WWW.LoadFromCacheOrDownload 加载自缓存或下载

WWW.LoadFromCacheOrDownload 加载自缓存或下载

static function LoadFromCacheOrDownload (url : String, version : int) : WWW

Parameters参数

• string
  url The URL to download the data from (if it is not cached). @paramint   version Version of the data. The file will only be loaded from the disk   cache if it has previously been downloaded with the same version parameter. This lets you force clients to re-download updated data from the network.
     url是从该URL下载数据（如果没有被缓存）。version是@paramint数据的版本。如果文件带有相同版本参数之前已经被下载，该文件只能从磁盘高速缓存中加载。这使您可以从网络强制客户端重新下载更新的数据。
• integer
  Version of the AssetBundle. The file will only be loaded from the disk cache if it has previously been downloaded with the same version parameter. By incrementing the version number requested by your application, you can force Caching to download a new copy of the AssetBunlde from url.
     AssetBundle的版本。 如果以前曾用同一版本的参数下载，该文件将只从磁盘高速缓存加载。通过增加应用程序的版本号，你可以强制缓存从URL下载一个新AssetBunlde的副本。

Returns

WWW - a WWW instance, which can be used to access the data once the load/download operation is completed.

返回一个WWW实例，一旦加载或下载操作完成，可用于访问数据。

Description描述

Loads an AssetBundle with the specified version number from the cache. If the AssetBundle is not currently cached, it will automatically be downloaded and stored in the cache for future retrieval from local storage.

从缓存加载一个带有特定版本号的资源包，如果资源包目前没有被缓存，或从下载加载。它将自动下载并储存在高速缓存区以便将来从本地储存中读取。

LoadFromCacheOrDownload() must be used in place of "new WWW (url)" in order to utilize caching functionality.  Cached AssetBundles are uniquely identified solely by the filename and version number; all domain and path information in url   is ignored by Caching. Since cached AssetBundles are identified by   filename instead of the full URL, you can change the directory from   where the asset bundle is downloaded at any time. This is useful for   pushing out new versions of the game and ensuring that files are not   cached incorrectly by the browser or by a CDN. For WebPlayer   applications that use the shared cache, Caching adds unique identifying   information to identically-named AssetBundles in order to prevent name   collisions between applications.  If the cache folder does not have any space for caching additional   files, LoadFromCacheOrDownload will iteratively delete the   least-recently-used AssetBundles from the Cache until sufficient space   is available to store the new AssetBundle. If making space is not   possible (because the hard disk is full, or all files in the cache are   currently in use), LoadFromCacheOrDownload() will bypass Caching and   stream the file into memory like a normal "new WWW()" call.  This function can only be used to access AssetBundles. No other types or   content are cacheable.

LoadFromCacheOrDownload()取代"new WWW (url)"为了充分利用缓存功能。缓存的资源包完全由文件名和版本号唯一标识；URL所有域名和路径信息在缓存被忽略。由于缓存的资源包通过文件名而不是完整的URL来识别，在任何时候资源包被下载，你可以更改目录。对于推出了游戏的新版本确保文件通过浏览器或CDN不是错误的缓存，这是很有用的。对于网络播放器应用程序使用共享缓存，缓存增加了唯一标识信息为了防止应用程序间同名的资源包名称冲突。如果缓存文件夹中没有任何空间来缓存额外的文件，LoadFromCacheOrDownload会反复从缓存中删除最近最少使用资源包，直到有足够的空间可用来存储新的资源包。如果利用空间是不可能的（因为硬盘已满，或所有缓存文件在使用），LoadFromCacheOrDownload()将绕过缓存并流传输文件到内存，就像一个普通的"new WWW()"调用。这个函数只能访问资源包。无其他类型或内容可缓存。

参见： BuildPipeline.BuildAssetBundle, BuildPipeline.BuildStreamedSceneAssetBundle.

function Start (){    var www = WWW.LoadFromCacheOrDownload ("http://myserver.com/myassetBundle.unity3d", 5);    yield www;    if (www.error != null)    {        Debug.Log (www.error);        return;    }    var myLoadedAssetBundle = www.assetBundle;    var asset = myLoadedAssetBundle.mainAsset;}