Unity3D游戏开发之跟踪已下载资源包浅析.docx

Unity3D游戏开发之跟踪已下载资源包浅析Keeping track of loaded AssetBundles跟踪已下载资源包      Unity 一次只允许加载一个特定资源包 (AssetBundle) 实例到应用程序中。这意味着您无法检索 WWW 对象中之前已加载的相同资源包 (AssetBundle) 或尚未加载的资源包。实际上，这意味着您尝试访问之前已下载的如下资源包 (AssetBundle) 时：AssetBundle bundle = www.assetBundle;    程序将引出以下错误Cannot load cached AssetBundle.A file of the same name is already loaded from another AssetBundle    且资源包属性将返回 null。如果第一次下载时下载了该资源包 (AssetBundle)，则第二次下载时无法检索到该资源包，因此，无需再使用该资源包时，可以将其卸载 或获取其引用，并在它存在于内存中时避免将其下载。可根据需求决定需要采取的相应措施，但我们建议在加载完对象后立即卸载该资源包 (AssetBundle)。这可释放内存空间，并且不会再收到有关加载已缓存资源包 (AssetBundles) 的错误。文章出处【狗刨学习网】如需跟踪已下载资源包 (AssetBundles)，可使用包装类协助管理下载，如下：1. using UnityEngine;2. using System;3. using System.Collections;4. using System.Collections.Generic;5.  6. static public class AssetBundleManager 7. / A dictionary to hold the AssetBundle references8. static private Dictionary<string, AssetBundleRef> dictAssetBundleRefs;9. static AssetBundleManager ()10. dictAssetBundleRefs = new Dictionary<string, AssetBundleRef>();11.    12. / Class with the AssetBundle reference, url and version13. private class AssetBundleRef 14. public AssetBundle assetBundle = null;15. public int version;16. public string url;17. public AssetBundleRef(string strUrlIn, int intVersionIn) 18. url = strUrlIn;19. version = intVersionIn;20.        21.    22. / Get an AssetBundle23. public static AssetBundle getAssetBundle (string url, int version)24. string keyName = url + version.ToString();25. AssetBundleRef abRef;26. if (dictAssetBundleRefs.TryGetValue(keyName, out abRef)27. return abRef.assetBundle;28. else29. return null;30.    31. / Download an AssetBundle32. public static IEnumerator downloadAssetBundle (string url, int version)33. string keyName = url + version.ToString();34. if (dictAssetBundleRefs.ContainsKey(keyName)35. yield return null;36. else 37. using(WWW www = WWW.LoadFromCacheOrDownload (url, version)38. yield return www;39. if (www.error != null)40. throw new Exception("WWW download:"+ www.error);41. AssetBundleRef abRef = new AssetBundleRef (url, version);42. abRef.assetBundle = www.assetBundle;43. dictAssetBundleRefs.Add (keyName, abRef);44.            45.        46.    47. / Unload an AssetBundle48. public static void Unload (string url, int version, bool allObjects)49. string keyName = url + version.ToString();50. AssetBundleRef abRef;51. if (dictAssetBundleRefs.TryGetValue(keyName, out abRef)52. abRef.assetBundle.Unload (allObjects);53. abRef.assetBundle = null;54. dictAssetBundleRefs.Remove(keyName);55.        56.    57. 请记住，本示例中的 AssetBundleManager 类是静态的，正在引用的任何资源包 (AssetBundles) 不会在加载新场景时销毁。请将此类当做指南例程，但正如最初建议的那样，最好在使用后立即卸载资源包 (AssetBundles)。您始终可以克隆之前实例化的对象，无需再下载该资源包 (AssetBundles)。文章出处【狗刨学习网】