Unity3d热更新之下载

著热更新框架：uluaFramework_UIGUI-master，在Unity热更新时，先释放资源（StreamingAssets --> DataPath），再从服务端下载资源（或者其它下载网络文件的时候）

（1）下载方案

启动一个线程，每隔几毫秒询问队列，队列中下载Action数大于0，则开启WebClient异步下载

（2）问题

（1）用windows自带的iis搭建的web服务，在下载资源时始终下载不下来，但又没有异常提示。luaFramework使用WebClient.DownloadFileAsync时，若下载发生异常，并没有做异常处理

解决办法：

WebClient异步下载时，tryCatch捕捉不到异常，需要在WebClient.DownloadFileComplete回调中捕捉

（2）本地目录错误时，依然捕捉不到异常

（3）.net的一些封装库有时并不可靠，正式项目时需要改用其它下载方案或用TCP自己实现

/// <summary>
/// 下载任务
/// </summary>
public class DownloadAction
{
    /// <summary>
    /// 下载Action编号
    /// </summary>
    public string id;
    /// <summary>
    /// 下载远程url、本地url
    /// </summary>
    public List<string> actionParams = new List<string>();

    public DownloadAction(string id, string fileName, string localPath, string remoteUrl)
    {
        this.id = id;
        List<string> actionParams = new List<string>();
        actionParams.Add(fileName);
        actionParams.Add(localPath);
        actionParams.Add(remoteUrl);
        this.actionParams = actionParams;
    }
}

public class DownloadManager : MonoBehaviour
{
    public Thread queryThread;
    public Queue<DownloadAction> actionQueue = new Queue<DownloadAction>();

    /// <summary>
    /// WebClient集合，用于释放内存
    /// </summary>
    private List<WebClient> clientList = new List<WebClient>();

    /// <summary>
    /// 计时器
    /// </summary>
    Stopwatch sw = new Stopwatch();

    static readonly object lockObject = new object();

    void Start()
    {
        queryThread = new Thread(OnUpdate);
        queryThread.Start();

        //添加两个下载任务
        string locaPath1 = "e:/StreamingAssets/a.jpg";
        string remoteUrl1 = "http://localhost:8080/manager/StreamingAssets/a.jpg";
        DownloadAction action1 = new DownloadAction("111", "a.jpg", locaPath1, remoteUrl1);
        actionQueue.Enqueue(action1);

        string locaPath2 = "e:/StreamingAssets/zhangwuji.mp4";
        string remoteUrl2 = "http://localhost:8080/manager/StreamingAssets/zhangwuji.mp4";
        DownloadAction action2 = new DownloadAction("222", "zhangwuji.mp4", locaPath2, remoteUrl2);
        actionQueue.Enqueue(action2);

    }

    void OnUpdate()
    {
        while (true)
        {
            lock (lockObject)
            {
                if (actionQueue.Count > 0)
                {
                    DownloadAction action = actionQueue.Dequeue();
                    DownloadFile(action);

                    Debug.Log("开始下载文件：" + action.actionParams[0]);
                    Debug.Log("本地地址：" + action.actionParams[1]);
                    Debug.Log("远程地址：" + action.actionParams[2]);
                }
            }
            Thread.Sleep(10);
        }
    }

    /// <summary>
    /// 下载文件
    /// </summary>
    /// <param name="action">下载任务</param>
    private void DownloadFile(DownloadAction action)
    {
        //url
        string localPath = action.actionParams[1].ToString();
        string remoteUrl = action.actionParams[2].ToString();

        WebClient client = new WebClient();
        clientList.Add(client);

        //sw.Start();   //计时器，可以用于计算下载速度
        client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(DownloadProcesChange);
        client.DownloadFileCompleted += new AsyncCompletedEventHandler(DownloadComplete);
        client.DownloadFileAsync(new Uri(remoteUrl), localPath);
    }

    /// <summary>
    /// 异常处理回调
    /// </summary>
    private void DownloadComplete(object sender, AsyncCompletedEventArgs e)
    {
        if (e.Error != null)
        {
            Debug.LogError(e.Error.Message);
            MemoryRelease();
        }
    }

    /// <summary>
    /// 下载回调
    /// </summary>
    private void DownloadProcesChange(object sender, DownloadProgressChangedEventArgs e)
    {
        string received = (e.BytesReceived / (1024d * 1024d)) + "";
        Debug.Log("接收文件大小：" + received + "M");
        if (e.ProgressPercentage == 100 && e.BytesReceived == e.TotalBytesToReceive)
        {
            Debug.Log("下载完成");
            ((WebClient)sender).CancelAsync();
            ((WebClient)sender).Dispose();
        }
    }

    void OnApplicationQuit()
    {
        MemoryRelease();
    }

    /// <summary>
    /// 内存释放
    /// </summary>
    void MemoryRelease()
    {
        for (int i = 0; i < clientList.Count; i++)
        {
            clientList[i].CancelAsync();
            clientList[i].Dispose();
        }
    }
}