exercise14_2.java

一款用java编写的小型数据库管理系统

import javax.swing.Timer;
import javax.swing.*;
import java.awt.*;
import java.awt.Color;
import java.awt.event.*;
public class Exercise14_2 extends JApplet {
	private JScrollBar jsbDelay = new JScrollBar();
	private JButton jbStart =new JButton("Start");
	private	  JButton jbStop=new JButton("Stop");
	private	  JButton jbReverse=new JButton("Reverse");
	  public Exercise14_2() {
		  JPanel jp1=new JPanel();
		  jp1.setLayout(new GridLayout(1,3));
		  jp1.add(jbStart);
		  jp1.add(jbStop);
		  jp1.add(jbReverse);
		  add(jp1,BorderLayout.NORTH);
		  jsbDelay.setOrientation(JScrollBar.HORIZONTAL);
		  add(jsbDelay,BorderLayout.SOUTH);
		  add(new Fans(),BorderLayout.CENTER);
		  }
	 class Fans extends JPanel{
		 int X=0;
		 private int delay = 10;  //时间间隔
		 private int Direction;  //设定方向
		 protected Timer timer = new Timer(delay, new TimerListener());
		 public Fans (){
			  jbStart.addActionListener(new ActionListener(){  //开始
		 		  public void actionPerformed(ActionEvent e){
					  setDirection(20);  //顺时针转动
		 			  timer.start();
		 			  }
			  });
			  jbStop.addActionListener(new ActionListener(){
				  public void actionPerformed(ActionEvent e){
					  timer.stop();
					  }
					  });
			  jbReverse.addActionListener(new ActionListener(){  //反转
				  public void actionPerformed(ActionEvent e){
							setDirection(-20);  //逆时针转动
							timer.start();
					  		  }
					  });
			 jsbDelay.addAdjustmentListener(new AdjustmentListener() {
			       public void adjustmentValueChanged(AdjustmentEvent e) {
			         setDelay(jsbDelay.getMaximum() - e.getValue());  //从左到右速度增大
			       }
			     });
		}

		 public void setDelay(int delay) {  //设置时间间隔
			this.delay = delay;
			timer.setDelay(delay);
		  }

		  public void setDirection(int Direction){  //设置转动的方向
			  this.Direction=Direction;
		  }

	  class TimerListener implements ActionListener {
	      public void actionPerformed(ActionEvent e) {
	        repaint();
	      }
   }
   public void paintComponent(Graphics g) {
		super.paintComponent(g);
		int xCenter = getWidth() / 2;
		int yCenter = getHeight() / 2;
		int radius =(int)(Math.min(getWidth(), getHeight()) * 0.4);
		int x = xCenter - radius;
		int y = yCenter - radius;
		g.drawOval(x-10, y-10, 2 * radius+20, 2 * radius+20);

		X-=Direction;

		g.setColor(Color.red);
		g.fillArc(x, y, 2 * radius, 2 * radius, X, 30);
		g.setColor(Color.green);
		g.fillArc(x, y, 2 * radius, 2 * radius, 90+X, 30);
		g.setColor(Color.blue);
		g.fillArc(x, y, 2 * radius, 2 * radius, 180+X, 30);
		g.setColor(Color.yellow);
		g.fillArc(x, y, 2 * radius, 2 * radius, 270+X, 30);
	}
  }
  public static void main(String[] args) {
	Exercise14_2 applet =new Exercise14_2();
    JFrame frame = new JFrame();
    frame.setTitle("Exercise14_2");
    frame.add(applet);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300, 300);
    frame.setVisible(true);
  }
}