Cordova Background转移到更新应用程序

Question

我的目的是执行后台传输以更新我的android cordova应用程序。 我正在尝试从我的网络服务器下载apk，然后我想使用WebIntent插件来启动应用更新。

然而，当我启动下载系统时出现错误“错误不支持的路径/data/user/0/io.cordova.myapp88c1a0/files/files/newpackage.apk”

以下是代码，真正感谢任何帮助：

function  downloadFile(uriString, targetFile) {

    var complete = function() {
        alert('Done');
    };
    var error = function (err) {
        console.log('Error: ' + err);
        alert('error ' + err);
    };
    var progress = function (p)
    {
        console.log(p);

    }

    try {

        var downloader = new BackgroundTransfer.BackgroundDownloader();
        // Create a new download operation.
        var download = downloader.createDownload(uriString, targetFile);
        // Start the download and persist the promise to be able to cancel the download.
        var promise = download.startAsync().then(complete, error, progress);

    } catch(err) {
        console.log('Error: ' + err);
    }
};

function startDownload () {
    alert('start download');

    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function (fileSystem) {

        fileSystem.root.getFile(fileName, { create: true }, function (newFile) {
            alert(uriString);
            alert(newFile);
            downloadFile(uriString, newFile);
        });
    },
    function (e)
    {
        var msg = '';

        switch (e.code) {
            case FileError.QUOTA_EXCEEDED_ERR:
                msg = 'QUOTA_EXCEEDED_ERR';
                break;
            case FileError.NOT_FOUND_ERR:
                msg = 'NOT_FOUND_ERR';
                break;
            case FileError.SECURITY_ERR:
                msg = 'SECURITY_ERR';
                break;
            case FileError.INVALID_MODIFICATION_ERR:
                msg = 'INVALID_MODIFICATION_ERR';
                break;
            case FileError.INVALID_STATE_ERR:
                msg = 'INVALID_STATE_ERR';
                break;
            default:
                msg = 'Unknown Error';
                break;
        };

        alert('Error: ' + msg);
    }
    );
}