读 Beginning Android Games 2nd Edition (二) 创建声音工具类

在Andorid中有三类声音文件,一种是存放在Asset文件夹中的音频文件称为Audio,一种是音效文件(一般为游戏需要,像是击打声之类比较短暂的声音)称为Sound,一种是文件容量比较大的音乐文件,一般是存在手机内存或SD卡中,称之为Music

下面是分类实现

Audio类接口和实现

package com.badlogic.androidgames.framework;

public interface Audio {
    public Music newMusic(String filename);

    public Sound newSound(String filename);
}

package com.badlogic.androidgames.framework.impl;

import java.io.IOException;

import android.app.Activity;
import android.content.res.AssetFileDescriptor;
import android.content.res.AssetManager;
import android.media.AudioManager;
import android.media.SoundPool;

import com.badlogic.androidgames.framework.Audio;
import com.badlogic.androidgames.framework.Music;
import com.badlogic.androidgames.framework.Sound;

public class AndroidAudio implements Audio {
    AssetManager assets;
    SoundPool soundPool;

    public AndroidAudio(Activity activity) {
        activity.setVolumeControlStream(AudioManager.STREAM_MUSIC);
        this.assets = activity.getAssets();
        this.soundPool = new SoundPool(20, AudioManager.STREAM_MUSIC, 0);
    }

    public Music newMusic(String filename) {
        try {
            AssetFileDescriptor assetDescriptor = assets.openFd(filename);
            return new AndroidMusic(assetDescriptor);
        } catch (IOException e) {
            throw new RuntimeException("Couldn't load music '" + filename + "'");
        }
    }
    
    public Sound newSound(String filename) {
        try {
            AssetFileDescriptor assetDescriptor = assets.openFd(filename);
            int soundId = soundPool.load(assetDescriptor, 0);
            return new AndroidSound(soundPool, soundId);
        } catch (IOException e) {
            throw new RuntimeException("Couldn't load sound '" + filename + "'");
        }
    }
}

Sound类接口和实现

package com.badlogic.androidgames.framework;

public interface Sound {
    public void play(float volume);

    public void dispose();
}

package com.badlogic.androidgames.framework.impl;

import android.media.SoundPool;

import com.badlogic.androidgames.framework.Sound;

public class AndroidSound implements Sound {
    int soundId;
    SoundPool soundPool;

    public AndroidSound(SoundPool soundPool, int soundId) {
        this.soundId = soundId;
        this.soundPool = soundPool;
    }

    public void play(float volume) {
        soundPool.play(soundId, volume, volume, 0, 0, 1);
    }

    public void dispose() {
        soundPool.unload(soundId);
    }
}

Music类接口和实现

package com.badlogic.androidgames.framework;

public interface Music {
    public void play();

    public void stop();

    public void pause();

    public void setLooping(boolean looping);

    public void setVolume(float volume);

    public boolean isPlaying();

    public boolean isStopped();

    public boolean isLooping();

    public void dispose();
}

package com.badlogic.androidgames.framework.impl;

import java.io.IOException;

import android.content.res.AssetFileDescriptor;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;

import com.badlogic.androidgames.framework.Music;

public class AndroidMusic implements Music, OnCompletionListener {
    MediaPlayer mediaPlayer;
    boolean isPrepared = false;

    public AndroidMusic(AssetFileDescriptor assetDescriptor) {
        mediaPlayer = new MediaPlayer();
        try {
            mediaPlayer.setDataSource(assetDescriptor.getFileDescriptor(),
                    assetDescriptor.getStartOffset(),
                    assetDescriptor.getLength());
            mediaPlayer.prepare();
            isPrepared = true;
            mediaPlayer.setOnCompletionListener(this);
        } catch (Exception e) {
            throw new RuntimeException("Couldn't load music");
        }
    }

    public void dispose() {
        if (mediaPlayer.isPlaying())
            mediaPlayer.stop();
        mediaPlayer.release();
    }
    
    public boolean isLooping() {
        return mediaPlayer.isLooping();
    }

    public boolean isPlaying() {
        return mediaPlayer.isPlaying();
    }

    public boolean isStopped() {
        return !isPrepared;
    }
    
    public void pause() {
        if (mediaPlayer.isPlaying())
            mediaPlayer.pause();
    }
    
    public void play() {
        if (mediaPlayer.isPlaying())
            return;
        try {
            synchronized (this) {
                if (!isPrepared)
                    mediaPlayer.prepare();
                mediaPlayer.start();
            }
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void setLooping(boolean isLooping) {
        mediaPlayer.setLooping(isLooping);
    }

    public void setVolume(float volume) {
        mediaPlayer.setVolume(volume, volume);
    }
    
    public void stop() {
        mediaPlayer.stop();
        synchronized (this) {
            isPrepared = false;
        }
    }

    public void onCompletion(MediaPlayer player) {
        synchronized (this) {
            isPrepared = false;
        }
    }
}