Unity教程之-Unity5.x版本AssetBundle加载研究

之前说了 “unity4.x版本AssetBundle打包研究”,没看过的请先看一下《Unity教程之-Unity3d打包Assetbundle并加载》，再来看本文，有一定的连接性。

先梳理一下思路：
要加载一个资源A，必须先去加载它的所有依赖资源
要知道这个资源A依赖了哪些资源，必须先去加载AssetBundleManifest
通过AssetBundleManifest对象的GetAllDependencies(A)方法，获取它依赖的所有资源。
依赖资源都加载了，就可以去真正加载资源A了。

注意点：
1.资源A加载完了后，要记得Unload(false)，资源A的依赖资源要在 资源A加载完成后，才能Unload(false),否则无法正常加载资源A
2.不Unload的话也可以，那就自己做一个字典记录所有加载过的AssetBundle，还有它们的引用计数器。那样就可以先判断是否存在，然后再确定是否要去加载。

我下面的例子，采用1的方式。就是加载完了后就Unload的方式。

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;

public class AssetBundleLoaderMgr : Singleton
{
public string m_assetPath = Application.streamingAssetsPath;
string assetTail = ".unity3d" ;

#region LoadAssetBundle

///
/// 加载目标资源
///
///
///
public void LoadAssetBundle(string name, Action callback)
{
name = name + assetTail; //eg:ui/panel.unity3d

Action> action = (depenceAssetBundles) =>
{

string realName = this .GetRuntimePlatform() + "/" + name; //eg:Windows/ui/panel.unity3d

LoadResReturnWWW(realName, (www) =>
{
int index = realName.LastIndexOf( "/" );
string assetName = realName.Substring(index + 1);
assetName = assetName.Replace(assetTail, "" );
AssetBundle assetBundle = www.assetBundle;
UnityEngine.Object obj = assetBundle.LoadAsset(assetName); //LoadAsset(name）,这个name没有后缀,eg:panel

//卸载资源内存
assetBundle.Unload( false );
for ( int i = 0; i < depenceAssetBundles.Count; i++)
{
depenceAssetBundles[i].Unload( false );
}

//加载目标资源完成的回调
callback(obj);
});

};

LoadDependenceAssets(name, action);
}

///
/// 加载目标资源的依赖资源
///
///
///
private void LoadDependenceAssets(string targetAssetName, Action> action)
{
Debug.Log( "要加载的目标资源:" + targetAssetName); //ui/panel.unity3d
Action dependenceAction = (manifest) =>
{
List depenceAssetBundles = new List(); //用来存放加载出来的依赖资源的AssetBundle

string[] dependences = manifest.GetAllDependencies(targetAssetName);
Debug.Log( "依赖文件个数：" + dependences.Length);
int length = dependences.Length;
int finishedCount = 0;
if (length == 0)
{
//没有依赖
action(depenceAssetBundles);
}
else
{
//有依赖，加载所有依赖资源
for ( int i = 0; i < length; i++)
{
string dependenceAssetName = dependences[i];
dependenceAssetName = GetRuntimePlatform() + "/" + dependenceAssetName; //eg:Windows/altas/heroiconatlas.unity3d

//加载，加到assetpool
LoadResReturnWWW(dependenceAssetName, (www) =>
{
int index = dependenceAssetName.LastIndexOf( "/" );
string assetName = dependenceAssetName.Substring(index + 1);
assetName = assetName.Replace(assetTail, "" );
AssetBundle assetBundle = www.assetBundle;
UnityEngine.Object obj = assetBundle.LoadAsset(assetName);
//assetBundle.Unload(false);
depenceAssetBundles.Add(assetBundle);

finishedCount++;

if (finishedCount == length)
{
//依赖都加载完了
action(depenceAssetBundles);
}
});
}
}
};
LoadAssetBundleManifest(dependenceAction);
}

///
/// 加载AssetBundleManifest
///
///
private void LoadAssetBundleManifest(Action action)
{
string manifestName = this .GetRuntimePlatform();
manifestName = manifestName + "/" + manifestName; //eg:Windows/Windows
LoadResReturnWWW(manifestName, (www) =>
{
AssetBundle assetBundle = www.assetBundle;
UnityEngine.Object obj = assetBundle.LoadAsset( "AssetBundleManifest" );
assetBundle.Unload( false );
AssetBundleManifest manif = obj as AssetBundleManifest;
action(manif);
});
}
#endregion

#region ExcuteLoader
public void LoadResReturnWWW(string name, Action callback)
{
string path = "file://" + this .m_assetPath + "/" + name;
Debug.Log( "加载：" + path);
StartCoroutine(LoaderRes(path, callback));
}

IEnumerator LoaderRes(string path, Action callback)
{
WWW www = new WWW(path);
yield return www;
if (www.isDone)
{
callback(www);
}
}
#endregion

#region Util
///
/// 平台对应文件夹
///
///
private string GetRuntimePlatform()
{
string platform = "" ;
if (Application.platform == RuntimePlatform.WindowsPlayer || Application.platform == RuntimePlatform.WindowsEditor)
{
platform = "Windows" ;
}
else if (Application.platform == RuntimePlatform.Android)
{
platform = "Android" ;
}
else if (Application.platform == RuntimePlatform.IPhonePlayer)
{
platform = "IOS" ;
}
else if (Application.platform == RuntimePlatform.OSXPlayer || Application.platform == RuntimePlatform.OSXEditor)
{
platform = "OSX" ;
}
return platform;
}
}

测试一下咯

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class TestAssetBundleLoader : MonoBehaviour
{
Dictionary GameObjectPool = new Dictionary();

void Start()
{
//要加载的资源的队列
Queue needLoadQueue = new Queue();
needLoadQueue.Enqueue( "ui/plane" );
needLoadQueue.Enqueue( "ui/cube" );
needLoadQueue.Enqueue( "ui/sphere" );

Load(needLoadQueue);
}

void Load(Queue needLoadQueue)
{
if (needLoadQueue.Count > 0)
{
string needLoadAssetName = needLoadQueue.Dequeue();
AssetBundleLoaderMgr.Instance.LoadAssetBundle(needLoadAssetName, (obj) =>
{
GameObject go = GameObject.Instantiate(obj) as GameObject;
int index = needLoadAssetName.LastIndexOf( "/" );
string assetName = needLoadAssetName.Substring(index + 1);

//加载出来的GameObject放到GameObjectPool存储
GameObjectPool.Add(assetName, go);

Load(needLoadQueue);
});
}
else
{
Debug.Log( "all finished" );
}
}
}

可能代码写的还有很多优化的地方 ,毕竟100个人有100种写法，思路才是最重要的。你说呢？
其实我想说的是，代码都在了，自己尝试一下吧！好了，本篇unity3d教程到此结束，下篇我们再会！