1、先上素材。【键盘图片×1，wav音符×13】

链接：https://pan.baidu.com/s/1yw2-1OXDZQylzaEtD685UA
提取码：fzks

2、简述题目及思路。
今实验，遇一题，求绘制图形，添加按钮，可弹奏。

思路：采用Applet 技术绘制图形，多线程的技术输出播放奏曲子。

3、分析代码、上代码。

public class Demo04 extends Applet{
    
    
	// 键盘图片
	Image keyBoard = null;
	// 加载所有13个音符资源
	AudioClip[] notes1 = new AudioClip[7]; // a1 - g1
	AudioClip[] notes2 = new AudioClip[6];
	// 按钮
	Button[] btns = new Button[17];
	public void init() {
    
    
		keyBoard = getImage(getCodeBase(),"keyBoard.jpg");
		// 加载音频，因格式不齐，所以采用分支循环语句进行限制
		for (int i = 0; i < 7; i++) {
    
    
			notes1[i] = getAudioClip(getCodeBase(), ""+(char)(i+'a')+"1.wav");
		}
		char ch;
		int j = 0;
		for (int i = 0; i < 7; i++) {
    
    
			ch = (char)(i+'a');
			if(ch=='a'||ch=='c'||ch=='d'||ch=='f'||ch=='g') {
    
    
				notes2[j++] = getAudioClip(getCodeBase(), ch+"1s.wav");
			}
		}
		notes2[5] = getAudioClip(getCodeBase(),"c2.wav");
	}
	public void paint(Graphics g) {
    
    
		g.drawImage(keyBoard, 40, 40, 550, 200,this);
	}
	@Override
	public void start() {
    
    
		this.setLayout(null);
		int r,g,b;
		// 初始化按钮：定位+颜色+大小
		for (int i = 0; i < 17; i++) {
    
    
			btns[i]= new Button(""+(char)('a'+i));
			r= (int)(Math.random()*255);
			g= (int)(Math.random()*255);
			b= (int)(Math.random()*255);
			btns[i].setBackground(new Color(r, g, b,125));
			btns[i].setSize(32, 120);
			btns[i].setLocation(i*32+42, 42);
			add(btns[i]);
		}
		// 添加监听器
		for (int i = 0; i < 17; i++) {
    
    
			btns[i].addKeyListener(new myKeyHandler());
			btns[i].addActionListener(new myActionHandler());
		}
	}
	// 处理按键事件 => 采用多线程方法播放
	class myKeyHandler extends KeyAdapter{
    
    
		@Override
		public void keyPressed(KeyEvent e) {
    
    
			int index = e.getKeyChar()-'a';
			if(index < 0 || index > 16)
				return;
			if(index < 7) {
    
    
				new myNoteThread(notes1[index]).start();
			}else if(index < 13) {
    
    
				new myNoteThread(notes1[index-7]).start();
			}else {
    
    
				new myNoteThread(notes1[index-13]).start();
			}
			System.out.println(Thread.activeCount());
		}
	}
	// 处理鼠标点击事件  => 采用多线程方法播放
	class myActionHandler implements ActionListener
	{
    
    
		@Override
		public void actionPerformed(ActionEvent e) {
    
    
			Button btn = (Button) e.getSource();
			int index = (char)(btn.getActionCommand().toCharArray()[0]-'a'); // 0-16
			if(index < 7) {
    
    
				new myNoteThread(notes1[index]).start();
			}else if(index < 13) {
    
    
				new myNoteThread(notes1[index-7]).start();
			}else {
    
    
				new myNoteThread(notes1[index-13]).start();
			}
			System.out.println(Thread.activeCount());
		}
	}
	@Override
	public void stop() {
    
    
		// 关闭所有音乐
		for (int i = 0; i < 7; i++) {
    
    
			if(i < 6)
				notes2[i].stop();
			notes1[i].stop();
		}
	}
}
// Thread类重写
class myNoteThread extends Thread
{
    
    
	AudioClip clip;
	public myNoteThread(AudioClip cp) {
    
    
		clip = cp;
	}
	@Override
	public void run() {
    
    
		clip.play();
	}
}