学步园

     java画时钟，难点在与计算各点的坐标值，这些计算都与高中所学的几何图形有关。这里的时钟小程序，是从网上搜索到的，这里只是整理了一下。加了点注视，易于理解。

  先来看下运行的结果截图：

界面还是比较好看的。

下面贴出代码：

package com.mengke.j2se.scpture;


import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.Ellipse2D;
import java.awt.geom.GeneralPath;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.util.Calendar;
import java.util.Date;

import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.UIManager;

public class Clock extends JComponent {
	private static final Color INTEGRAL_COLOR = new Color(0, 128, 128);
	private int radius;//半径
	private double s = 0.03;
	private Calendar currentTime = Calendar.getInstance();
	

	public Clock(int radius) {
		this.radius = radius;
	}

	public void setCurrentTime(Date time) {
		this.currentTime.setTime(time);
	}

	public void setCurrentTime(long millis) {
		this.currentTime.setTimeInMillis(millis);
	}

	public Dimension getPreferredSize() {
		Insets insets = getInsets();
		int r = (int) (radius == -1 ? 0 : radius * (1 + s)) + 1;
		return new Dimension(r * 2 + insets.left + insets.right, r * 2 + insets.top + insets.bottom);
	}

	protected void paintComponent(Graphics g) {
		super.paintComponent(g);
		Graphics2D g2d = (Graphics2D) g;
		//反锯齿开关开
		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		Insets insets = getInsets();
		int wid = getWidth() - insets.left - insets.right;
		int hei = getHeight() - insets.top - insets.bottom;
		int r = (int) ((Math.min(wid, hei)) / 2 / (1 + s));
		g2d.translate(insets.left + r * (1 + s), insets.top + r * (1 + s));
		g2d.scale(1, -1);
		//画60个点
		for (int i = 0; i < 60; i++) {
			int angle = 90 - i * 6;
			double pos[] = calcPos(r, angle);
			paintMinuteDot(r, g2d, pos[0], pos[1], i % 5 == 0);
		}
		//画时针
		paintHourPointer(r, g2d);
		
		//画分针
		paintMinutePointer(r, g2d);
		
		//画秒针
		paintSecondPointer(r, g2d);
		//画中间点
		paintCenterPoint(g2d);
		g2d.scale(1, -1);
		g2d.translate(-insets.left - r * (1 + s), -insets.top - r * (1 + s));
	}

	/*
	 * 画时钟中间那一点
	 * @param g2d
	 */
	private void paintCenterPoint(Graphics2D g2d) {
		g2d.setColor(Color.BLUE);
		Rectangle2D rect = new Rectangle2D.Double(-2, -2, 4, 4);
		g2d.fill(rect);
	}

	/*
	 * 画分针
	 * @param r
	 * @param g2d
	 */
	private void paintMinutePointer(int r, Graphics2D g2d) {
		int minute = currentTime.get(Calendar.MINUTE);
		int second = currentTime.get(Calendar.SECOND);
		double angle = 90 - (minute + second / 60.0) * 6;
		Shape pointerShape = createPointerShape(r * 0.8, r * 0.04, r * 0.08, angle);
		g2d.setColor(Color.LIGHT_GRAY);
		g2d.fill(pointerShape);
		g2d.setColor(Color.DARK_GRAY);
		g2d.draw(pointerShape);
	}

	/*
	 * 画时针
	 * @param r
	 * @param g2d
	 */
	private void paintHourPointer(int r, Graphics2D g2d) {
		int hour = currentTime.get(Calendar.HOUR);
		int minute = currentTime.get(Calendar.MINUTE);
		int second = currentTime.get(Calendar.SECOND);
		double angle = 90 - (hour + minute / 60.0 + second / 3600.0) * 30;
		Shape pointerShape = createPointerShape(r * 0.6, r * 0.06, r * 0.1, angle);
		g2d.setColor(Color.LIGHT_GRAY);
		g2d.fill(pointerShape);
		g2d.setColor(Color.DARK_GRAY);
		g2d.draw(pointerShape);
	}

	/*
	 * 创建指针路径多变形
	 * @param r1 从圆心到指针定点的长度
	 * @param r2 从圆心到指针侧边端点的距离
	 * @param r3 从圆心到指针尾部端点的距离
	 * @param angle 指针角度
	 * @return
	 */
	private Shape createPointerShape(double r1, double r2, double r3, double angle) {
		GeneralPath gp = new GeneralPath();
		double[] pos = calcPos(r1, angle);//指针定点
		double[] pos1 = calcPos(r2, angle + 90);//指针侧边断点
		gp.append(new Line2D.Double(pos[0], pos[1], pos1[0], pos1[1]), true);
		double[] pos2 = calcPos(r3, angle + 180);//指针尾部
		gp.lineTo((float) pos2[0], (float) pos2[1]);
		double[] pos3 = calcPos(r2, angle + 270);//指针的另一侧边断点
		gp.lineTo((float) pos3[0], (float) pos3[1]);
		gp.closePath();
		return gp;
	}
	
	/*
	 *画秒针 
	 * @param r
	 * @param g2d
	 */
	private void paintSecondPointer(int r, Graphics2D g2d) {
		g2d.setColor(Color.BLACK);
		int second = currentTime.get(Calendar.SECOND);
		int angle = 90 - second * 6;
		double pos[] = calcPos(r * 0.9, angle);
		double pos1[] = calcPos(r * 0.2, angle + 180);
		Line2D line = new Line2D.Double(pos1[0], pos1[1], pos[0], pos[1]);
		g2d.draw(line);
	}

	/**
	 * 画代表每一分钟的点。
	 * @param r
	 * @param g2d
	 * @param x
	 * @param y
	 * @param flag
	 */
	private void paintMinuteDot(int r, Graphics2D g2d, double x, double y, boolean flag) {
		g2d.setColor(flag ? Color.RED : Color.BLACK);
		if (flag) {
			Ellipse2D rect = new Ellipse2D.Double(x - r * s, y - r * s, r * s * 2, r * s * 2);
			g2d.fill(rect);
		} else {
			Ellipse2D rect = new Ellipse2D.Double(x - r * 0.02, y - r * 0.02, r * 0.04, r * 0.04);
			g2d.fill(rect);
		}
	}

	/*
	 *根据半径和角度计算点的坐标 
	 * @param r
	 * @param angle
	 * @return
	 */
	private double[] calcPos(double r, double angle) {
		double radian = Math.toRadians(angle);
		double x = r * Math.cos(radian);
		double y = r * Math.sin(radian);

		return new double[] { x, y };
	}

	/**
	 * 显示界面
	 */
	public void showUI(){
		new Thread() {
			public void run() {
				while (true) {
					try {
						Thread.sleep(1000);
					} catch (InterruptedException ex) {
						ex.printStackTrace();
					}
					setCurrentTime(System.currentTimeMillis());
					repaint();
				}
			}
		}.start();
	}
	public static void main(String[] args) {
		try {
			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
		} catch (Exception e) {
			e.printStackTrace();
		}
		final Clock clock = new Clock(50);
		clock.showUI();
		clock.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
		JFrame f = new JFrame("GDI+时钟");
		f.add(clock, BorderLayout.CENTER);
		f.pack();
		f.setLocationRelativeTo(null);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.setVisible(true);
	}
}