unity创建和加载AssetBundle

先说一下为什么要使用AssetBundle吧，以前做东西一直忽略这个问题，现在认为这个步骤很重要，代码是次要的，决策和为什么这样搞才是关键。

一句话概括吧，AssetBundle实现了资源与服务分离，方便做热更新。

一、创建AssetBundle

两步：1.设置AssetBundleName；2.调用BuildPipeline.BuildAssetBundles。详细过程如下：

设置AssetBundleName有两种方式，分为手动和代码

先讲手动，找到你需要被打包的文件，然后如下图

方式2，代码设置这个AssetBundleName，代码如下，创建bundle的代码也一起贴上了：

using UnityEngine;
using System.IO;
#if UNITY_EDITOR
using UnityEditor;
#endif

public class BuildBundleMenu : MonoBehaviour {

	public static string sourcePathPrefab = Application.dataPath + "/_Creepy_Cat/Realistic_Weather_Effects/_Prefabs/";
	public static string sourcePathMater = Application.dataPath + "/_Creepy_Cat/Realistic_Weather_Effects/_Materials/";

	#if UNITY_EDITOR
	[MenuItem( "Example/Build Asset Bundles" )]
	static void BuildABs( )
	{

		ClearAssetBundlesName ();  

		FindAllFile (sourcePathPrefab);
		FindAllFile (sourcePathMater); 

		// Put the bundles in a folder called "ABs" within the Assets folder.
		BuildPipeline.BuildAssetBundles( "Assets/ABs", BuildAssetBundleOptions.UncompressedAssetBundle, BuildTarget.StandaloneOSXIntel64);
	}

	/// <summary>
	/// 清除之前设置过的AssetBundleName，避免产生不必要的资源也打包
	/// 之前说过，只要设置了AssetBundleName的，都会进行打包，不论在什么目录下
	/// </summary>
	static void ClearAssetBundlesName()
	{
		int length = AssetDatabase.GetAllAssetBundleNames ().Length;
		Debug.Log (length);
		string[] oldAssetBundleNames = new string[length];
		for (int i = 0; i < length; i++)
		{
			oldAssetBundleNames[i] = AssetDatabase.GetAllAssetBundleNames()[i];
		}  

		for (int j = 0; j < oldAssetBundleNames.Length; j++)
		{
			AssetDatabase.RemoveAssetBundleName(oldAssetBundleNames[j],true);
		}
		length = AssetDatabase.GetAllAssetBundleNames ().Length;
		Debug.Log (length);
	}  

   	/// <summary>
   	/// 遍历文件夹里面的所有文件夹和文件
   	/// </summary>
   	/// <param name="source"></param>
	static void FindAllFile(string source)
	{
		DirectoryInfo folder = new DirectoryInfo (source);
		FileSystemInfo[] files = folder.GetFileSystemInfos ();
		int length = files.Length;
		for (int i = 0; i < length; i++) {
			if(files[i] is DirectoryInfo)
			{
				FindAllFile(files[i].FullName);
			}
			else
			{
				if(!files[i].Name.EndsWith(".meta"))
				{
					SetAssetName (files[i].FullName);
				}
			}
		}
	}  

	/// <summary>
	/// 为需要打包的文件设置assetName.
	/// </summary>
	/// <param name="source"></param>
	static void SetAssetName(string source)
	{
		string _assetPath = "Assets" + source.Substring (Application.dataPath.Length);
		//string _assetPath2 = source.Substring (Application.dataPath.Length + 1);
		//在代码中给资源设置AssetBundleName
		AssetImporter assetImporter = AssetImporter.GetAtPath (_assetPath);
		//string assetName = _assetPath2.Substring (_assetPath2.IndexOf("/") + 1);
		//assetName = assetName.Replace(Path.GetExtension(assetName),".unity3d");
		//assetImporter.assetBundleName = assetName;
		assetImporter.assetBundleName = "Weather.unity3d";
	}
	#endif
}

　　菜单栏会出现这个，点一下就可以了，bundle创建完成。注意打bundle前要现在Assets目录下新建一个ABs文件夹，打的bundle都在这个文件夹里面。

注：只要设置了AssetBundleName的，都会进行打包，不论在什么目录下。

二、bundle的加载

直接贴代码吧

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

public class LoadAssetbundle : MonoBehaviour {

	private string pathurl = "";
	// Use this for initialization
	void Start () {
		string pathPrefab = "file://" + Application.dataPath + "/ABs/weather.unity3d";

		StartCoroutine (LoadALLGameObject(pathPrefab));
	}

	//读取全部资源
	private IEnumerator LoadALLGameObject(string path)
	{  

		WWW bundle = new WWW(path);  

		yield return bundle;  

		//通过Prefab的名称把他们都读取出来
		Object  obj0 =  bundle.assetBundle.LoadAsset("CloudStorm_02_8x8-64.prefab");   

		//加载到游戏中
		yield return Instantiate(obj0);
		bundle.assetBundle.Unload(false);
	}
}