#### 说明 canvas-nest.js 源码
地址：https://gitee.com/dgwcode/MyJavaCode/tree/master/Canvas-nest-swing
实现过程1. 绘制一个容器
2. 用随机数生成坐标，绘制100个点
3. 用随机数生成每个点的运动方向，每次x轴位移多少，y轴位移多少
4. 每1/60秒用for循环重新计算点的坐标，重绘画布
5. 两个for循环嵌套，判断每个点与其他点的距离，若小于90px，则绘制连线，且连线的rgba透明度根据距离而变化6.添加鼠标吸附事件，鼠标进入画布后实时监听其位置，并在上述for循环中判断与鼠标的距离，设点为r，距离为dist，若dist>70且dist<140，rx-=0.03xdist，r.y-=0.03y_dist，即可实现吸附效果（前半段为加速，后半段为吸附）
package main.canvas; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.Toolkit; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.MouseMotionAdapter; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.JFrame; import javax.swing.JPanel; import java.awt.BorderLayout; import java.awt.Color; public class MainFrame extends JFrame { private static final long serialVersionUID = -8808883923263763897L; private static volatile MainFrame instance; public MainFrame() { this.setTitle("Canvas Nest"); this.setSize(new Dimension(660, 470)); this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); this.setLocation((Toolkit.getDefaultToolkit().getScreenSize().width - this.getWidth()) / 2, (Toolkit.getDefaultToolkit().getScreenSize().height - this.getHeight()) / 2); this.setMinimumSize(new Dimension(400, 300)); this.setResizable(true); this.setVisible(true); this.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); /** * 100个点位置与方向的初始化 */ R[] r = new R[100]; M mousePoint = new M();//监听鼠标位置 for (int i = 0; i < r.length; i++) { r[i] = new R(); r[i].x = (float) (Math.random() * 660); r[i].y = (float) (Math.random() * 470); r[i].xa = (float) (2 * Math.random() - 1);//方向 r[i].ya = (float) (2 * Math.random() - 1);//方向 } JPanel panel = new JPanel() { private static final long serialVersionUID = -7507627235240618009L; @Override public void paint(Graphics g1) { Graphics2D g_point = (Graphics2D) g1;//点 Graphics2D g_line = (Graphics2D) g1;//线 g_point.setColor(Color.blue); // 通过键值设置渲染的抗锯齿 g_line.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g_point.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); super.paint(g_point); super.paint(g_line); for (int i = 0; i < r.length; i++) { for (int j = 0; j < r.length; j++) { // 画点 实际上可用filloval实现 g_point.drawLine((int) r[i].x, (int) r[i].y, (int) r[i].x, (int) r[i].y); if (r[i] != r[j]) { // 得到两个不同点的坐标 构成算出第三条边的长度dist float x_dist = r[i].x - r[j].x; float y_dist = r[i].y - r[j].y; float dist = (float) (x_dist * x_dist + y_dist * y_dist); // 根据距离算出透明度 float a = 0; if (dist > 0 && dist < 8100) { a = (1 - (dist / 8100)) * 100; g_line.setColor(new Color(0, 100, 150, (int) a)); g_line.drawLine((int) r[i].x, (int) r[i].y, (int) r[j].x, (int) r[j].y); } } } } } }; panel.setBackground(Color.WHITE); getContentPane().add(panel, BorderLayout.CENTER); /** * 鼠标事件处理代码 */ panel.addMouseMotionListener(new MouseMotionAdapter() { @Override public void mouseMoved(MouseEvent e) { mousePoint.x = (float) e.getX(); mousePoint.y = (float) e.getY(); } }); panel.addMouseListener(new MouseAdapter() { @Override public void mouseExited(MouseEvent e) { mousePoint.x = null; mousePoint.y = null; } }); new Thread(new Runnable() { @Override public void run() { while (true) { try { for (int i = 0; i < r.length; i++) { // 仅仅加上方向值 r[i].x += r[i].xa; r[i].y += r[i].ya; /** * 当前随机点如果在可视view中 那么 */ r[i].xa *= r[i].x > 660 || r[i].x < 0 ? -1 : 1; r[i].ya *= r[i].y > 470 || r[i].y < 0 ? -1 : 1; // 在窗口的可视大小环境中 if (mousePoint.x != null && mousePoint.y != null) { float x_dist = r[i].x - mousePoint.x; float y_dist = r[i].y - mousePoint.y; float dist = (float) (x_dist * x_dist + y_dist * y_dist); if (dist > 4900 && dist < 19600) { r[i].x -= 0.03 * x_dist; r[i].y -= 0.03 * y_dist; } } } /** * 4.每1/60秒用for循环重新计算点的坐标，重绘画布 * 5.两个for循环嵌套，判断每个点与其他点的距离， * 若小于90px，则绘制连线，且连线的rgba透明度根据距离而变化 */ panel.repaint(); Thread.sleep(1000 / 60); } catch (InterruptedException e) { e.printStackTrace(); } } } }).start(); } public static MainFrame getIstance() { if (instance == null) { synchronized (MainFrame.class) { if (instance == null) { instance = new MainFrame(); } } } return instance; } private class R { float x; float y; float xa; float ya; } private class M { Float x; Float y; } }