mixcanvas.java

mp3播放程序

/*
 * @(#)MixCanvas.java	1.10 02/08/15 @(#)
 *
 * Copyright (c) 2001-2002 Sun Microsystems, Inc.  All rights reserved.
 * PROPRIETARY/CONFIDENTIAL
 * Use is subject to license terms.
 */

package example.audiodemo;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.media.*;
import javax.microedition.media.control.*;

import java.io.*;

public class MixCanvas extends Canvas implements CommandListener, Runnable {
    private static final String TITLE_TEXT = "audio player";
    private static final int[]  notes = {69, 70,71,72,73,74, 75, 76};
    static Player  wavPlayer = null, tonePlayer = null;

    static Image logo = null;
    private int idx = 0, ip =0;

    Display parentDisplay;
    private Command     backCommand       = new Command("Back", Command.BACK,
                                                1);
    private Command     playCommand       = new Command("Play",
                                                Command.ITEM, 1);
    private Command     pauseCommand      = new Command("Pause",
                                                Command.ITEM, 1);

    private Command     toneCommand       = new Command("Tone",
						Command.ITEM, 1);
    
    private Alert alert;
	
	//In case the user ended the player using the back command
	//or the 'End' button (the red one), if the WavPlayer did not
	//start yet there is a possibility that it will start after a while.
	//stopSound is here to catch this case and avoid playing the sound.
	private boolean stopSound = false;

    public MixCanvas(Display parentDisplay) {
        super();
		this.idx = 0;
		this.parentDisplay = parentDisplay;
		initialize();
    }

    void initialize() {
        addCommand(backCommand);
        setCommandListener(this);

		try {
			logo = Image.createImage("/icons/logo.png");
		} catch (Exception ex) {
			logo = null;
		}
		if ( logo == null) {
			System.out.println("can not load logo.png");
		}
		alert = new Alert("Warning", "Can not create player", null, null);
		alert.setTimeout(1000);
    }

    /*
     * Respond to commands, including back
     */
    public void commandAction(Command c, Displayable s) {

        if (s == this) {
            if (c == backCommand) {
                stopSound();
                parentDisplay.setCurrent(MixTest.getList());
			} else if ( c == toneCommand ) {
				try {
					Manager.playTone(notes[ip], 1000, 100);
					ip++;
					if ( ip >= 8 )
					ip = 0;
				} catch (Exception ex) {
					System.out.println("get an exception for tone");
				}
			} else if (c == playCommand) {
				playSound();
			} else if (c == pauseCommand) {
				pauseSound();
			}
		}
    }

    public void setIndex(int idx) {
		this.idx = idx;
    }

    private void createWavPlayer() {		
		// method createWavPlayer() runs on GUI thread. Manager.createPlayer()
		// will potentially invoke a blocking I/O. This is not the good
		// practice recommonded by MIDP programming style. So here we
		// will create the Player in a separate thread.
		new Thread(this).start();
    } 

    public void run() {
		try {
			if (wavPlayer == null) {
			wavPlayer = Manager.createPlayer(MixTest.wavUrl);
			wavPlayer.setLoopCount(-1);
			}
			if(stopSound) {
				return;
			}
			wavPlayer.start();
		} catch (Exception ex) {
			// ex.printStackTrace();
			if (wavPlayer != null) {
			wavPlayer.close();
			wavPlayer = null;
			}
			parentDisplay.setCurrent(alert);
		}
    }

    private void createTonePlayer() {
		
		byte d = 8; 
		byte C4 = ToneControl.C4;
		byte D4 = ToneControl.C4 + 2; // a whole step 
		byte E4 = ToneControl.C4 + 4; // a major third
		byte G4 = ToneControl.C4 + 7; // a fifth
		byte rest = ToneControl.SILENCE; // eighth-note rest
				
		byte[] mySequence = new byte[] {
			ToneControl.VERSION, 1,
			ToneControl.TEMPO, 30,
			ToneControl.BLOCK_START, 0,
			E4,d,D4,d,C4,d,D4,d,E4,d,E4,d,E4,d,rest,d, 
			ToneControl.BLOCK_END,0,
			ToneControl.PLAY_BLOCK,0,
			D4,d,D4,d,D4,d,rest,d,E4,d,G4,d,G4,d,rest,d,//play "B" section 
			ToneControl.PLAY_BLOCK,0, // content of "A" section 
			D4,d,D4,d,E4,d,D4,d,C4,d,rest,d// play "C" section 
		};
		
		try {
			if ( tonePlayer == null) {
			tonePlayer = Manager.createPlayer(Manager.TONE_DEVICE_LOCATOR);
			tonePlayer.setLoopCount(-1);
			tonePlayer.realize();
			ToneControl tc = (ToneControl)tonePlayer.getControl("javax.microedition.media.control.ToneControl");
			tc.setSequence(mySequence);
			}
			if ( tonePlayer != null && !stopSound) {
				tonePlayer.start();
			}
		} catch (Exception ex) {
			// ex.printStackTrace();
			if (tonePlayer != null) {
				tonePlayer.close();
				tonePlayer = null;
			}
			parentDisplay.setCurrent(alert);
		}
    }

    public void playSound() {
		stopSound = false;
		switch(idx) {
			case 0: // wave + tone
				addCommand(toneCommand);
				createWavPlayer();
				break;
				
			case 1: // toneseq + tone
				addCommand(toneCommand);
				createTonePlayer();
				break;
			case 2: 
				removeCommand(playCommand);
				addCommand(pauseCommand);
				createWavPlayer();		
				createTonePlayer();
				break;
		}
    }

    public void stopSound() {
		stopSound = true;
		if (tonePlayer != null) {
			tonePlayer.close();
			tonePlayer = null;
		}
	
		if (wavPlayer != null) {
			wavPlayer.close();
			wavPlayer = null;
		}
		
		switch(idx) {
			case 0:
			case 1:
				removeCommand(toneCommand);
				break;
			case 2:
				removeCommand(pauseCommand);
				removeCommand(playCommand);
				break;
		}
    }
    
    public void pauseSound() {
		removeCommand(pauseCommand);
		addCommand(playCommand);

		try {
			if ( wavPlayer != null) 
				wavPlayer.stop();

			if ( tonePlayer != null )
				tonePlayer.stop();
		} catch (MediaException e) {
			// Nothing much to do here.
		}
    }

    
    public void paint(Graphics g) {
		int w = getWidth();
		int h = getHeight();
		String cname = "";

		switch(idx) {
		case 0:
			cname = "test-wav.wav";
			break;
		case 1:
			cname = "tone seq";
			break;
		case 2:
			cname = "wave+toneseq";
			break;
		}

		g.setColor(0);
		g.fillRect(0, 0, w, h);
	
		if ( logo != null ) {
			g.drawImage(logo, w/2, 30, Graphics.TOP | Graphics.HCENTER);
		}
		g.setColor(0xFF7f00);
		g.drawString("audio Player", w/2, 8, Graphics.TOP | Graphics.HCENTER);
		//g.drawString("audio player!", w/2, 64, Graphics.TOP | Graphics.HCENTER);
		g.drawString(cname, 0, 84, Graphics.TOP | Graphics.LEFT);

    }

    protected void keyPressed(int keycode) {
		switch (keycode) {
		case KEY_STAR:
			changeVolume(-10);
			break;
		case KEY_POUND:
			changeVolume(10);
			break;
		}
    }

    private void changeVolume(int diff) {
		VolumeControl vc;
	
		if ( wavPlayer != null) {
			vc = (VolumeControl) wavPlayer.getControl("VolumeControl");
			if (vc != null) {
			int cv = vc.getLevel();
			cv += diff;
			cv = vc.setLevel(cv);
			}
		}
	
		if ( tonePlayer != null) {
			vc = (VolumeControl) tonePlayer.getControl("VolumeControl");
			if (vc != null) {
			int cv = vc.getLevel();
			cv += diff;
			cv = vc.setLevel(cv);
			}
		}
    }

}