如何使用 URLSession 下载视频，在 appcelerator titanium 中保存和播放？

Question

我正在尝试使用 URLSession 下载并保存视频，然后在视频播放器中播放。但不知何故它没有播放，而是使应用程序崩溃。这是 it.I 的代码已经尝试了几乎所有方法来使用 nativePath、getNativePath()、file.resolve() 读取文件的确切路径，但似乎没有任何效果。查看代码并提出解决方案。这是为了 iOS。（iOS 版本 8.4）

更新代码：

    var args = arguments[0] || {};

    var vidWin = $.winTestVideo;
    var isDownloading = false;

    var urlSession = require("com.appcelerator.urlSession");
    var downloadSession;

    var urlArray = ["http://www.kaltura.com/p/{PARTNERID}/sp/{SUBPARTNERID}/playManifest/entryId/{entryId}/format/applhttp/protocol/http/flavorId/{flavorId}/video.mp4",
"http://www.kaltura.com/p/{PARTNERID}/sp/{SUBPARTNERID}/playManifest/entryId/{entryId}/format/applhttp/protocol/http/flavorId/{flavorId}/video.mp4"];

    var urlArrIndex = 0;
    var progress;
    var videoPlayer;
    var imageUrl = 'http://dreamatico.com/data_images/rose/rose-4.jpg';
    //'http://cdn.playbuzz.com/cdn/5d41f0c6-2688-47fe-85cf-82890ef6d91d/45611be8-42f9-4d02-9b63-f7195c0dc18c_560_420.jpg';
    var img;
    function onLoad() {
        Alloy.Globals.CurrentWindowName = 'testvideoplayer';
        var triggerBtn = Ti.UI.createButton({
            top : 10,
            width : Ti.UI.FILL,
            height : 40,
            backgroundColor : "#cccccc",
            color : "#000000",
            title : "Download Videos"
        });
        vidWin.add(triggerBtn);
        triggerBtn.addEventListener('click', downloadVideoBackround2);

        progress = Titanium.UI.createProgressBar({
            width : 200,
            height : 20,
            min : 0,
            max : 1,
            value : 0,
            top : 60,
            backgroundColor : "#0000ff",
            style : Ti.UI.iPhone.ProgressBarStyle.BAR,

        });

        vidWin.add(progress);

        img = Ti.UI.createImageView({
            width : 100,
            height : 100,
            backgroundColor : "#cccccc"
        });
        //vidWin.add(img);

        //videoPlayer.play();

    }

    function createVideoPlayer() {
        videoPlayer = Ti.Media.createVideoPlayer({
            width : Ti.UI.FILL,
            height : 240,
            top : 100,
            mediaControlStyle : Titanium.Media.VIDEO_CONTROL_DEFAULT,
            scalingMode : Titanium.Media.VIDEO_SCALING_ASPECT_FIT,
            backgroundColor : "#000000",

        });
        vidWin.add(videoPlayer);
        videoPlayer.removeEventListener('playbackstate', playbackStateEventListener);
        videoPlayer.addEventListener('playbackstate', playbackStateEventListener);
    }

    // Require in the urlSession module
    var urlSession = require("com.appcelerator.urlSession");
    var session;
    // App UI

    function playbackStateEventListener(evt) {
        Ti.API.error("PlaybackStateEventListener  : " + JSON.stringify(evt));
    }

    function downloadVideoBackround2(evt){
        // Create a session configuration
        // The string parameter is an arbitrary string used to identify the session in events
        var sessionConfig = urlSession.createURLSessionBackgroundConfiguration("com.appcelerator.test");
        // Create a session
        session = urlSession.createURLSession(sessionConfig);
        // Create a background download task to get the asset with the URL
        urlSession.backgroundDownloadTaskWithURL(session,urlArray[0].replace('applhttp','url'));
        progress.show();
    }

    // Monitor this event to receive updates on the progress of the download
    Ti.App.iOS.addEventListener("downloadprogress", function(e) {
        // Update the progress indicator
        Ti.API.error("DOWNLOAD PROGRESS : " + e.totalBytesWritten + "/" + e.totalBytesExpectedToWrite);
        progress.value = (e.totalBytesWritten / e.totalBytesExpectedToWrite);
    });

    // Monitor this event to know when the download completes
    Ti.App.iOS.addEventListener("downloadcompleted", function(e) {
        Ti.API.error("download completed " + JSON.stringify(e));
        // Update the image
        try {

            var file = Titanium.Filesystem.getFile(Titanium.Filesystem.applicationDataDirectory, 'myplvideo.mp4');
            if (!file.exists()) {
                file.createFile();
            }
            file.write(e.data);
            Ti.API.error('data : ' + e.data.length);
            Ti.API.error('file : ' + file.nativePath);
            Ti.API.error('file resolve path :' + file.resolve());
            progress.hide();

            // Notify the user the download is complete if the application is in the background
            setTimeout(function() {

                //videoPlayer.media = file;
                createVideoPlayer();
                videoPlayer.media = file;
                urlSession.finishTasksAndInvalidate(session);
                //videoPlayer.play();
            }, 3000);

            //alert('Download completed!');
            /*
             Ti.App.iOS.scheduleLocalNotification({
             alertAction : "update",
             // Alert will display the following message
             alertBody : "Download was successfull",
             // The badge value in the icon will be changed to 1
             badge : 1,
             // Alert will be sent in three seconds
             date : new Date(new Date().getTime() + 3000),
             });*/

        } catch(ex) {
            Ti.API.error('download completed : ' + ex);
        }
    });
    // Monitor this event to know when all session tasks have completed
    Ti.App.iOS.addEventListener('sessioncompleted', function(e) {
        try {

            Ti.API.error("sessioncompleted " + JSON.stringify(e));
            if (e.success) {
                //alert("Downloads completed successfully.");
            }
        } catch(ex) {
            Ti.API.error('Exception session completed : ' + ex);
        }
    });

当我将 file 分配给 videoPlayer 的 media 属性时，应用程序崩溃了。但是当我使用 HttpClient 下载文件时，它工作正常。不太确定为什么会这样，因为我在日志中看不到任何错误。

这是日志。我已经使用 [Error] 来突出显示重要的日志记录。

[ERROR] :  DOWNLOAD PROGRESS : 67470/5794757
[ERROR] :  DOWNLOAD PROGRESS : 133006/5794757
[ERROR] :  DOWNLOAD PROGRESS : 199614/5794757
[ERROR] :  DOWNLOAD PROGRESS : 266222/5794757
[ERROR] :  DOWNLOAD PROGRESS : 275982/5794757
[ERROR] :  DOWNLOAD PROGRESS : 341518/5794757
[ERROR] :  DOWNLOAD PROGRESS : 408126/5794757
[ERROR] :  DOWNLOAD PROGRESS : 474734/5794757
[ERROR] :  DOWNLOAD PROGRESS : 541342/5794757
[ERROR] :  DOWNLOAD PROGRESS : 609398/5794757
[ERROR] :  DOWNLOAD PROGRESS : 677454/5794757
[ERROR] :  DOWNLOAD PROGRESS : 745510/5794757
[ERROR] :  DOWNLOAD PROGRESS : 758166/5794757
[ERROR] :  DOWNLOAD PROGRESS : 823702/5794757
[ERROR] :  DOWNLOAD PROGRESS : 897550/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1048142/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1114750/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1182806/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1249414/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1316022/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1382630/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1385150/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1450686/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1518742/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1586798/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1653406/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1720014/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1786622/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1854678/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1921286/5794757
[ERROR] :  DOWNLOAD PROGRESS : 1989342/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2057398/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2059918/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2125454/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2205094/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2271702/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2341206/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2342278/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2407814/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2410334/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2475870/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2542478/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2609086/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2675694/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2676766/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2742302/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2808910/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2876966/5794757
[ERROR] :  DOWNLOAD PROGRESS : 2943574/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3010182/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3076790/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3143398/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3212902/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3274790/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3340326/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3422862/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3557526/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3624134/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3692190/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3758798/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3825406/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3893462/5794757
[ERROR] :  DOWNLOAD PROGRESS : 3960070/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4026678/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4094734/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4161342/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4227950/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4294558/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4362614/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4430670/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4497278/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4498350/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4563886/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4630494/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4697102/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4699622/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4765158/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4831766/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4898374/5794757
[ERROR] :  DOWNLOAD PROGRESS : 4964982/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5031590/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5098198/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5106510/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5172046/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5319742/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5320814/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5386350/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5455854/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5523910/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5591966/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5658574/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5726630/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5794686/5794757
[ERROR] :  DOWNLOAD PROGRESS : 5794757/5794757
[ERROR] :  download completed {"taskIdentifier":1,"data":{},"bubbles":true,"type":"downloadcompleted","source":{},"cancelBubble":false}
[ERROR] :  open on /var/mobile/Containers/Data/Application/9FBAAEB4-4878-4611-8BCC-EFC112AF9777/Documents/myplvideo.mp4: File exists
[ERROR] :  data : 5794757
[ERROR] :  file : file:///var/mobile/Containers/Data/Application/9FBAAEB4-4878-4611-8BCC-EFC112AF9777/Documents/myplvideo.mp4
[ERROR] :  file resolve path :/var/mobile/Containers/Data/Application/9FBAAEB4-4878-4611-8BCC-EFC112AF9777/Documents/myplvideo.mp4
[ERROR] :  sessioncompleted {"success":true,"message":"","errorCode":0,"taskIdentifier":1,"bubbles":true,"type":"sessioncompleted","source":{},"cancelBubble":false}

Answer 1

我的快速猜测是您有竞争条件。在你的 setTimeout 中，你从来没有真正检查文件是否已经被写入，就像你完成下载时所做的那样，假设此时 3s 足够长。

// Notify the user the download is complete if the application is in the background
setTimeout(function() {
  //videoPlayer.media = file;
  createVideoPlayer();
  videoPlayer.media = file;
  urlSession.finishTasksAndInvalidate(session);
  //videoPlayer.play();
}, 3000);

此外，设备或模拟器的 xcode 日志应该告诉您 where/what 崩溃（这些可能并不总是出现在钛日志中）

如何使用 URLSession 下载视频，在 appcelerator titanium 中保存和播放？

how to download video using URLSession, save and play it in appcelerator titanium?

appcelerator-mobile

ios

titanium-modules

titanium-alloy

nsurlsession