[Android][Example] 用SoundPool控制左右聲道

如果需要控制左右聲道的音量，SoundPool有提供這個功能
SoundPool的優點是可以同時撥好幾個音檔
但卻對音檔的大小有限制
因此只適合撥較短的音檔

以下範例UI會有左右聲道的播放及停止按鈕

activity_main.xml

MainActivity.java

package com.qn.leftrightsound;

import android.media.AudioManager;
import android.media.SoundPool;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
    private String TAG = "leftrightsound";
    private SoundPool soundPool;
    private Button button_left_play, button_left_pause, button_right_play, button_right_pause;
    private int music_left, music_right;
    private int music_left_temp, music_right_temp;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        soundPool = new SoundPool(1, AudioManager.STREAM_MUSIC, 0);
        music_left = soundPool.load(this, R.raw.left_sound, 1);
        music_right = soundPool.load(this, R.raw.right_sound, 1);
        // 音樂檔案放在res/raw底下，預設沒有raw資料夾，要自己建

        button_left_play = (Button) findViewById(R.id.button_left_play);
        button_left_pause = (Button) findViewById(R.id.button_left_pause);
        button_right_play = (Button) findViewById(R.id.button_right_play);
        button_right_pause = (Button) findViewById(R.id.button_right_pause);

        button_left_play.setOnClickListener(ButtonListner);
        button_left_pause.setOnClickListener(ButtonListner);
        button_right_play.setOnClickListener(ButtonListner);
        button_right_pause.setOnClickListener(ButtonListner);
    }

    private Button.OnClickListener ButtonListner = new Button.OnClickListener() {

        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.button_left_play:
                Log.i(TAG, "press left play");
                music_left_temp = soundPool.play(music_left, 1, 1, 0, 0, 1);
                // 由於每次播放的id會不同，為考慮到按下暫停是要暫停剛剛播放的，因此將每次播放的id存起來
                // play()
                // 第一參數為音檔id
                // 第二.三參數為左右聲道的音量，range = 0.0 to 1.0
                // 第四參數為優先權，若不需設定可都設為0，0為最小優先權
                // 第五參數為loop，0 = no loop, -1 = loop forever
                // 第六參數為速度，1.0 = normal playback, range 0.5 to 2.0
                break;
            case R.id.button_left_pause:
                Log.i(TAG, "press left pause");
                soundPool.stop(music_left_temp);
                 break;
            case R.id.button_right_play:
                Log.i(TAG, "press right play");
                music_right_temp = soundPool.play(music_right, 0, 1, 0, 0, 1);
                break;
            case R.id.button_right_pause:
                Log.i(TAG, "press right pause");
                soundPool.stop(music_right_temp);
                break;
            }
        }
    };

    @Override
    protected void onDestroy() {
        this.soundPool.release();
         super.onPause();
    }

}