AssetBundle資源打包與加載

AssetBundle資源打包

 1.AssetLabels資源標籤

　　文件名:資源打包成AssetBundle後的文件名,相似於壓縮包的名字
　　後綴:自定義
　　文件名和後綴名都是小寫格式(大寫會自動轉爲小寫)
2. BuildPipeline.BuildAssetBundles(string outputPath, BuildAssetBundleOptions assetBundleOptions, BuildTarget targetPlatform) 打包全部設置了AssetLabel的資源
　　outputPath:路徑,打包出來的AssetBunlde文件存放的位置
　　BuildAssetBundleOptions:選項,設置AssetBundle打包過程當中壓縮方式

　　　　BuildAssetBundleOptions枚舉選項:

　　　　　　None使用LZMA壓縮算法進行壓縮,打包後資源體積最小
　　　　　　UncompressedAssetBundle不壓縮,打包後的AssetBundle體積最大,可是加載速度最快
　　　　　　ChunkBasedCompression使用LZ4壓縮算法進行壓縮,打包後的AssetBundle體積和加載速度介於上面兩者之間
　　BuildTarget:平臺,AssetBundle是平臺之間不兼容的,IOS,Android是兩套資源

　　
在AssetLabels區域填寫AssetBundle名稱的時候,名稱是能夠分目錄嵌套的:文件夾名/文件名

 

AssetBundle打包後的資源包,分兩部分組成:

　　1.資源打包出來的AssetBundle文件
　　2.AssetBundle文件配套的manifest文本文件

manifest文件

manifest文件用於專門存儲打包後的AssetBundle文件的基本信息,主要包含:
　　CRC校驗碼:相似於MD5,用於計算出該資源的一個特殊信息標示
　　ClassTypes列表:當前資源關聯使用到了Unity中的哪些類,這些類是以編號索引的形式存在的,每一個編號都對應一個類文件
　　Assets:AssetsBundle裏包含了哪些資源文件
　　Dependencies:依賴

 在打包出來的AssetBundle文件中,有一個特殊的manifest文件,和AssetBundle存放的文件夾同名,且只在根文件夾下有惟一的一個

這個manifest文件能夠稱做"AssetBundle目錄文件",它存儲了打包出來的全部AssetBundle的文件的索引信息
經過這個目錄文件,能夠找到全部的AssetBundle文件

 

AssetBundle資源加載

將項目資源打包成AssetBundle後,通常有兩種操做

一.將這些AssetBundle留着項目工程中,當成普通資源使用

　　1.加載AssetBundle資源到內存

　　　　AssetBundle ab =  AssetBundle.LoadFromFile("路徑");加載AssetBundle資源到內存,返回一個AssetBundle對象

        2.從AssetBundle中獲取資源

　　　　T res = ab.LoadAsset<T>("資源名");

　　 3.實例化

打包

[MenuItem("xx/xxx")] 
public static void Build_WINDOWS64()
{
　　string outputPath = Path.Combine(Application.streamingAssetsPath, "Data");
　　if (!Directory.Exists(outputPath))
　　　　Directory.CreateDirectory(outputPath);

　　BuildPipeline.BuildAssetBundles(outputPath, BuildAssetBundleOptions.None, BuildTarget.StandaloneWindows64);//本身選擇平臺
　　AssetDatabase.Refresh();
}

加載

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

public class AssetBundleManager
{
    private readonly string _path = UnityEngine.Application.streamingAssetsPath + "/Data/";
    private static AssetBundleManager _instance;
    private bool mIsLoadingEnd = false;
    public bool IsLoadingEnd { get { return mIsLoadingEnd; } }
    private List<string> mLoadingNames;
    private Dictionary<string, UnityEngine.Object> mAssets;
    private Dictionary<string, UnityEngine.Texture2D> mTexture2Ds;

    public static AssetBundleManager GetInstance()
    {
        if (_instance == null)
        {
            _instance = new AssetBundleManager();
        }
        return _instance;
    }
    
    private AssetBundleManager()
    {
        mLoadingNames = new List<string>(){
            //todo:要加載的資源名
        };

        mAssets = new Dictionary<string, UnityEngine.Object>();
        mTexture2Ds = new Dictionary<string, UnityEngine.Texture2D>();
    }
    
    /// <summary>
    /// 加載assetsbundle
　　 /// 記得先加載到內存StartCoroutine(AssetBundleManager.GetInstance().Loading());
    /// </summary>
    public IEnumerator Loading()
    {
        foreach (var nameAndType in mLoadingNames)
        {
            string filename = _path + nameAndType.ToLower();
            UnityEngine.AssetBundleCreateRequest request = UnityEngine.AssetBundle.LoadFromFileAsync(filename);
            yield return request;
            LoadAsset(request.assetBundle);
        }
        mIsLoadingEnd = true;
    }

    private UnityEngine.AssetBundle LoadAssetBundle(string fileName)
    {
        UnityEngine.AssetBundle AB = UnityEngine.AssetBundle.LoadFromFile(_path + fileName);
        return AB;
    }

    private void LoadAsset(UnityEngine.AssetBundle ab)
    {
        UnityEngine.Object[] assets = ab.LoadAllAssets();
        for (int i = 0; i < assets.Length; i++)
        {
            //一張圖片的AssetsBundle包含自身Texture2D和它裏面所有Sprite,有可能重名
            if (!typeof(UnityEngine.Texture2D).Equals(assets[i].GetType()))
                mAssets.Add(assets[i].name, assets[i]);
            else
                mTexture2Ds.Add(assets[i].name, assets[i] as UnityEngine.Texture2D);
        }
    }

    /// <summary>
    /// 從assetbundle獲取texture2d
    /// </summary>
    public UnityEngine.Texture2D GetTexture2D(string name)
    {
        UnityEngine.Texture2D obj;
        mTexture2Ds.TryGetValue(name, out obj);
        return obj;
    }

    /// <summary>
    /// 從assetbundle獲取Object
    /// </summary>
    public UnityEngine.Object GetAsset(string name)
    {
        UnityEngine.Object obj;
        mAssets.TryGetValue(name, out obj);
        return obj;
    }
}

二.將這些AssetBundle上傳服務器,客戶端第一次運行時從服務器下載AssetBundle緩存到本地再使用(實現客戶端的安裝包與資源分離,下降客戶端安裝包的體積)

 1.服務器端下載主文件

    從服務器端下載AssetBundle須要web路徑地址,每個地址對應一個AssetBundle文件.咱們不可能在代碼中寫幾十上百個文件的web地址,因此咱們須要先下載"目錄AssetBundle文件",而後經過它來間接獲取其餘AssetBundle文件的下載路徑地址.

須要引入命名空間using UnityEngine.Networking;

using System.Collections;
using System.IO;
using UnityEngine;
using UnityEngine.Networking;

public class TestAssetBundle : MonoBehaviour
{
    private string mainAssetBundleURL = @"http://www.xxx.com.xxx/AssetBundleFile";
    private string allAssetBundleURL =  @"http://www.xxx.com.xxx/";

    void Start()
    {
        StartCoroutine(DownloadMainAssetBundle());
    }

    /// <summary>
    /// 下載目錄AssetBundle文件
    /// </summary>
    IEnumerator DownloadMainAssetBundle()
    {
        //建立一個獲取AssetBundle文件的web請求
        UnityWebRequest request = UnityWebRequestAssetBundle.GetAssetBundle(mainAssetBundleURL);

        //發送web請求
        yield return request.SendWebRequest();

        //從請求中獲取內容,返回AssetBundle類型的數據
        AssetBundle ab = DownloadHandlerAssetBundle.GetContent(request);

        //從"目錄AssetBundle"中獲取manifest數據
        AssetBundleManifest manifest = ab.LoadAsset<AssetBundleManifest>("AssetBundleManifest");

        //獲取manifest文件中全部的AssetBundle的名稱信息
        string[] names = manifest.GetAllAssetBundles();

        foreach (var name in names)
        {
            StartCoroutine(DownloadAssetBundleAndSave(allAssetBundleURL + name));
        }
    }
    
    /// <summary>
    /// 下載AssetBundle並保存到本地
    /// </summary>
    IEnumerator DownloadAssetBundleAndSave(string url)
    {
        UnityWebRequest request = UnityWebRequest.Get(url);
        yield return request.SendWebRequest();
        // 截取路徑地址中的文件名(須要引入System.IO)
        string fileName = Path.GetFileName(url);
        SaveAssetBundle(fileName, request.downloadHandler.data);
    }

    /// <summary>
    /// 存儲AssetBundle爲本地文件
    /// </summary>
    private void SaveAssetBundle(string fileName, byte[] bytes)
    {
        //建立一個文件信息對象(System.IO)
        FileInfo fileInfo = new FileInfo(Application.streamingAssetsPath + "//" + fileName);

        //建立一個文件流對象
        FileStream fs = fileInfo.Create();

        //經過文件流對象,往文件內寫入信息
        fs.Write(bytes, 0, bytes.Length);

        //文件寫入存儲到硬盤
        fs.Flush();

        //關閉文件流對象
        fs.Close();

        //銷燬文件對象
        fs.Dispose();
    }
}