5.下载器-Download

GameFramework下载器Download

类图

使用

先在 DownloadComponent 中配置:

• Download Agent Helper Count 下载器数量

    public class TestDownload
    {
        static int s_downloadId;
        public static void Test()
        {
            Game.Event.Subscribe(DownloadStartEventArgs.EventId, OnDownloadStart);
            Game.Event.Subscribe(DownloadUpdateEventArgs.EventId, OnDownloadUpdate);
            Game.Event.Subscribe(DownloadSuccessEventArgs.EventId, OnDownloadSuccess);
            Game.Event.Subscribe(DownloadFailureEventArgs.EventId, OnDownloadFailure);

            DownloadComponent downloadComponent = GameEntry.GetComponent<DownloadComponent>();
            s_downloadId = downloadComponent.AddDownload(Path.Combine(Application.persistentDataPath,"1.txt")
                , "http://myname.com/data/1.txt"
                , userData: "mydown");  //  userData 可以关联你自己的数据
        }

        private static void OnDownloadSuccess(object sender, GameEventArgs e)
        {
            //  下载成功
            DownloadSuccessEventArgs args = (DownloadSuccessEventArgs)e;

            //  有2种方式判断这个下载是不是你要的下载
            //  1. GameFramework内置方式，通过 SerialId 判断
            if ( args.SerialId != s_downloadId )
                return ;

            //  2. 你在用户数据中传递一个唯一的索引进行判断
            if ( !(args.UserData is string name && name == "mydown") )
                return ;
            

        }

        private static void OnDownloadFailure(object sender, GameEventArgs e)
        {
            DownloadFailureEventArgs args = (DownloadFailureEventArgs)e;
            //  判断是否你的下载，同 OnDownloadSuccess
            Debug.Log(args.ErrorMessage);
        }

        private static void OnDownloadStart(object sender, GameEventArgs e)
        {
            DownloadStartEventArgs args = (DownloadStartEventArgs)e;
        }

        private static void OnDownloadUpdate(object sender, GameEventArgs e)
        {
            DownloadUpdateEventArgs args = (DownloadUpdateEventArgs)e;
            //  一般用来更新进度条，可是 args 只提供 CurrentLength 表示当前大小，没有总大小
        }
    }

流程分析

DownloadManager 管理下载，往 TaskPool<DownloadTask> 中添加下载任务 DownloadTask
TaskPool<DownloadTask> 负责找到空闲的下载器 DownloadAgent 来下载 DownloadTask
DownloadAgent 把具体的下载任务委托给  DownloadAgentHelperBase 去下载 
UnityWebRequestDownloadAgentHelper 是 DownloadAgentHelperBase 的一个默认实现，把下载任务委托给 UnityWebRequest

下载代码分析

    //  初始化下载器
    DownlaodComponent.Start()
    {
        for (int i = 0; i < m_DownloadAgentHelperCount; i++)
        {
            AddDownloadAgentHelper(i)
            {
                //  这里创建的是 UnityWebRequestDownloadAgentHelper
                DownloadAgentHelperBase downloadAgentHelper = Helper.CreateHelper(m_DownloadAgentHelperTypeName, m_CustomDownloadAgentHelper, index);
                m_DownloadManager.AddDownloadAgentHelper(downloadAgentHelper)   //  DownloadManager.AddDownloadAgentHelper
                {
                    DownloadAgent agent = new DownloadAgent(downloadAgentHelper);
                    agent.DownloadAgentStart += OnDownloadAgentStart;
                    agent.DownloadAgentUpdate += OnDownloadAgentUpdate;
                    agent.DownloadAgentSuccess += OnDownloadAgentSuccess;
                    agent.DownloadAgentFailure += OnDownloadAgentFailure;

                    m_TaskPool.AddAgent(agent)
                    {
                        agent.Initialize();
                        m_FreeAgents.Push(agent);   //  加入空闲队列中
                    }
                }
            }
        }
    }

    //  添加下载任务
    DownlaodComponent.AddDownload(string downloadPath, string downloadUri)
    {
        return m_DownloadManager.AddDownload(downloadPath, downloadUri, tag, priority, userData)    //  DownloadManager.AddDownload
        {
            DownloadTask downloadTask = DownloadTask.Create(downloadPath, downloadUri, tag, priority, m_FlushSize, m_Timeout, userData);
            m_TaskPool.AddTask(downloadTask)    //  TaskPool<DownloadTask>.AddTask
            {
                m_WaitingTasks.AddAfter(current, task);     //  任务加入等待队列
            }
            return downloadTask.SerialId;
        }
    }

    //  执行下载任务
    DownloadManager.Update(float elapseSeconds, float realElapseSeconds)
    {
        m_TaskPool.Update(elapseSeconds, realElapseSeconds)     //  TaskPool<DownloadTask>.Update
        {
            ProcessRunningTasks(elapseSeconds, realElapseSeconds)
            {
                DownloadAgent taskAgent = m_WorkingAgents.First;
                taskAgent.Update(elapseSeconds, realElapseSeconds)
                {
                   //   判断正在下载的任务是否超时
                }
            }
            ProcessWaitingTasks(elapseSeconds, realElapseSeconds)   //  TaskPool<DownloadTask>.ProcessWaitingTasks
            {
                LinkedListNode<DownloadTask> current = m_WaitingTasks.First;    //  从等待列表中取出第1个任务
                DownloadTask task = current.Value; 

                ITaskAgent<DownloadTask> agent = m_FreeAgents.Pop();            //  获得空闲下载任务执行器
                LinkedListNode<ITaskAgent<DownloadTask>> agentNode = m_WorkingAgents.AddLast(agent);    //  加入执行器列表中

                StartTaskStatus status = agent.Start(task); //  用执行器下载任务
            }
        }
    }