AssetBundle资源打包与加载

AssetBundle资源打包

1.AssetLabels资源标签

　　文件名:资源打包成AssetBundle后的文件名,类似于压缩包的名字
　　后缀:自定义
　　文件名和后缀名都是小写格式(大写会自动转为小写)
2. BuildPipeline.BuildAssetBundles(string outputPath, BuildAssetBundleOptions assetBundleOptions, BuildTarget targetPlatform) 打包所有设置了AssetLabel的资源
　　outputPath:路径,打包出来的AssetBunlde文件存放的位置
　　BuildAssetBundleOptions:选项,设置AssetBundle打包过程中压缩方式

　　　　BuildAssetBundleOptions枚举选项:

None使用LZMA压缩算法进行压缩,打包后资源体积最小
　　　　　　UncompressedAssetBundle不压缩,打包后的AssetBundle体积最大,但是加载速度最快
　　　　　　ChunkBasedCompression使用LZ4压缩算法进行压缩,打包后的AssetBundle体积和加载速度介于上面二者之间
　　BuildTarget:平台,AssetBundle是平台之间不兼容的,IOS,Android是两套资源

在AssetLabels区域填写AssetBundle名称的时候,名称是可以分目录嵌套的:文件夹名/文件名

AssetBundle打包后的资源包,分两部分组成:

　　1.资源打包出来的AssetBundle文件
　　2.AssetBundle文件配套的manifest文本文件

manifest文件

manifest文件用于专门存储打包后的AssetBundle文件的基本信息,主要包含:
　　**CRC校验码:**类似于MD5,用于计算出该资源的一个特殊信息标示
**ClassTypes列表:**当前资源关联使用到了Unity中的哪些类,这些类是以编号索引的形式存在的,每个编号都对应一个类文件
**Assets:**AssetsBundle里包含了哪些资源文件
**Dependencies:**依赖

 在打包出来的AssetBundle文件中,有一个特殊的manifest文件,和AssetBundle存放的文件夹同名,且只在根文件夹下有唯一的一个

这个manifest文件可以称作"AssetBundle目录文件",它存储了打包出来的所有AssetBundle的文件的索引信息
通过这个目录文件,可以找到所有的AssetBundle文件

AssetBundle资源加载

将项目资源打包成AssetBundle后,一般有两种操作

一.将这些AssetBundle留着项目工程中,当成普通资源使用

1.加载AssetBundle资源到内存****

****AssetBundle ab =  AssetBundle.LoadFromFile("路径");加载AssetBundle资源到内存,返回一个AssetBundle对象

2.从AssetBundle中获取资源****

T res = ab.LoadAsset<T>("资源名");

3.实例化

打包

1[MenuItem("xx/xxx")] 
2public static void Build_WINDOWS64()
3{
4　　string outputPath = Path.Combine(Application.streamingAssetsPath, "Data");
5　　if (!Directory.Exists(outputPath))
6　　　　Directory.CreateDirectory(outputPath);
7
8　　BuildPipeline.BuildAssetBundles(outputPath, BuildAssetBundleOptions.None, BuildTarget.StandaloneWindows64);//自己选择平台
9　　AssetDatabase.Refresh();
10}

加载

1using System.Collections;
2using System.Collections.Generic;
3
4public class AssetBundleManager
5{
6    private readonly string _path = UnityEngine.Application.streamingAssetsPath + "/Data/";
7    private static AssetBundleManager _instance;
8    private bool mIsLoadingEnd = false;
9    public bool IsLoadingEnd { get { return mIsLoadingEnd; } }
10    private List<string> mLoadingNames;
11    private Dictionary<string, UnityEngine.Object> mAssets;
12    private Dictionary<string, UnityEngine.Texture2D> mTexture2Ds;
13
14    public static AssetBundleManager GetInstance()
15    {
16        if (_instance == null)
17        {
18            _instance = new AssetBundleManager();
19        }
20        return _instance;
21    }
22    
23    private AssetBundleManager()
24    {
25        mLoadingNames = new List<string>(){
26            //todo:要加载的资源名
27        };
28
29        mAssets = new Dictionary<string, UnityEngine.Object>();
30        mTexture2Ds = new Dictionary<string, UnityEngine.Texture2D>();
31    }
32    
33    /// <summary>
34    /// 加载assetsbundle　　 /// 记得先加载到内存StartCoroutine(AssetBundleManager.GetInstance().Loading());
35    /// </summary>
36    public IEnumerator Loading()
37    {
38        foreach (var nameAndType in mLoadingNames)
39        {
40            string filename = _path + nameAndType.ToLower();
41            UnityEngine.AssetBundleCreateRequest request = UnityEngine.AssetBundle.LoadFromFileAsync(filename);
42            yield return request;
43            LoadAsset(request.assetBundle);
44        }
45        mIsLoadingEnd = true;
46    }
47
48    private UnityEngine.AssetBundle LoadAssetBundle(string fileName)
49    {
50        UnityEngine.AssetBundle AB = UnityEngine.AssetBundle.LoadFromFile(_path + fileName);
51        return AB;
52    }
53
54    private void LoadAsset(UnityEngine.AssetBundle ab)
55    {
56        UnityEngine.Object[] assets = ab.LoadAllAssets();
57        for (int i = 0; i < assets.Length; i++)
58        {
59            //一张图片的AssetsBundle包含自身Texture2D和它里面全部Sprite,有可能重名
60            if (!typeof(UnityEngine.Texture2D).Equals(assets[i].GetType()))
61                mAssets.Add(assets[i].name, assets[i]);
62            else
63                mTexture2Ds.Add(assets[i].name, assets[i] as UnityEngine.Texture2D);
64        }
65    }
66
67    /// <summary>
68    /// 从assetbundle获取texture2d
69    /// </summary>
70    public UnityEngine.Texture2D GetTexture2D(string name)
71    {
72        UnityEngine.Texture2D obj;
73        mTexture2Ds.TryGetValue(name, out obj);
74        return obj;
75    }
76
77    /// <summary>
78    /// 从assetbundle获取Object
79    /// </summary>
80    public UnityEngine.Object GetAsset(string name)
81    {
82        UnityEngine.Object obj;
83        mAssets.TryGetValue(name, out obj);
84        return obj;
85    }
86}

二.将这些AssetBundle上传服务器,客户端第一次运行时从服务器下载AssetBundle缓存到本地再使用(实现客户端的安装包与资源分离,降低客户端安装包的体积)****

1.服务器端下载主文件

从服务器端下载AssetBundle需要web路径地址,每一个地址对应一个AssetBundle文件.我们不可能在代码中写几十上百个文件的web地址,所以我们需要先下载"目录AssetBundle文件",然后通过它来间接获取其他AssetBundle文件的下载路径地址.

需要引入命名空间using UnityEngine.Networking;

1using System.Collections;
2using System.IO;
3using UnityEngine;
4using UnityEngine.Networking;
5
6public class TestAssetBundle : MonoBehaviour
7{
8    private string mainAssetBundleURL = @"http://www.xxx.com.xxx/AssetBundleFile";
9    private string allAssetBundleURL =  @"http://www.xxx.com.xxx/";
10
11    void Start()
12    {
13        StartCoroutine(DownloadMainAssetBundle());
14    }
15
16    /// <summary>
17    /// 下载目录AssetBundle文件
18    /// </summary>
19    IEnumerator DownloadMainAssetBundle()
20    {
21        //创建一个获取AssetBundle文件的web请求
22        UnityWebRequest request = UnityWebRequestAssetBundle.GetAssetBundle(mainAssetBundleURL);
23
24        //发送web请求
25        yield return request.SendWebRequest();
26
27        //从请求中获取内容,返回AssetBundle类型的数据
28        AssetBundle ab = DownloadHandlerAssetBundle.GetContent(request);
29
30        //从"目录AssetBundle"中获取manifest数据
31        AssetBundleManifest manifest = ab.LoadAsset<AssetBundleManifest>("AssetBundleManifest");
32
33        //获取manifest文件中所有的AssetBundle的名称信息
34        string[] names = manifest.GetAllAssetBundles();
35
36        foreach (var name in names)
37        {
38            StartCoroutine(DownloadAssetBundleAndSave(allAssetBundleURL + name));
39        }
40    }
41    
42    /// <summary>
43    /// 下载AssetBundle并保存到本地
44    /// </summary>
45    IEnumerator DownloadAssetBundleAndSave(string url)
46    {
47        UnityWebRequest request = UnityWebRequest.Get(url);
48        yield return request.SendWebRequest();
49        // 截取路径地址中的文件名(需要引入System.IO)
50        string fileName = Path.GetFileName(url);
51        SaveAssetBundle(fileName, request.downloadHandler.data);
52    }
53
54    /// <summary>
55    /// 存储AssetBundle为本地文件
56    /// </summary>
57    private void SaveAssetBundle(string fileName, byte[] bytes)
58    {
59        //创建一个文件信息对象(System.IO)
60        FileInfo fileInfo = new FileInfo(Application.streamingAssetsPath + "//" + fileName);
61
62        //创建一个文件流对象
63        FileStream fs = fileInfo.Create();
64
65        //通过文件流对象,往文件内写入信息
66        fs.Write(bytes, 0, bytes.Length);
67
68        //文件写入存储到硬盘
69        fs.Flush();
70
71        //关闭文件流对象
72        fs.Close();
73
74        //销毁文件对象
75        fs.Dispose();
76    }
77}