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);
}