【读书笔记《Android游戏编程之从零开始》】19.游戏开发基础（游戏音乐与音效）

package com.example.ex4_16;

import java.io.IOException;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class MySurfaceView extends SurfaceView implements Callback, Runnable,
        OnCompletionListener {
    private SurfaceHolder sfh;
    private Paint paint;
    private Thread th;
    private boolean flag;
    private Canvas canvas;
    private int screenW, screenH;
    // 声明音乐的状态常量
    private final int MEDIAPLAYER_PAUSE = 0;// 暂停
    private final int MEDIAPLAYER_PLAY = 1;// 播放中
    private final int MEDIAPLAYER_STOP = 2;// 停止
    // 音乐的当前的状态
    private int mediaSate = 0;
    // 声明一个音乐播放器
    private MediaPlayer mediaPlayer;
    // 当前音乐播放的时间点
    private int currentTime;
    // 当前音乐的总时间
    private int musicMaxTime;
    // 当前音乐的音量大小
    private int currentVol;
    // 快进、快退时间戳
    private int setTime = 5000;
    // 播放器管理类
    private AudioManager am;

    public MySurfaceView(Context context) {
        super(context);
        sfh = this.getHolder();
        sfh.addCallback(this);
        paint = new Paint();
        paint.setColor(Color.WHITE);
        paint.setAntiAlias(true);
        setFocusable(true);
        // 实例音乐播放器
        mediaPlayer = MediaPlayer.create(context, R.raw.bgmusic);
        // 设置循环播放(设置了循环，“OnCompletionListener”监听器无法监听音乐是否播放完成)
        // mediaPlayer.setLooping(true);//设置循环播放
        // 获取音乐文件的总时间
        musicMaxTime = mediaPlayer.getDuration();
        // 实例管理类
        am = (AudioManager) MainActivity.instance
                .getSystemService(Context.AUDIO_SERVICE);
        // 设置当前调整音量大小只是针对媒体音乐进行调整
        MainActivity.instance.setVolumeControlStream(AudioManager.STREAM_MUSIC);
        // 绑定音乐完成监听器
        mediaPlayer.setOnCompletionListener(this);
    }

    /**
     * SurfaceView视图创建，响应此函数
     */
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        screenW = this.getWidth();
        screenH = this.getHeight();
        flag = true;
        // 实例线程
        th = new Thread(this);
        // 启动线程
        th.start();
    }

    /**
     * 游戏绘图
     */
    public void myDraw() {
        try {
            canvas = sfh.lockCanvas();
            if (canvas != null) {
                canvas.drawColor(Color.WHITE);
                paint.setColor(Color.RED);
                paint.setTextSize(15);
                canvas.drawText("当前音量: " + currentVol, 50, 40, paint);
                canvas.drawText("当前播放的时间/总时间", 50, 70, paint);
                canvas.drawText(toTime(currentTime) + "/" + toTime(musicMaxTime), 100, 100,
                        paint);
                canvas.drawText("方向键中间按钮切换 暂停/开始", 50, 130, paint);
                canvas.drawText("方向键←键快退" + setTime / 1000 + "秒 ", 50, 160,
                        paint);
                canvas.drawText("方向键→键快进" + setTime / 1000 + "秒 ", 50, 190,
                        paint);
                canvas.drawText("方向键↑键增加音量 ", 50, 220, paint);
                canvas.drawText("方向键↓键减小音量", 50, 250, paint);
            }
        } catch (Exception e) {
            // TODO: handle exception
        } finally {
            if (canvas != null)
                sfh.unlockCanvasAndPost(canvas);
        }
    }

    /**
     * 触屏事件监听
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return true;
    }

    /**
     * 按键事件监听
     */
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // 导航中键播放/暂停操作
        if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
            try {
                switch (mediaSate) {
                // 当前处于播放的状态
                case MEDIAPLAYER_PLAY:
                    mediaPlayer.pause();
                    mediaSate = MEDIAPLAYER_PAUSE;
                    break;
                // 当前处于暂停的状态
                case MEDIAPLAYER_PAUSE:
                    mediaPlayer.start();
                    mediaSate = MEDIAPLAYER_PLAY;
                    break;
                // 当前处于停止的状态
                case MEDIAPLAYER_STOP:
                    /*
                     * 使用android MediaPlayer播放一段音乐时，有时会出现prepareasync called in
                     * state 8错误。 以下方法可以避免这个异常出现,
                     * //在播放之前先判断playerMusic是否被占用，这样就不会报错了
                     */
                    if (mediaPlayer != null) {
                        mediaPlayer.pause();
                        mediaPlayer.stop();
                    }
                    mediaPlayer.prepare();
                    mediaPlayer.start();
                    mediaSate = MEDIAPLAYER_PLAY;
                    break;
                }
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            // 导航上键调整音乐播放声音变大
        } else if (keyCode == KeyEvent.KEYCODE_DPAD_UP) {
            am.setStreamVolume(AudioManager.STREAM_MUSIC, currentVol + 1,
                    AudioManager.FLAG_PLAY_SOUND);
            // 导航下键调整音乐播放声音变小
        } else if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
            am.setStreamVolume(AudioManager.STREAM_MUSIC, currentVol - 1,
                    AudioManager.FLAG_PLAY_SOUND);
            // 导航左键调整音乐播放时间倒退五秒
        } else if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
            if (currentTime - setTime <= 0) {
                mediaPlayer.seekTo(0);
            } else {
                mediaPlayer.seekTo(currentTime - setTime);
            }
            // 导航右键调整音乐播放时间快进五秒
        } else if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) {
            if (currentTime + setTime >= musicMaxTime) {
                mediaPlayer.seekTo(musicMaxTime);
            } else {
                mediaPlayer.seekTo(currentTime + setTime);
            }
        }
        return super.onKeyDown(keyCode, event);
    }

    /**
     * 游戏逻辑
     */
    private void logic() {
        if (mediaPlayer != null) {
            // 获取当前音乐播放的时间
            currentTime = mediaPlayer.getCurrentPosition();
            // 获取当前的音量值
            currentVol = am.getStreamVolume(AudioManager.STREAM_MUSIC);
            // 获取当前的音量最大值
            // int valueMax = am.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
        } else {
            currentTime = 0;
        }
    }

    /**
     * SurfaceView视图状态发生改变，响应此函数
     */
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {

    }

    /**
     * SurfaceView视图消亡时，响应此函数
     */
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        flag = false;
        if (mediaPlayer != null) {
            mediaPlayer.stop();
        }
    }

    /**
     * 作用：音乐播放完毕会响应此函数
     * 参数：完成音乐播放的MediaPlayer 实例
     * 这个监听播放是否完成的监听器，只能针对音乐只播放一次的情况进行监听。如果设置了音乐循环，那么监听器永远都不会监听到音乐是否播放完成！
     */
    @Override
    public void onCompletion(MediaPlayer arg0) {
        if (mediaPlayer == arg0) {
            Log.v("Log---------", "Play Completed");
        }
    }

    @Override
    public void run() {
        while (flag) {
            long start = System.currentTimeMillis();
            myDraw();
            logic();
            long end = System.currentTimeMillis();
            try {
                if (end - start < 50) {
                    Thread.sleep(50 - (end - start));
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    /**
     * 播放器进度条时间处理方法
     * 
     * @param time
     * @return
     */
    public String toTime(int time) {

        time /= 1000;
        int minute = time / 60;
        int second = time % 60;
        minute %= 60;
        return String.format("%02d:%02d", minute, second);
    }
}

package com.example.ex4_17;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.media.AudioManager;
import android.media.SoundPool;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class MySurfaceView extends SurfaceView implements Callback, Runnable {
    private SurfaceHolder sfh;
    private Paint paint;
    private Thread th;
    private boolean flag;
    private Canvas canvas;
    // 声明SoundPool
    private SoundPool sp;
    // 记录长音乐文件id
    private int soundId_long;
    // 记录断短音乐文件id
    private int soundId_short;

    /**
     * SurfaceView初始化函数
     */
    public MySurfaceView(Context context) {
        super(context);
        sfh = this.getHolder();
        sfh.addCallback(this);
        paint = new Paint();
        paint.setColor(Color.WHITE);
        paint.setAntiAlias(true);
        setFocusable(true);
        // 实例SoundPool播放器
        sp = new SoundPool(4, AudioManager.STREAM_MUSIC, 100);
        // 加载音乐文件获取其数据ID
        soundId_long = sp.load(context, R.raw.song_long, 1);
        // 加载音乐文件获取其数据ID
        soundId_short = sp.load(context, R.raw.song_short, 1);
    }

    /**
     * SurfaceView视图创建，响应此函数
     */
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        flag = true;
        // 实例线程
        th = new Thread(this);
        // 启动线程
        th.start();
    }

    /**
     * 游戏绘图
     */
    public void myDraw() {
        try {
            canvas = sfh.lockCanvas();
            if (canvas != null) {
                canvas.drawColor(Color.WHITE);
                paint.setColor(Color.RED);
                paint.setTextSize(15);
                canvas.drawText("点击导航键的上键：播放断音效", 50, 50, paint);
                canvas.drawText("点击导航键的下键：播放长音效", 50, 80, paint);
            }
        } catch (Exception e) {
            // TODO: handle exception
        } finally {
            if (canvas != null)
                sfh.unlockCanvasAndPost(canvas);
        }
    }

    /**
     * 触屏事件监听
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return true;
    }

    /**
     * 按键事件监听
     */    
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        //导航键的上键
        if (keyCode == KeyEvent.KEYCODE_DPAD_UP)
            sp.play(soundId_short, 2, 2, 0, 0, 1);//播放音乐
        //导航键的下键
        else if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN)
            sp.play(soundId_long, 1f, 1f, 0, 0, 1);
        return super.onKeyDown(keyCode, event);
    }

    /**
     * 游戏逻辑
     */
    private void logic() {
    }

    /**
     * SurfaceView视图状态发生改变，响应此函数
     */
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {

    }

    /**
     * SurfaceView视图消亡时，响应此函数
     */
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        flag = false;
    }

    @Override
    public void run() {
        while (flag) {
            long start = System.currentTimeMillis();
            myDraw();
            logic();
            long end = System.currentTimeMillis();
            try {
                if (end - start < 50) {
                    Thread.sleep(50 - (end - start));
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}