mixcanvas.java

j2me手机上的音频开发

/*
 * @(#)MixCanvas.java	1.6 04/03/10
 *
 * Copyright (c) 2000-2004 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 {
    private static final String TITLE_TEXT = "Mix Demo";
    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() {
	try {
	    if (wavPlayer == null) {
		if (MixTest.wavUrl.startsWith("resource")) {
		    int idx = MixTest.wavUrl.indexOf(':');
		    String loc = MixTest.wavUrl.substring(idx+1);
		    InputStream is = getClass().getResourceAsStream(loc);
		    String ctype = guessContentType(MixTest.wavUrl);
		    wavPlayer = Manager.createPlayer(is, ctype);
		} else {
		    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 static String guessContentType(String url) throws Exception {
	String ctype;
	// some simple test for the content type
	if (url.endsWith("wav")) {
	    ctype = "audio/x-wav";
	} else if (url.endsWith("jts")) {
	    ctype = "audio/x-tone-seq";
	} else if (url.endsWith("mid")) {
	    ctype = "audio/midi";
	} else {
	    throw new Exception("Cannot guess content type from URL: "+url);
	}
	return ctype;
    }


    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);
	    removeCommand(pauseCommand);
	    removeCommand(playCommand);
	    createWavPlayer();
	    break;

	case 1: // toneseq + tone
	    addCommand(toneCommand);
	    removeCommand(pauseCommand);
	    removeCommand(playCommand);
	    createTonePlayer();
	    break;
	case 2: // toneseq + wave
	    removeCommand(playCommand);
	    removeCommand(toneCommand);
	    addCommand(pauseCommand);
	    createWavPlayer();
	    createTonePlayer();
	    break;
	}
    }

    public void stopSound() {
	stopSound = true;
	if (tonePlayer != null) {
	    tonePlayer.close();
	    tonePlayer = null;
	}

	if (wavPlayer != null) {
	    wavPlayer.close();
	    wavPlayer = null;
	}

	removeCommand(toneCommand);
	removeCommand(pauseCommand);
	removeCommand(playCommand);
    }

    public void pauseSound() {
	removeCommand(pauseCommand);
	addCommand(playCommand);

	try {
	    if ( wavPlayer != null)
		wavPlayer.stop();
	} catch (MediaException me) {
	    System.err.println(me);
	}
	try {
	    if ( tonePlayer != null )
		tonePlayer.stop();
	} catch (MediaException me) {
	    System.err.println(me);
	}
    }

    public boolean isPlaying() {
	return ((tonePlayer != null) && (tonePlayer.getState() >= Player.STARTED))
	    || ((wavPlayer != null) && (wavPlayer.getState() >= Player.STARTED));
    }


    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(TITLE_TEXT, w/2, 8, 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);
	    }
	}
    }

}