHeight = sceneHeight;
    31.         this.sceneWidth = sceneWidth;
    32.         circles = new Circle[count];
    33.         double r = 70;
    34.         for (int i = 0; i < count; i++) {
    35.             //sceneWidth - 2 * r  画布的宽-直径 作为随机取值的最大值  +r是为了不让圆在画布边缘随生成
    36.             double x = (Math.random() * (sceneWidth - 2 * r)) + r;
    37.             double y = (Math.random() * (sceneHeight - 2 * r)) + r;
    38.             //随机生成速度
    39.             double vx = (Math.random() * 11) - 5;
    40.             double vy = (Math.random() * 11) - 5;
    41.             circles[i] = new Circle(x, y, r, vx, vy);
    42.         }
    43.     }
    44.     public void run(String windowTitle) {
    45.         EventQueue.invokeLater(() -> {
    46.             MyCircleJFrame frame = new MyCircleJFrame(windowTitle, sceneWidth, sceneHeight);
    47.             new Thread(() -> {
    48.                 // TODO: 2019/11/24 为什么用循环？ 不停的重新绘制
    49.                 while (true) {
    50.                     // 绘制数据
    51.                     frame.render(circles);
    52.                     AlgoVisHelper.pause(20);
    53.                     // 更新数据（重新绘制后生效）
    54.                     for (Circle circle : circles) {
    55.                         circle.move(sceneWidth, sceneHeight);
    56.                     }
    57.                 }
    58.             }).start();
    59.         });
    60.     }
    61. }
    62. /**
    63.  * 要绘制的类
    64.  */
    65. @Data
    66. public class Circle {
    67.     private double x;
    68.     private double y;
    69.     private double r;
    70.     private double xv;
    71.     private double yv;
    72.     public Circle(double x, double y, double r, double xv, double yv) {
    73.         this.x = x;
    74.         this.y = y;
    75.         this.r = r;
    76.         this.xv = xv;
    77.         this.yv = yv;
    78.     }
    79.     /**
    80.      * 移动
    81.      */
    82.     public void move(int sceneWidth, int sceneHeight) {
    83.         //碰到画布边缘自动弹回来
    84.         //计算最小边缘
    85.         double yMin = r;
    86.         double xMin = r;
    87.         //计算最大边缘
    88.         double yMax = sceneHeight - r;
    89.         double xMax = sceneWidth - r;
    90.         //移动速度可以是负的 往反方向移动
    91.         if (x >= xMax || x <= xMin) {
    92.             xv = -xv;
    93.         }
    94.         if (y >= yMax || y <= yMin) {
    95.             yv = -yv;
    96.         }
    97.         x += xv;
    98.         y += yv;
    99.     }
    100. }
    101. /**
    102.  * 绘制工具类
    103.  */
    104. public class AlgoVisHelper {
    105.     private AlgoVisHelper() {
    106.     }
    107.     public static void strokeCircle(Graphics2D g, double x, double y, double r) {
    108.         Ellipse2D circle = new Ellipse2D.Double(x - r, y - r, 2 * r, 2 * r);
    109.         g.draw(circle);
    110.     }
    111.     public static void fillCircle(Graphics2D g, int x, int y, int r) {
    112.         Ellipse2D circle = new Ellipse2D.Double(x - r, y - r, 2 * r, 2 * r);
    113.         g.fill(circle);
    114.     }
    115.     public static void setColor(Graphics2D g, Color color) {
    116.         g.setColor(color);
    117.     }
    118.     public static void setStrokeWidth(Graphics2D g, int w) {
    119.         int strokeWidth = w;
    120.         g.setStroke(new BasicStroke(strokeWidth, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
    121.     }
    122.     /**
    123.      * 绘制等待时间
    124.      *
    125.      * @param t
    126.      */
    127.     public static void pause(int t) {
    128.         try {
    129.             Thread.sleep(t);
    130.         } catch (InterruptedException e) {
    131.             System.out.println("Error sleeping");
    132.         }
    133.     }
    134. }