chap12-9.txt

JAVA 学习资源

// 程序12-9
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class playAudio extends JApplet {    
    AudioClip sound1, sound2, currentSound;  
    JButton playSound, loopSound, stopSound;
    JComboBox choose;
   
    public void init( ){    // 初始化各对象   
        Container container = getContentPane( );   // 获取内容格 
        container.setLayout( new FlowLayout( ) );  // 设置布局  

        String choices[ ] = { "Welcome", "Hi" };   // 下拉列表的选项
        choose = new JComboBox( choices );     // 定义一个下拉列表   

        choose.addItemListener(        	// 定义一个匿名类，实现选择监听
            new ItemListener( ) {                
                    // 若重新选择声音文件，将停止当前播放，启动新选的声音剪辑
                public void itemStateChanged( ItemEvent e ) {
                    currentSound.stop( );   	// 停止当前播放的声音剪辑               
                        // 确定新选的声音剪辑
                    currentSound = choose.getSelectedIndex( ) == 0 ? sound1 : sound2;
                }
            }
        ); 

        container.add( choose );      // 将组件choose加入到容器中

            // 定义按钮对象，并设置事件监听者
        ButtonHandler handler = new ButtonHandler( );
      
        playSound = new JButton( "Play" );
        playSound.addActionListener( handler );
        container.add( playSound );

        loopSound = new JButton( "Loop" );
        loopSound.addActionListener( handler );
        container.add( loopSound );

        stopSound = new JButton( "Stop" );
        stopSound.addActionListener( handler );
        container.add( stopSound );

            // 载入声音剪辑，并对currentSound初始化
        sound1 = getAudioClip( getDocumentBase( ), "welcome.wav" );
        sound2 = getAudioClip( getDocumentBase( ), "hi.au" );
        currentSound = sound1;
    }  

        // 当用户单击stop按钮时，终止播放声音剪辑
    public void stop( ) {
        currentSound.stop( );
    }

        // 定义一个内部类，处理按钮事件
    private class ButtonHandler implements ActionListener { 
            // 处理 play，loop和stop 按钮事件
        public void actionPerformed( ActionEvent actionEvent ){
            if ( actionEvent.getSource( ) == playSound ) 
                currentSound.play( );
            else if ( actionEvent.getSource( ) == loopSound ) 
                currentSound.loop( );
            else if ( actionEvent.getSource( ) == stopSound ) 
                currentSound.stop( );
        }
    }
}