J2ME Study—播放简单音调示例(10)

    使用MIDP发出一个简单的音调非常简单，只需使用 Manager 类的静态方法 playTone 就可以完成。方法的定义如下：
    public static void playTone(int note, int duration, int volume)
    note表示单音符，取值范围0~127
    duration表示持续播放此音符的时间
    volume表示音量，范围是0~100

    在本示例中，给出一个简单的实例，说明简单音调的播放方法。下面是程序源码：

package zieckey.j2me.study.mmapi;

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Gauge;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
import javax.microedition.media.Manager;

/**
 *
 * 本程序给出播放简单音调的示例。
 *
 * 在程序界面上放置了音调和音量的控制，这是通过Gauge控件完成的。
 * 另外，还可以通过一个TextField控件实现播放时间的控制。
 *
 * @author zieckey
 * @version 2008.4.26
 *
 */
public class PlayToneMIDlet extends MIDlet implements CommandListener
{
    private Display        display;
    private Command        playCommand;
    private Command        exitCommand;
    private Form        form;
    private Gauge        noteGauge;
    private Gauge        volumeGauge;
    private TextField    durationTextField;

    public PlayToneMIDlet( )
    {
        display = Display.getDisplay( this );
        playCommand = new Command( "播放", Command.SCREEN, 1 );
        exitCommand = new Command( "退出", Command.SCREEN, 1 );
        

        form = new Form( "播放音调示例" );
        
        //Gauge(String label, boolean interactive, int maxValue, int initialValue)
        noteGauge = new Gauge( "音调", true, 127, 60 );
        volumeGauge = new Gauge( "音量", true, 100, 63 );
        durationTextField = new TextField( "持续时间", "1000", 10, TextField.NUMERIC );

        form.append( noteGauge );
        form.append( volumeGauge );
        form.append( durationTextField );
        form.addCommand( playCommand );
        form.addCommand( exitCommand );
        form.setCommandListener( this );
    }

    protected void startApp() throws MIDletStateChangeException
    {
        display.setCurrent( form );
    }

    protected void destroyApp( boolean arg0 ) throws MIDletStateChangeException
    {

    }

    protected void pauseApp()
    {

    }

    public void commandAction( Command cmd, Displayable d )
    {
        // 对该命令的响应

        if ( cmd == exitCommand )
        {
            try
            {
                destroyApp( true );
            } catch ( MIDletStateChangeException e )
            {
                e.printStackTrace();
            }
            notifyDestroyed();
        } else if ( cmd == playCommand )
        {
            try
            {
                /**
                 * Player的VolumeControl数值为0~100
                 *
                 * note表示单音符，取值范围0~127
                 * duration表示持续播放此音符的时间
                 * volume表示音量，范围是0~100
                 * Manager.playTone(int note, int duration, int volume)
                 */
                Manager.playTone( noteGauge.getValue(),
                        Integer.parseInt( durationTextField.getString() ),
                        volumeGauge.getValue() );
            } catch ( Exception e )
            {
                e.printStackTrace();
            }
        }

    }

}