遊戲中有很多東西是需要預載入進來的，這樣可以使遊戲更流暢，雖然，遊戲中音效佔用的資源比較少，但是，還是有必要為音效做一個預載入的，這裡用安卓原生的方法實現了一個音效載入系統。

思路：

安卓中游戲的資源通常都是根據id來載入的（這個id可以在R.java檔案中找到），在系統中使用了兩個HashMap,一個儲存資源的ID，一個儲存音效載入後的ID，這兩個HashMap有共同的key值將兩個表聯絡起來。

系統中實現了資源的載入，根據資源ID播放音效，解除安裝資源。

下面是腦圖的地址，是系統中詳細函式的介紹。

http://naotu.baidu.com/file/079133fa68a2e51d5800f905e77ef67b?token=d52654a7a8883f62

Demo程式碼：

MainActivity.java

package com.example.soundloadsystem;

import android.R.integer;
import android.app.Activity;
import android.content.Context;
import android.media.AudioManager;
import android.media.SoundPool;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
	public static MainActivity _instance ;
	public SoundLoadSystem soundLoadSystem;
	public SoundPool m_soundPool ;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		//setContentView(R.layout.activity_main);
		setContentView(R.layout.main);
		_instance = this;
		m_soundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, 0);
		soundLoadSystem = SoundLoadSystem.Instance();
		addSoundRes();
		initUICallback();
	}

	public void addSoundRes()
	{
		soundLoadSystem.add(R.raw.sound_0);
		soundLoadSystem.add(R.raw.sound_1);
		soundLoadSystem.add(R.raw.sound_2);
		soundLoadSystem.add(R.raw.sound_3);
		soundLoadSystem.add(R.raw.sound_4);
		soundLoadSystem.add(R.raw.sound_5);
	}
	
	public void initUICallback()
	{
		Button btn1 = (Button)findViewById(R.id.Button01);
		Button btn2 = (Button)findViewById(R.id.Button02);
		Button btn3 = (Button)findViewById(R.id.Button04);
		btn1.setOnClickListener(
				new OnClickListener() {
					
					@Override
					public void onClick(View v) {
						// TODO Auto-generated method stub
						soundLoadSystem.load();
					}
				}
				);
		btn2.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub\
				AudioManager am = (AudioManager)_instance.getSystemService(Context.AUDIO_SERVICE);
				float streamVolumeCurrent = am.getStreamVolume(AudioManager.STREAM_MUSIC);
				float streamVolumeMax = am.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
				
				float volume = streamVolumeCurrent / streamVolumeMax;
				
				m_soundPool.play(soundLoadSystem.getRandomID(), volume, volume, 1, 0, 1.0f);
			}
		});
		
		btn3.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				soundLoadSystem.unload();
			}
		});
	}
}
 

package com.example.soundloadsystem;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Random;

import android.R.integer;
import android.content.Context;
import android.drm.DrmStore.RightsStatus;
import android.media.AudioManager;
import android.media.SoundPool;
import android.util.Log;

public class SoundLoadSystem 
{
	public static SoundLoadSystem _instance ;
	public HashMap<Integer, Integer> m_soundResIDMap ;
	public HashMap<Integer, Integer> m_soundIDMap;
	public int m_index = 0 ;
	public static SoundLoadSystem Instance()
	{
		if (_instance == null) {
			_instance = new SoundLoadSystem();
		}
		return _instance ;
	}
	public static void Destory()
	{
		_instance = null ;
		System.gc();
	}
	private SoundLoadSystem() {
		// TODO Auto-generated constructor stub
		m_soundResIDMap = new HashMap<Integer, Integer>();
		m_soundIDMap = new HashMap<Integer, Integer>();
	}
	public void add(Integer id)
	{
		if (isHave(id) == false) {
			m_soundResIDMap.put(m_index, id);
			m_index++ ;
		}
	}
	public void load()
	{
		Context cot = MainActivity._instance ;
		SoundPool spPool = MainActivity._instance.m_soundPool;
		int per = 0 ;
		Iterator iterator = m_soundResIDMap.entrySet().iterator() ;
		while (iterator.hasNext()) {
			Map.Entry<Integer,Integer> entry = (Map.Entry<Integer,Integer>)iterator.next();
			Integer index = entry.getKey();
			Integer id = entry.getValue();
			Integer spID = spPool.load(cot, id,1);
			m_soundIDMap.put(index, spID);
			per++;
		}
	}
	public int getLength()
	{
		//Because m_index start from 0,so the length is m_index + 1.
		return m_soundIDMap.size();
	}
	public boolean isHave(Integer id)
	{
		return m_soundResIDMap.containsValue(id) ;
	}
	public Integer getRandomID()
	{
		if (m_soundIDMap.size() == 0
			|| m_soundResIDMap.size() == 0	) 
		{
			Log.e("load_error","Doesn't load any res.");
			return -1;
		}
		Integer ret = -1;
		Random random = new Random();
		Integer randInteger = random.nextInt(getLength());
		ret = m_soundIDMap.get(randInteger);
		return ret;
	}
	
	public void unload()
	{
		SoundPool spPool = MainActivity._instance.m_soundPool;
		spPool.unload(1);
		Iterator iterator = m_soundIDMap.entrySet().iterator() ;
		while (iterator.hasNext()) {
			Map.Entry<Integer,Integer> entry = (Map.Entry)iterator.next();
			Integer id = entry.getValue();
			spPool.unload(id);
		}
		m_soundIDMap.clear();
		m_soundIDMap = new HashMap<Integer, Integer>();
	}
	
	public int getSoundIDByResID(Integer resID)
	{
		int soundID = -1;
		int index = -1;
		boolean isHave = m_soundResIDMap.containsKey(resID);
		if (isHave) {
			Iterator iterator = m_soundIDMap.entrySet().iterator() ;
			while (iterator.hasNext()) {
				Map.Entry<Integer,Integer> entry = (Map.Entry)iterator.next();
				Integer idx = entry.getKey();
				Integer id = entry.getValue();
				if (id == resID) {
					index = idx ;
				}
			}
			soundID = m_soundIDMap.get(index);
		}
		else {
			Log.e("sound_res","can't find sound which id is" + resID);
		}
		return soundID ;
	}
	public void reset()
	{
		m_soundIDMap.clear();
		m_soundResIDMap.clear();
		m_soundIDMap = new HashMap<Integer, Integer>();
		m_soundResIDMap = new HashMap<Integer, Integer>();
		m_index = 0;
	}
}