threadpriority.java

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

public class ThreadPriority extends JFrame implements ActionListener
{
    private PaintPanel paintPanel;
    private JPanel buttonPanel;
    private JButton startButton, stopButton;
    
    public ThreadPriority()
    {
    	super("线程优先级");
			setSize(400,300);
		
			//获取内容面板
			Container container = getContentPane();
		
			//创建绘图面板paintPanel
			paintPanel = new PaintPanel();
		
			container.add(paintPanel, BorderLayout.CENTER);
		
			//创建存放按钮的面板buttonPanel
			buttonPanel = new JPanel();
			buttonPanel.setBackground(Color.YELLOW);
		
			startButton = new JButton("开始");
			stopButton = new JButton("暂停");
			//设置按钮背景颜色
			startButton.setBackground(Color.CYAN);
			stopButton.setBackground(Color.CYAN);
			//设置字体
			startButton.setFont(new Font("Serif", Font.PLAIN, 14));
			stopButton.setFont(new Font("Serif", Font.PLAIN, 14));
		
			//注册监听器
			startButton.addActionListener(this);
			stopButton.addActionListener(this);
		
			buttonPanel.add(startButton);
			buttonPanel.add(stopButton);
		
			container.add(buttonPanel, BorderLayout.SOUTH);
		
			setVisible(true);
			setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }  
    
    public void actionPerformed(ActionEvent event)    //JButton事件处理
    {
    	if(event.getSource() == startButton)
    	{
           paintPanel.start();
           startButton.setEnabled(false);
           stopButton.setEnabled(true);
    	}
    	else if(event.getActionCommand().equals("暂停"))
    	{
    		paintPanel.suspend();
    		stopButton.setText("恢复");
    	}
    	else if(event.getActionCommand().equals("恢复"))
    	{
    		paintPanel.resume();
    		stopButton.setText("暂停");
    	}
    }
    
	public static void main(String[] args) 
	{
		ThreadPriority application = new ThreadPriority();
	}
	
	class PaintPanel extends JPanel implements Runnable
	{
		private Thread blueBall, greenBall;
		private int x1 = 10;
	    private int x2 = 10;
	    
		public PaintPanel()
		{
			super();
			setBackground(Color.WHITE);
			
			//创建两个线程
			blueBall = new Thread(this);
			greenBall = new Thread(this);
			
			//设置线程的优先级
			blueBall.setPriority(Thread.MIN_PRIORITY);
			greenBall.setPriority(Thread.MAX_PRIORITY);
		}
		
		public void paintComponent(Graphics g)
		{
			Graphics2D comp2D = (Graphics2D)g;
	        comp2D.setColor(getBackground());
	        //清除画板
	        comp2D.fillRect(0,0,getSize().width,getSize().height);
	        
	        //绘制蓝色球
	        comp2D.setColor(Color.BLUE);
	        comp2D.drawOval(x1, 30, 50, 50);
	        
	        //绘制绿色球
	        comp2D.setColor(Color.GREEN);
	        comp2D.drawOval(x2, 100, 50, 50);
		}
		
		public void run()
		{
			while(true){
	    		//如果当前线程为blueBall则执行以下代码
	    		if(Thread.currentThread() == blueBall)
	    		{
	    			x1 += 5;
	    			if(x1 >= 400)
	    				x1 = 10;
	    			//线程blueBall休眠50毫秒
	    			pause(50);
	    			//如果当前线程为greenBall则执行以下代码
	    		} 
	    		else if(Thread.currentThread() == greenBall)
	    		{
	    			x2 += 5;
	    			if(x2 >= 400)
	    				x2 = 10;
	    			//线程greenBall休眠50毫秒
	    			pause(50);
	    		}
	    		repaint();
	    	}
		}
		
		public void start()            //用于启动两个线程
		{
			greenBall.start();
			blueBall.start();
		}
		
		public void resume()           //用于将两个挂起的线程重新加入就绪队列
		{
			blueBall.resume();
			greenBall.resume();
		}
		
		public void suspend()          //用于将两个活动的线程挂起
		{
			blueBall.suspend();
			greenBall.suspend();
		}
		
		private void pause(int time)    //用于时间延时的方法
		{
	        try 
	        {
	            Thread.sleep(time);
	        } catch (InterruptedException e) { }
	    }
	}
}