游戏内容变更之后。一般而言不会想让玩家下载整个游戏包又一次安装，由于这样会流失大量玩家。全部游戏更新是必须的。

更新的内容包含 数据、资源、代码。

基本原理：

1、将须要更新的文件打包成AssetBundle文件，并计算各个文件的crc值。

以下代码将选择的文件分别导出为AssetBundle文件，并将每一个文件的crc值写入到crc.txt文件里，在Editor文件夹建立一个类，并复制以下代码。

能够在Project文件夹导出选择的文件。

public class ExportAssetBundles {

[MenuItem("Assets/Build AssetBundle From Selection Respective -  Track dependencies")]

static void ExportResourceRespective()

{

// Bring up save panel

string path = EditorUtility.SaveFilePanel ("Save Resource", "", "New Resource", "unity3d");

string dirpath = path.Substring(0,path.LastIndexOf("/")+1);

string filename = path.Substring(path.LastIndexOf("/")+1);

if (path.Length != 0) {

#if UNITY_ANDROID

string targetDir = "Android/";

BuildTarget targetBuild = BuildTarget.Android;

#elif UNITY_IPHONE

string targetDir = "iPhone/";

BuildTarget targetBuild = BuildTarget.iPhone;

#elif UNITY_STANDALONE_WIN

string targetDir = "StandaloneWindows/";

BuildTarget targetBuild = BuildTarget.StandaloneWindows;

#endif

JSDocument.JSNode node = new JSDocument.JSNode("root");

Document.SNode[] nodes = node.putChildren("filehash",Selection.objects.Length);

for(int i=0;i<Selection.objects.Length;i++)

{

string name = Selection.objects[i].name+".unity3d";

uint crc = 0;

if(!Directory.Exists(dirpath+targetDir))

Directory.CreateDirectory(dirpath+targetDir);

BuildPipeline.BuildAssetBundle(Selection.objects[i],new Object[]{ Selection.objects[i]}, dirpath+targetDir+name,out crc,BuildAssetBundleOptions.CollectDependencies,targetBuild);

nodes[i].put("name",name);

nodes[i].put("crc",crc);

}

System.IO.File.WriteAllText(dirpath+targetDir+filename+".crc.txt",node.toJSONString());

}

}

}

2.须要一个资源更新server，将导出的AssetBundle文件和crc文件上传到资源更新server。能够用一个简单的httpserver。比如nginx。

3.client进入游戏之前。首先向更新server请求crc.txt文件。然后从本地的磁盘文件夹中查找crc.txt文件，检查须要更新的文件列表。然后从server下载须要更新的文件。这样，假设server没有更改文件，则仅仅须要下载一次。

4.最新的crc.txt文件到本地，以便下次查询。

以下代码演示 3,4 步骤，当中

Engine.Instance.server_datapath = 服务器下载地址。

Engine.Instance.local_datapath = Application.persistentDataPath+"/;

public static IEnumerator  UpdateDataFromServer(UpdateProgress up)

{

string server_datapath = Engine.Instance.server_datapath;

string local_datapath = Engine.Instance.local_datapath;

byte[] server_crc_data  = null;

Dictionary filehash_server=new Dictionary();

Dictionary  filehash_local=new Dictionary();

List needUpdateFile = new List();

Debug.Log("Load Server FileHash");

using(WWW www = new WWW(server_datapath+"crc.txt"))

{

yield return www;

if (!String.IsNullOrEmpty(www.error))

{

Debug.Log("Load Filehash Failed");

up(1.0f);

yield break;

}

JSDocument.JSNode node = new JSDocument.JSNode("filehash",www.text);

Document.SNode[] data = node.getChildren("filehash");

for(int i=0;i<data.Length;i++)

{

filehash_server[data[i].get("name","")] = data[i].get("crc",(long)0);

}

server_crc_data = www.bytes;

}

Debug.Log("Load Local FileHash");

//从本地载入文件MD5表。可能没有

try

{

JSDocument.JSNode node = new JSDocument.JSNode("filehash",System.IO.File.ReadAllText(local_datapath+"crc.txt"));

Document.SNode[] data = node.getChildren("filehash");

for(int i=0;i<data.Length;i++)

{

filehash_local[data[i].get("name","")] = data[i].get("crc",(long)0);

}

}

catch(Exception e)

{

Debug.Log(e.Message);

}

Debug.Log("Check FileHash");

//计算须要更新的文件

foreach(KeyValuePair data in filehash_server)

{

//更新须要的文件

if(!filehash_local.ContainsKey(data.Key) || filehash_local[data.Key] != data.Value)

{

needUpdateFile.Add(data.Key);

}

}

Debug.Log("Update File");

//下载并存储

for(int i=0;i<needUpdateFile.Count;i++)

{

using(WWW www = new WWW(server_datapath+needUpdateFile[i]))

{

yield return www;

byte[] bytes = null;

if (!String.IsNullOrEmpty(www.error))

{

Debug.Log(www.error);

yield break;

}

else

{

bytes = www.bytes;

}

up((float)i/needUpdateFile.Count);

string path = local_datapath+ needUpdateFile[i];

Debug.Log(path);

FileStream fs = new FileStream(path,FileMode.Create);

fs.Write(bytes,0,bytes.Length);

fs.Flush();

fs.Close();

//              //保存

//              BinaryWriter writer;

//              FileInfo t =new FileInfo(local_datapath+ needUpdateFile[i]);

//                if(!t.Exists)

//              {

//                  writer = new BinaryWriter(t.Open(FileMode.OpenOrCreate));

//              }

//              else

//              {

//                  t.Delete();

//                  writer = new BinaryWriter(t.Open(FileMode.Create));

//              }

//              writer.Write(bytes);

//              writer.Close();

}

}

Debug.Log("Save FileHash");

if(needUpdateFile.Count>0)

{

//保存最新的文件MD5值表

//          FileStream fs = new FileStream(local_datapath+"crc.txt",FileMode.Create);

//          fs.Write(server_crc_data,0,server_crc_data.Length);

//          fs.Flush();

//            fs.Close();

BinaryWriter writer;

FileInfo t =new FileInfo(local_datapath+"crc.txt");

if(!t.Exists)

{

writer = new BinaryWriter(t.Open(FileMode.Create));

}

else

{

t.Delete();

writer = new BinaryWriter(t.Open(FileMode.Create));

}

writer.Write(server_crc_data);

writer.Close();

Debug.Log(local_datapath+"crc.txt");

}

}

5.载入已经更新完毕的存储在本地的AssetBundle，须要注意的是。Unity3d同样的文件同一时候仅仅能有一个AssetBundle在内存中，所以我们对于同样文件的载入做了同步。

(loadRefCount)。

static HashSet loadRefCount = new HashSet();

public delegate void delegateLoadFinish(GameObject go);

public static IEnumerator LoadModel(string res,delegateLoadFinish onLoadFinish)

{

GameObject resObject = Resources.Load("cards/"+res);

if(resObject !=null)

{

onLoadFinish((GameObject)GameObject.Instantiate(resObject));

yield break;

}

//假设包括资源。返回

while(loadRefCount.Contains(res))

{

yield return true;

}

loadRefCount.Add(res);

Debug.Log(Engine.Instance.local_datapath+res+".unity3d");

AssetBundleCreateRequest crcLocalBundle = AssetBundle.CreateFromMemory(

System.IO.File.ReadAllBytes(Engine.Instance.local_datapath+res+".unity3d"));

yield return crcLocalBundle;

{

GameObject cardObject = GameObject.Instantiate(crcLocalBundle.assetBundle.mainAsset)as GameObject;

crcLocalBundle.assetBundle.Unload(false);

onLoadFinish(cardObject);

}

loadRefCount.Remove(res);

}