# AssetBundle 创建与加载

AssetBundle 只能用代码创建和加载
在创建前需要先为资源分配资源包，如图：

# AssetBundle 创建

区分平台（Windows、OSX、Linux 等）
区分创建方式（是否压缩、压缩方式等）
lua 文件无法被打包，本文使用的方法是：生成 .lua 文件对应的 .txt 文件，将 .txt 文件打包，然后删除生成的 .txt 文件

	using System.Collections.Generic;
	using System.IO;
	using System.Text;
	using UnityEditor;
	using UnityEngine;

	namespace Common
	{
	/// <summary>
	/// CreateAssetBundles
	/// </summary>
	public class CreateAssetBundles
	{
	/// <summary>
	/// BuildAllAssetBundles
	/// </summary>
	[MenuItem("Build/Build AssetBundles")]
	private static void BuildAllAssetBundles()
	{
	// 自定义路径
	//string assetBundleDirectory = EditorUtility.OpenFolderPanel ("选择导出路径", Application.dataPath, "");
	//if (string.IsNullOrEmpty(assetBundleDirectory))
	//{
	// return;
	//}

	string assetBundleDirectory = Application.streamingAssetsPath + "/AssetBundles";

	BuildAssetBundleOptions assetBundleOptions;
	BuildTarget targetPlatform;

	#if UNITY_STANDALONE_WIN //Windows 独立平台应用程序
	assetBundleOptions = BuildAssetBundleOptions.UncompressedAssetBundle;
	targetPlatform = BuildTarget.StandaloneWindows64;
	#elif UNITY_WSA //UWP
	assetBundleOptions = BuildAssetBundleOptions.UncompressedAssetBundle;
	targetPlatform = BuildTarget.WSAPlayer;
	#elif UNITY_STANDALONE_OSX //Mac OS X（包括 Universal、PPC 和 Intel 架构）
	assetBundleOptions = BuildAssetBundleOptions.UncompressedAssetBundle;
	targetPlatform = BuildTarget.StandaloneOSX;
	#elif UNITY_STANDALONE_LINUX //Linux
	assetBundleOptions = BuildAssetBundleOptions.UncompressedAssetBundle;
	targetPlatform = BuildTarget.StandaloneLinux;
	#elif UNITY_ANDROID
	assetBundleOptions = BuildAssetBundleOptions.ChunkBasedCompression;
	targetPlatform = BuildTarget.Android;
	#elif UNITY_IOS
	assetBundleOptions = BuildAssetBundleOptions.ChunkBasedCompression;
	targetPlatform = BuildTarget.iOS;
	#elif UNITY_WEBGL
	assetBundleOptions = BuildAssetBundleOptions.ChunkBasedCompression;
	targetPlatform = BuildTarget.WebGL;
	#endif

	if (!Directory.Exists(assetBundleDirectory))
	{
	Directory.CreateDirectory(assetBundleDirectory);
	}
	else
	{
	Directory.Delete(assetBundleDirectory, true);
	Directory.CreateDirectory(assetBundleDirectory);
	}

	string[] allTxtPaths = CopyLuaToTxt();

	GetFilesInfo();

	BuildPipeline.BuildAssetBundles(assetBundleDirectory, assetBundleOptions, targetPlatform);

	DeleteTxtFiles(allTxtPaths);

	AssetDatabase.Refresh();
	}

	/// <summary>
	/// 获取文件信息，用于调试
	/// </summary>
	private static void GetFilesInfo()
	{
	string[] bundleNames = AssetDatabase.GetAllAssetBundleNames();
	List<string> allAssetPaths = new List<string>();

	foreach (string bundleName in bundleNames)
	{
	string[] assetPaths = AssetDatabase.GetAssetPathsFromAssetBundle(bundleName);
	allAssetPaths.AddRange(assetPaths);
	}

	StringBuilder stringBuilder = new StringBuilder();
	stringBuilder.AppendLine("All AB paths:");

	foreach (string path in allAssetPaths)
	{
	stringBuilder.AppendLine(path);
	}

	Debug.Log(stringBuilder.ToString());
	}

	/// <summary>
	/// 将 .lua 文件转换为 .txt 文件
	/// </summary>
	/// <returns>.txt 文件路径 & lt;/returns>
	private static string[] CopyLuaToTxt()
	{
	string[] bundleNames = AssetDatabase.GetAllAssetBundleNames();
	List<string> allAssetPaths = new List<string>();
	List<string> allTxtPaths = new List<string>();

	foreach (string bundleName in bundleNames)
	{
	string[] assetPaths = AssetDatabase.GetAssetPathsFromAssetBundle(bundleName);
	allAssetPaths.AddRange(assetPaths);
	}

	foreach (string path in allAssetPaths)
	{
	if (path.EndsWith(".lua"))
	{
	// 读取.lua 文件内容
	var utf8 = new System.Text.UTF8Encoding(false);
	string content = File.ReadAllText(path, utf8);

	// 构造对应的.txt 文件路径
	string txtPath = Path.ChangeExtension(path, "txt");
	File.WriteAllText(txtPath, content, utf8);

	allTxtPaths.Add(txtPath);
	}
	}

	AssetDatabase.Refresh();

	return allTxtPaths.ToArray();
	}

	/// <summary>
	/// 删除 .txt 文件
	/// </summary>
	/// <param name="dir"></param>
	private static void DeleteTxtFiles(string[] allTxtPaths)
	{
	foreach (string path in allTxtPaths)
	{
	AssetDatabase.DeleteAsset(path);
	}
	}
	}
	}

# AssetBundle 加载

两种加载方式：通过网络请求加载（UnityWebRequest）、通过本地存储加载（AssetBundle.LoadFromFile ()）
- 本工具类中使用网络请求加载方式，目的是为了适配更多的设备
同一个 ab 包中如果有多个同名文件，则只会加载第一个匹配的文件
加载目标 ab 包前，需要先加载它的依赖 ab 包（如果存在）
加载目标 ab 包后，调用委托处理其他逻辑
加载的 ab 包在使用完后需要卸载，防止占用内存

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

	namespace Common
	{
	/// <summary>
	/// AB 包管理器
	/// </summary>
	public static class AssetBundleManager
	{
	/// <summary>
	/// 加载资源包
	/// </summary>
	/// <param name="body"> 执行对象 & lt;/param>
	/// <param name="path"> 路径 & lt;/param>
	/// <param name="action"> 委托 & lt;/param>
	public static void LoadAssetBundle(this MonoBehaviour body, string path, Action<AssetBundle> action)
	{
	body.StartCoroutine(LoadAssetBundle_(path, action));
	}

	/// <summary>
	/// 加载资源包
	/// </summary>
	/// <param name="path"> 路径 & lt;/param>
	/// <param name="action"> 委托 & lt;/param>
	/// <returns></returns>
	private static IEnumerator LoadAssetBundle_(string path, Action<AssetBundle> action)
	{
	string assetBundleName = path.Split('/')[^1];
	string startPath = path.Substring(0, path.LastIndexOf('/'));

	// 获取 AssetBundles 文件
	UnityWebRequest request_0 = UnityWebRequestAssetBundle.GetAssetBundle(startPath + "/AssetBundles", 0);
	yield return request_0.SendWebRequest();

	if (request_0.result != UnityWebRequest.Result.Success)
	{
	Debug.LogError("Failed to load AssetBundle：" + request_0.error);
	}
	else
	{
	AssetBundle bundle_0 = DownloadHandlerAssetBundle.GetContent(request_0);

	// 获取 manifest 文件
	AssetBundleManifest manifest_0 = bundle_0.LoadAsset("AssetBundleManifest") as AssetBundleManifest;
	bundle_0.Unload(false);

	// 查找并加载依赖文件
	string[] dependencies = manifest_0.GetAllDependencies(assetBundleName);
	AssetBundle[] bundles = new AssetBundle[dependencies.Length];

	for (int i = 0; i < dependencies.Length; i++)
	{
	string dependenciesPath = startPath + '/' + dependencies[i];
	UnityWebRequest requests = UnityWebRequestAssetBundle.GetAssetBundle(dependenciesPath, 0);
	yield return requests.SendWebRequest();

	if (requests.result != UnityWebRequest.Result.Success)
	{
	Debug.LogError("Failed to load AssetBundle：" + requests.error);
	}
	else
	{
	bundles[i] = DownloadHandlerAssetBundle.GetContent(requests);
	}
	}

	// 取出资源
	UnityWebRequest request = UnityWebRequestAssetBundle.GetAssetBundle(path, 0);
	yield return request.SendWebRequest();

	if (request.result != UnityWebRequest.Result.Success)
	{
	Debug.LogError("Failed to load AssetBundle：" + request.error);
	}
	else
	{
	AssetBundle bundle = DownloadHandlerAssetBundle.GetContent(request);
	action(bundle);
	bundle.Unload(false);
	}

	foreach (AssetBundle item in bundles)
	{
	item.Unload(false);
	}
	}
	}
	}
	}

# 使用方法

创建
点击按钮创建 ab 包，如图：

加载

	using Common;
	using UnityEngine;

	namespace Default
	{
	/// <summary>
	/// AB 包测试
	/// </summary>
	public class ABTest : MonoBehaviour
	{
	private void Start()
	{
	this.LoadAssetBundle(Application.streamingAssetsPath + "/AssetBundles/lua_bundles", TestAction);
	}

	private void TestAction(AssetBundle bundle)
	{
	TextAsset receive = bundle.LoadAsset<TextAsset>("main");
	Debug.Log(receive.text);
	}
	}
	}