AssetBundle入门笔记02

AB包加载的四种方式

1.AssetBundle.LoadFromMemoryAsync(从内存中加载)
异步：

   IEnumerator LoadFromMemoryAsync(string path)
    {        
        AssetBundleCreateRequest createRequest = AssetBundle.LoadFromMemoryAsync(File.ReadAllBytes(path));
        yield return createRequest; //等待加载完成
        AssetBundle bundle = createRequest.assetBundle;
        GameObject greenCube = bundle.LoadAsset("greenCube");
        Instantiate(greenCube);
    }

同步：

    void LoadFromMemory(string path)
    {
        AssetBundle bundle = AssetBundle.LoadFromMemory(File.ReadAllBytes(path));
        GameObject greenCube = bundle.LoadAsset("greenCube");
        Instantiate(greenCube);
    }

File.ReadAllBytes(path)可以用任何的字节数组来取代。

2.AssetBundle.LoadFromFile(从文件中加载)
如果包是未压缩的或者块（LZ4）压缩的，LoadFromFile将直接从磁盘加载；如果是完全压缩（LZMA）包将先解压缩包再加载

  void LoadFromFile(string path)
    {
        AssetBundle bundle = AssetBundle.LoadFromFile(path);
        if (bundle == null)
        {
            Debug.Log("Failed to load AssetBundle!");
            return;
        }
        GameObject greenCube = bundle.LoadAsset("greenCube");
        Instantiate(greenCube);
    }

3.WWW.LoadFromCacheOrDownload（已被4取代）
可以从远程服务器下载AssetBundles或加载本地AssetBundles

  IEnumerator Start()
    {
        while (!Caching.ready)
            yield return null;//返回null挂起一帧
        //输入地址+版本号，地址需要绝对路径
        WWW www = WWW.LoadFromCacheOrDownload(@"file://F:\Unity3D Little Games\AssetBundle_Learning\MY_AssetBundles\cube.ab", 1);
        // WWW www = WWW.LoadFromCacheOrDownload(@"http://localhost/MY_AssetBundles/cube.ab", 1);//服务器路径
        yield return www;
        if (!string.IsNullOrEmpty(www.error))
        {
            Debug.Log(www.error);
            yield break;
        }
        AssetBundle bundle = www.assetBundle;
        GameObject greenCube = bundle.LoadAsset("greenCube");
        Instantiate(greenCube);
    }

crc参数是manifest文件里面的一串校验码，主要用来检测或校验数据传输或者保存后可能出现的错误

4.UnityWebRequest

  IEnumerator WebRequest()
    {
        //string uri = @"file://F:\Unity3D Little Games\AssetBundle_Learning\MY_AssetBundles\cube.ab";//本地地址
        string uri = @"http://localhost/MY_AssetBundles\cube.ab";//服务器地址
        UnityWebRequest request = UnityWebRequest.GetAssetBundle(uri);
        yield return request.Send();//等待下载完成
        AssetBundle bundle = DownloadHandlerAssetBundle.GetContent(request);
        //另一种方法
        //AssetBundle bundle = (request.downloadHandler as DownloadHandlerAssetBundle).assetBundle;

        GameObject greenCube = bundle.LoadAsset("greenCube");
        Instantiate(greenCube);
    }

---

使用AB包

• 加载单个Gameobject：

GameObject gameObject = loadedAssetBundle.LoadAsset(assetName);

• 加载所有：

Unity.Object[] objectArray = loadedAssetBundle.LoadAllAssets();

• 异步加载：

AssetBundleRequest request = loadedAssetBundleObject.LoadAssetAsync(Name);
yield return request;
var loadedAsset = request.asset;

AssetBundleRequest request = loadedAssetBundle.LoadAllAssetsAsync();
yield return request;
var loadedAssets = request.allAssets;

---

加载AB包清单（manifest）

 void LoadManifest()
    {
        AssetBundle manifestAB = AssetBundle.LoadFromFile("MY_AssetBundles/MY_AssetBundles");//加载总包
        AssetBundleManifest manifest = manifestAB.LoadAsset("AssetBundleManifest");//加载总包的manifest
        string[] asset_names = manifest.GetAllAssetBundles();//获取每个包的名字       
        string[] strs = manifest.GetDirectDependencies("Cube.ab");//获取某个包所依赖的所有包的名字
        foreach (string item in strs)
        {
            AssetBundle.LoadFromFile("MY_AssetBundles/" + item);//加载每个依赖包
        }

        AssetBundle cubes = AssetBundle.LoadFromFile("MY_AssetBundles/" + asset_names[0]);//获得第一个包
        GameObject cube = cubes.LoadAsset("Cube");
        Instantiate(cube);
    }

---

AB包的卸载

• 卸载的好坏
  1.减少内存使用
  2.有可能导致丢失

• 什么时候去卸载资源
  AssetBundle.Unload(true) : 卸载所有资源，即使有资源被使用着
  （1.在关卡切换、场景切换 2.资源没被用的时候调用）
  AssetBundle.Unload(false) : 卸载所有没用被使用的资源
  个别资源卸载问题：
  1.通过 Resources.UnloadUnusedAssets.
  2.场景切换的时候

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AB包浏览工具

下载地址