【WP开发】在手机屏幕点亮时播放声音

    public sealed class Back:IBackgroundTask
    {
        BackgroundTaskDeferral deferral = null;
        public async void Run ( IBackgroundTaskInstance taskInstance )
        {
            deferral = taskInstance.GetDeferral();
            Uri media = new Uri("ms-appx:///1.mp3");
            // 打开文件流
            StorageFile file = await StorageFile.GetFileFromApplicationUriAsync(media);
            var stream = await file.OpenReadAsync();
            // 获取播放器控制对象
            MediaPlayer player = BackgroundMediaPlayer.Current;
            player.AutoPlay = true; //设置自动播放
            player.MediaEnded += player_MediaEnded;
            player.MediaFailed += player_MediaFailed;
            // 设置源后自动播放
            player.SetStreamSource(stream);
        }

        void player_MediaFailed ( MediaPlayer sender, MediaPlayerFailedEventArgs args )
        {
            BackgroundMediaPlayer.Shutdown();
            deferral.Complete();
        }

        void player_MediaEnded ( MediaPlayer sender, object args )
        {
            BackgroundMediaPlayer.Shutdown();
            deferral.Complete();
        }

    }

            foreach (IBackgroundTaskRegistration task in BackgroundTaskRegistration.AllTasks.Values)
            {
                if (task.Name == TASKNAME)
                {
                    task.Unregister(true);
                    break;
                }
            }
            // 必须调用以下代码，否则不能注册后台任务
            var result = await BackgroundExecutionManager.RequestAccessAsync();
            if (result == BackgroundAccessStatus.AllowedMayUseActiveRealTimeConnectivity)
            {
                BackgroundTaskBuilder taskbd = new BackgroundTaskBuilder();
                taskbd.Name = TASKNAME;
                taskbd.TaskEntryPoint = ENTRY_POINT; //入口点
                // 添加触发器
                SystemTrigger trigger = new SystemTrigger(SystemTriggerType.UserPresent, false);
                /*
                 * 当用户点亮手机屏幕时就会触发
                 */
                taskbd.SetTrigger(trigger);
                // 注册后台任务
                try
                {
                    var reg = taskbd.Register();
                    tb.Text = "后台任务注册成功。\n" + string.Format("任务名：{0}\n", reg.Name) + string.Format("任务ID：{0}", reg.TaskId);
                }
                catch
                {
                    tb.Text = "后台任务注册失败。";
                }
            }