Unity游戏内版本更新

最近研究了一下游戏内apk包更新的方法。

ios对于应用的管理比较严格，除非热更新脚本，不太可能做到端内大版本包的更新。然而安卓端则没有此限制。因此可以做到不跳到网页或应用商店，就覆盖更新apk包。

Unity最常用的脚本语言就是C#，不做断点续传的情况下，采用C#的网络库，还是比较简单的。重点就是做好相应的异常处理。

C#用于网络访问的方法主要有两种：WebRequest和封装好的WebClient。为了将来能做更多的扩展，我采用更灵活的HttpWebRequest进行请求。为了不阻塞主线程，使用异步接口。

基本做法可参考官方文档https://msdn.microsoft.com/zh-cn/library/system.net.httpwebrequest.begingetresponse(v=vs.110).aspx

然而我们知道，Unity4.X对于多线程的支持是很弱的，不推荐使用。因此，无法在下载线程中回调相应的事件。我将回调写在主线程中，用Coroutine去轮询当前的下载状态和进度，并做相应的处理。

首先需要定义下载的状态和传入下载线程的请求状态，然后是下载的路径(可能还需要文件MD5码)以及安装路径等必要的变量，最后为了显示当前的下载进度、下载速度等，需要开启一个Coroutine或者在Update中不断查询当前下载状态，是否有异常，以及是否已经下载完毕。如果下载完毕，则校验文件，并开始安装。

 using UnityEngine;
 using System;
 using System.Collections;
 using System.Threading;
 using System.IO;
 using System.Net;
 using System.Security.Cryptography;
 using System.Text;
 using System;

 public class VersionUpdater : MonoBehaviour
 {
     public class RequestState
     {
         public const int BUFFER_SIZE = ;
         public byte[] BufferRead;
         public HttpWebRequest request;
         public HttpWebResponse response;
         public Stream responseStream;
     }

     public enum DownloadState
     {
         DOWNLOADING,
         FINISHED,
         FAILED
     }

     public delegate void ProgressCallback(long curr, long length, float rate, DownloadState state);
     public ProgressCallback progressCallback;

     string url = "";
     string installPath = "";
     string apkName = "";
     string errorMsg = "";

     private FileStream fileStream = null;
     private long length = ;
     private long curr = ;
     private long last = ;
     private const float UpdateTime = 0.5f;
     private float rate = ;
     private DownloadState downState = DownloadState.DOWNLOADING;

     public void DownloadApkAsync(string url, string md5, string path, string name)
     {
         this.url = url;
         this.installPath = path;
         this.apkName = name;
         this.errorMsg = "";
         downState = DownloadState.DOWNLOADING;

         DownloadApkAsync();
     }

     private void DownloadApkAsync()
     {
         if (string.IsNullOrEmpty(url)) return;
         if (string.IsNullOrEmpty(installPath)) return;
         if (string.IsNullOrEmpty(apkName)) return;

         string fullpath = installPath + "/" + apkName;

         IAsyncResult result = null;
         try
         {
             fileStream = new FileStream(fullpath, FileMode.Create, FileAccess.Write);

             Uri uri = new Uri(url);
             HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

             request.Method = "GET";

             RequestState requestState = new RequestState();
             requestState.BufferRead = new byte[RequestState.BUFFER_SIZE];
             requestState.request = request;

             curr = ;
             length = ;
             rate = 0.0f;
             downState = DownloadState.DOWNLOADING;
             result = (IAsyncResult)request.BeginGetResponse(new AsyncCallback(ResponeCallback), requestState);
         }
         catch (Exception e)
         {
             errorMsg = "Begin Create Exception!";
             errorMsg += string.Format("Message:{0}", e.Message);
             StopDownload(result);
             downState = DownloadState.FAILED;
         }

         StartCoroutine(updateProgress());
     }

     IEnumerator updateProgress()
     {
         while (curr <= length)
         {
             yield return new WaitForSeconds(UpdateTime);

             rate = (curr - last) / UpdateTime;
             last = curr;

             if (downState == DownloadState.FAILED)
             {
                 Debug.LogError(errorMsg);
                 if (fileStream != null)
                     fileStream.Close();
                 if (progressCallback != null)
                     progressCallback( curr, length, rate, DownloadState.FAILED);
                 break;
             }

             if (progressCallback != null)
                 progressCallback( curr, length, rate, DownloadState.DOWNLOADING);

             if (downState == DownloadState.FINISHED)
             {
                 if (progressCallback != null)
                     progressCallback( curr, length, rate, DownloadState.FINISHED);
                 break;
             }
         }
     }

     void StopDownload(IAsyncResult result)
     {
         if (result == null) return;
         RequestState requestState = (RequestState)result.AsyncState;
         requestState.request.Abort();
     }

     void ResponeCallback(IAsyncResult result)
     {
         try
         {
             if (downState != DownloadState.FAILED)
             {
                 RequestState requestState = (RequestState)result.AsyncState;
                 HttpWebRequest request = requestState.request;
                 requestState.response = (HttpWebResponse)request.EndGetResponse(result);

                 Stream responseStream = requestState.response.GetResponseStream();
                 requestState.responseStream = responseStream;

                 length = requestState.response.ContentLength;

                 IAsyncResult readResult = responseStream.BeginRead(requestState.BufferRead, , RequestState.BUFFER_SIZE, new AsyncCallback(ReadCallback), requestState);
                 return;
             }
         }
         catch (Exception e)
         {
             string msg = "ResponseCallback exception!\n";
             msg += string.Format("Message:{0}", e.Message);
             StopDownload(result);
             errorMsg = msg;
             downState = DownloadState.FAILED;
         }
     }

     void ReadCallback(IAsyncResult result)
     {
         try
         {
             if (downState != DownloadState.FAILED)
             {
                 RequestState requestState = (RequestState)result.AsyncState;
                 Stream responseStream = requestState.responseStream;
                 int read = responseStream.EndRead(result);
                 if (read > )
                 {
                     fileStream.Write(requestState.BufferRead, , read);
                     fileStream.Flush();
                     curr += read;

                     IAsyncResult readResult = responseStream.BeginRead(requestState.BufferRead, , RequestState.BUFFER_SIZE, new AsyncCallback(ReadCallback), requestState);
                     return;
                 }
                 else
                 {
                     Debug.Log("download end");
                     responseStream.Close();
                     fileStream.Close();

                     downState = DownloadState.FINISHED;
                 }
             }
         }
         catch (Exception e)
         {
             string msg = "ReadCallBack exception!";
             msg += string.Format("Message:{0}", e.Message);
             StopDownload(result);
             errorMsg = msg;
             downState = DownloadState.FAILED;
         }
     }

     public void InstallApk()
     {
 #if UNITY_ANDROID && !UNITY_EDITOR
         Debug.Log("begin install");
         using (AndroidJavaObject jo = new AndroidJavaObject("com.kevonyang.androidhelper.AndroidHelper"))
         {
             if (jo == null)
             {
                 WMDebug.Debug.LogError("VersionUpdater: Failed to get com.kevonyang.androidhelper.AndroidHelper");
                 return;
             }
             using (AndroidJavaClass jc = new AndroidJavaClass("com.unity3d.player.UnityPlayer"))
             {
                 if (jc == null)
                 {
                     WMDebug.Debug.LogError("VersionUpdater: Failed to get com.unity3d.player.UnityPlayer");
                     return;
                 }
                 AndroidJavaObject m_jo = jc.GetStatic<AndroidJavaObject>("currentActivity");
                 if (m_jo == null)
                 {
                     WMDebug.Debug.LogError("VersionUpdater: Failed to get currentActivity");
                     return;
                 }

                 jo.CallStatic("InstallApk", m_jo, installPath, apkName);
             }
         }
 #endif
     }
 }

在下载完毕后，需要写一个java类，并在里面调用安装接口。内容很简单，只需要简单的启动一个安装的Intent就可以了，随后就会出现系统提示，是否覆盖安装。至此，游戏内的下载及安装全部完成，等待覆盖安装完毕即可从新的客户端启动。

     public static void InstallApk(Context context, String path, String name) {
         Intent intent = new Intent(Intent.ACTION_VIEW);
         intent.setDataAndType(Uri.fromFile(new File(path, name)), "application/vnd.android.package-archive");
         context.startActivity(intent);
     }