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Java：Graphics类案例：时钟

0.前言

这几天努力往下读java，java还是蛮有趣的。分享一个图形类的案例：绘制静止的时钟，之后我使用了比较愚蠢的方法让时钟动起来，如果明天不想休息的话，会使用监听器的方式改写一下。代码总体比较简单，就懒得写注释了，反正也是书上的案例。此外，MessagePannel类也一并附上。

1.TestStillClock类(主函数入口)

				
					import javax.swing.*;
import java.awt.*;

public class TestStillClock extends JFrame {
    public  StillClock clock;
    MessagePanel message;
    public TestStillClock()
    {
        setLayout(new BorderLayout());
        clock = new StillClock();
        message = new MessagePanel(clock.getHour()+":"+clock.getMin()+":"+clock.getSec());
        message.setCentered(true);
        message.SetTransit(0,10);
        message.setForeground(Color.BLUE);
        message.setFont(new Font("Courier",Font.BOLD,16));

        add(clock);
        add(message,BorderLayout.SOUTH);

    }
    public void renew()
    {
        clock.setCurrentTime();
        message.setMessage(clock.getHour()+":"+clock.getMin()+":"+clock.getSec());
    }
    public static void main(String[] args) {
        //为什么可以随窗口大小改变是因为我们从窗口得到长宽
        TestStillClock frame = new TestStillClock();
        frame.setTitle("DisplayClock");
        frame.setSize(300,350);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        while(true )
        {
            frame.renew();
        }
    }
}

2.MessagePanel类

				
					import javax.swing.*;
import java.awt.*;

public class MessagePanel extends JPanel {
    private String message = "Welcome to Java";
    private int xCoordinate = 20;
    private int yCoordinate = 20;
    private boolean centered;
    private int interval=10;
    private int xTran=0;
    private int yTran=0;

    public MessagePanel(){};
    public MessagePanel(String m){
        this.message = m;
    }

    public String getMessage() {
        return message;
    }
    public void setMessage(String m)
    {
        this.message=m;
        repaint();
    }
    public int getxCoordinate(){
        return xCoordinate;
    }
    public void setxCoordinate(int x){
        this.xCoordinate=x;
        repaint();
    }
    public int getyCoordinate(){
        return yCoordinate;
    }
    public void setyCoordinate(int y){
        this.yCoordinate=y;
        repaint();
    }
    public boolean isCentered()
    {
        return centered;
    }
    public void setCentered(boolean f)
    {
        this.centered=f;
        repaint();
    }
    public int getInterval(){
        return interval;
    }
    public void setInterval(int i)
    {
        this.interval = i;
        repaint();
    }
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);

        if(centered)
        {
            FontMetrics fm = g.getFontMetrics();
            int sw = fm.stringWidth(message);
            int sa = fm.getAscent();
            xCoordinate = getWidth()/2-sw/2+xTran;
            yCoordinate = getHeight()/2-sa/2+yTran;
        }

        g.drawString(message,xCoordinate,yCoordinate);
    }
    public void SetTransit(int x,int y)
    {
        xTran=x;
        yTran=y;
    }
    public void moveLeft()
    {
        xCoordinate-=interval;
        repaint();
    }
    public void  moveRight()
    {
        xCoordinate+=interval;
        repaint();
    }
    public void moveUp()
    {
        yCoordinate-=interval;
        repaint();
    }
    public void moveDown(){
        yCoordinate+=interval;
        repaint();
    }
    public void move(int x,int y)
    {
        xCoordinate+=x;
        yCoordinate+=y;
        repaint();
    }
    public Dimension getPreferredSize()
    {
        return new Dimension(200,30);
    }
}

3.StillClock类

				
					import javax.swing.*;
import java.awt.*;
import java.util.Calendar;
import java.util.GregorianCalendar;

public class StillClock extends JPanel {
    private int hour;
    private int min;
    private int sec;
    public StillClock(){
        setCurrentTime();
    }
    public StillClock(int h,int m,int s)
    {
        hour=h;
        min=m;
        sec=s;
    }
    public int getHour(){
        return hour;
    }
    public int getMin(){
        return min;
    }
    public int getSec(){
        return sec;
    }
    public void setHour(int h){
        hour=h;
        repaint();
    }
    public void setMin(int m)
    {
        min=m;
        repaint();
    }
    public void setSec(int s)
    {
        sec=s;
        repaint();
    }
    public void setCurrentTime(){
        Calendar calendar = new GregorianCalendar();
        hour = calendar.get(Calendar.HOUR_OF_DAY);
        min = calendar.get(Calendar.MINUTE);
        sec = calendar.get(Calendar.SECOND);
        repaint();
    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);

        int clockRadius = (int)(Math.min(getWidth(),getHeight())*0.8*0.5);
        int xCenter = getWidth()/2;
        int yCenter = getHeight()/2;

        //DrawCircle
        g.setColor(Color.BLACK);
        g.drawOval(xCenter-clockRadius,yCenter-clockRadius,2*clockRadius,2*clockRadius);
        g.drawString("12",xCenter-5,yCenter-clockRadius+12);
        g.drawString("9",xCenter-clockRadius+3,yCenter+5);
        g.drawString("3",xCenter+clockRadius-10,yCenter+3);
        g.drawString("6",xCenter-3,yCenter+clockRadius-3);

        //Draw second hand
        int sLength = (int)(clockRadius*0.8);
        int xSecond = (int)(xCenter+sLength*Math.sin(sec*(2*Math.PI/60)));
        int ySecond = (int)(yCenter-sLength*Math.cos(sec*(2*Math.PI/60)));
        g.setColor(Color.RED);
        g.drawLine(xCenter,yCenter,xSecond,ySecond);

        //Draw min hand
        int mLength = (int)(clockRadius*0.65);
        int xMin = (int)(xCenter+mLength*Math.sin((min+sec/60.0)*(2*Math.PI/60)));
        int yMin = (int)(yCenter-mLength*Math.cos((min+sec/60.0)*(2*Math.PI/60)));
        g.setColor(Color.BLUE);
        g.drawLine(xCenter,yCenter,xMin,yMin);

        //Draw hour sec
        int hLength = (int)(clockRadius*0.5);
        int xHour = (int)(xCenter+hLength*Math.sin((hour%12+min/60.0)*(2*Math.PI/12)));
        int yHour = (int)(yCenter-hLength*Math.cos((hour%12+min/60.0)*(2*Math.PI/12)));
        g.setColor(Color.GREEN);
        g.drawLine(xCenter,yCenter,xHour,yHour);
    }
    public Dimension getPreferredSize()
    {
        return new Dimension(200,200);
    }

}

4.监听器的改进

很简单的使用Timer并添加监听器进行改进。仅有主函数更新，其余不变。

				
					import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class TestAnimationClock extends JFrame {
    public StillClock clock;
    MessagePanel message;
    public TestAnimationClock()
    {
        setLayout(new BorderLayout());
        clock = new StillClock();
        message = new MessagePanel(clock.getHour()+":"+clock.getMin()+":"+clock.getSec());
        message.setCentered(true);
        message.SetTransit(0,10);
        message.setForeground(Color.BLUE);
        message.setFont(new Font("Courier",Font.BOLD,16));

        add(clock);
        add(message,BorderLayout.SOUTH);

        Timer timer = new Timer(250,new TimerListener());
        timer.start();

    }

    private class TimerListener implements ActionListener{

        @Override
        public void actionPerformed(ActionEvent e) {
            clock.setCurrentTime();
            clock.repaint();
            message.setMessage(clock.getHour()+":"+clock.getMin()+":"+clock.getSec());
            message.repaint();
        }
    }

    public static void main(String[] args) {
        //为什么可以随窗口大小改变是因为我们从窗口得到长宽
        TestAnimationClock frame = new TestAnimationClock();
        frame.setTitle("DisplayClock");
        frame.setSize(300,350);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);

    }
}

5.效果图与碎碎念

StillClock

本来想用Java重新写一下之前的图片浏览器权当练手的，但是被Java的布局管理器搞的头昏脑涨，现在虽然壳子搭完了但是已经没有写的欲望了。

如此想想，还是python的Tkinter好用，简单清晰。

ps：最近又开始玩法环了，呜呜呜，我的梅琳娜。

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