保留.lua后缀名，将lua文件打包成assetbundle

开发ulua的同志们一定遇见过一个很大的坑，就是将lua文件打包成assetbundle的时候，unity引擎不识别lua文件，最后只好绕弯路把lua文件改成txt文件，然后才能打包。最后开发的时候，直接就用txt进行开发。这样子网上那么多lua的编辑器基本上都用不了，代码提示，跟代码查错都将给一些人很大的困扰，对于刚刚学习lua的人来说简直就是一种非常大的打击，从而使开发的门槛变高，对于整个项目来说是不利的。

对此我选择了一种曲线救国的方式，思想是打包assetbundle的时候，将.lua文件拷贝一份，在同一路径下存成.txt文件。然后调用打包assetbundle的指令，进行打包，打包完成后删除txt文件，从而让使用者只管在.lua文件里面开发就行。

直接上UnityEditor的代码。（不是很优雅，但是估计也勉强看得懂）

using UnityEngine;
using UnityEditor;
using System.IO;

public class ExportAssetBundles {

    //在Unity编辑器中添加菜单  
    [MenuItem("Assets/Build AssetBundle From Selection")]
    static void ExportResourceRGB2() {

        // 打开保存面板，获得用户选择的路径  
        string path = EditorUtility.SaveFolderPanel("Select Lua Script Folder", "", "");
        DirectoryInfo TheFolder = new DirectoryInfo(path);
        string bundlePath = path + "/" + TheFolder.Name + ".assetbundle";
        ChangeLua2Txt(TheFolder, path);

        bundlePath = EditorUtility.SaveFilePanel("Save Resource", "", TheFolder.Name, "assetbundle");
        AssetDatabase.Refresh();
        if (path.Length != 0) {
            // 选择的要保存的对象
            Object[] selection = Selection.GetFiltered(typeof(Object), SelectionMode.DeepAssets);
            //打包
            BuildPipeline.BuildAssetBundle(Selection.activeObject, selection, bundlePath, BuildAssetBundleOptions.CollectDependencies | BuildAssetBundleOptions.CompleteAssets, BuildTarget.StandaloneWindows);
            DeleteTxt(TheFolder);
            AssetDatabase.Refresh();
        }
    }
    static private void ChangeLua2Txt(DirectoryInfo TheFolder, string path) {
        foreach (var NextFile in TheFolder.GetFiles("*.lua")) {
            var utf8WithoutBom = new System.Text.UTF8Encoding(false);
            StreamReader sr = new StreamReader(NextFile.FullName, utf8WithoutBom);
            string text = sr.ReadToEnd();
            FileStream fs = new FileStream(path + "/" + Path.ChangeExtension(NextFile.Name, "txt"), FileMode.Create);
            StreamWriter sw = new StreamWriter(fs, utf8WithoutBom);
            sw.Write(text);

            sr.Close();

            sw.Flush();
            sw.Close();
            fs.Close();
        }
        foreach (DirectoryInfo NextFolder in TheFolder.GetDirectories()) {
            ChangeLua2Txt(NextFolder, path);
        }
    }
    static private void DeleteTxt(DirectoryInfo TheFolder) {
        foreach (var NextFile in TheFolder.GetFiles("*.txt")) {
            NextFile.Delete();
        }
        foreach (DirectoryInfo NextFolder in TheFolder.GetDirectories()) {
            DeleteTxt(NextFolder);
        }
    }
}