Xamarin.forms 每天在Xamarin窗体上运行一次的任务

几个月前我开始使用xamarin，直到现在，我还没有必要做这样的事情。 我正在开发一个应用程序，每天运行一次WCF web服务，并验证信息是否真实。如果为真，则应在设备上显示通知。 我的问题是我不知道如何执行它，我读过背景知识和计划任务，但我不太明白如何执行它。我如何使用Xamarin.Forms实现它

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谢谢大家!

对于Android，解决方案需要4个组件：

AlarmManager

设置每日检查计划

BroadCastReceiver

接收每日触发器并调用IntentService

IntentService

执行等待调用

OnBootReceiver

以确保在设备重新启动后再次设置报警

对于iOS，您很可能需要远程推送通知

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以下是Android组件的一些示例代码：

AlarmManager-设置报警

[assembly: Dependency(typeof(AlarmHelper))] // above the namespace
...
class AlarmHelper: IAlarm
{
    var now = Calendar.Instance;
    var alarmTime = Calendar.Instance;
    alarmTime.Set(CalendarField.HourOfDay, settings.AlarmHour); // Set Alarm start Hour
    alarmTime.Set(CalendarField.Minute, settings.AlarmMinutes); // Set Alarm Start Minutes

    if (alarmTime.Before(now))
    {
        alarmTime.Add(CalendarField.Hour, 24);
    }

    var intent = new Intent(Android.App.Application.Context, typeof(ScheduledAlarmHandler));
    var pendingIntent = PendingIntent.GetBroadcast(Android.App.Application.Context, 0, intent, PendingIntentFlags.CancelCurrent);
    var alarmManager = Android.App.Application.Context.GetSystemService(Context.AlarmService) as AlarmManager;

    alarmManager.SetRepeating(AlarmType.RtcWakeup, alarmTime.TimeInMillis, AlarmManager.IntervalDay, pendingIntent); 
}

[BroadcastReceiver]
class ScheduledAlarmHandler : WakefulBroadcastReceiver
{
    public override void OnReceive(Context context, Intent intent)
    {
        Console.WriteLine("ScheduledAlarmHandler", "Starting service @" + SystemClock.ElapsedRealtime());
        Intent service = new Intent(context, typeof(WakefulAPIService)); 
        StartWakefulService(context, service);
    }
}

广播接收器-接收警报

[assembly: Dependency(typeof(AlarmHelper))] // above the namespace
...
class AlarmHelper: IAlarm
{
    var now = Calendar.Instance;
    var alarmTime = Calendar.Instance;
    alarmTime.Set(CalendarField.HourOfDay, settings.AlarmHour); // Set Alarm start Hour
    alarmTime.Set(CalendarField.Minute, settings.AlarmMinutes); // Set Alarm Start Minutes

    if (alarmTime.Before(now))
    {
        alarmTime.Add(CalendarField.Hour, 24);
    }

    var intent = new Intent(Android.App.Application.Context, typeof(ScheduledAlarmHandler));
    var pendingIntent = PendingIntent.GetBroadcast(Android.App.Application.Context, 0, intent, PendingIntentFlags.CancelCurrent);
    var alarmManager = Android.App.Application.Context.GetSystemService(Context.AlarmService) as AlarmManager;

    alarmManager.SetRepeating(AlarmType.RtcWakeup, alarmTime.TimeInMillis, AlarmManager.IntervalDay, pendingIntent); 
}

[BroadcastReceiver]
class ScheduledAlarmHandler : WakefulBroadcastReceiver
{
    public override void OnReceive(Context context, Intent intent)
    {
        Console.WriteLine("ScheduledAlarmHandler", "Starting service @" + SystemClock.ElapsedRealtime());
        Intent service = new Intent(context, typeof(WakefulAPIService)); 
        StartWakefulService(context, service);
    }
}

IntentService-执行等待的呼叫

[Service]
[IntentFilter(new String[] { "com.test.testApp.WakefulAPIService" })]
class WakefulAPIService : IntentService
{
    protected override void OnHandleIntent(Intent intent)
    {
        // Your API Call code here

        Console.WriteLine("WakefulAPIService", "Completed service @ " + SystemClock.ElapsedRealtime());
        Android.Support.V4.Content.WakefulBroadcastReceiver.CompleteWakefulIntent(intent);
    }
}

OnBootReceiver-确保在设备重新启动后再次设置报警

[BroadcastReceiver(Enabled = true)]
[IntentFilter(new[] { "android.intent.action.BOOT_COMPLETED", "android.intent.action.QUICKBOOT_POWERON" })]
class OnBootReceiver : BroadcastReceiver
{

    public override void OnReceive(Context context, Intent intent)
    {
        Console.WriteLine("On Boot Reveiver", "Alarm Set Again after Reboot");
        var alarmHelper = new AlarmHelper();
        alarmHelper.SetAlarm();
    }

}

此操作所需的权限是“接收启动完成”和“唤醒锁定”

在本例中，对于您可以使用的Android，请参阅此类

[Service(Name = "com.xamarin.samples.downloadscheduler.DownloadJob", 
         Permission = "android.permission.BIND_JOB_SERVICE")]
public class DownloadJob : JobService
{
    public override bool OnStartJob(JobParameters jobParams)
    {            
        Task.Run(() =>
        {
            //Your periodic task here
        });

        return true;  
    }

    public override bool OnStopJob(JobParameters jobParams)
    {
        //true so we re-schedule the task
        return true; 
    }
}

然后您可以创建一个工厂来调用此服务

public static class ReadLocationSchedulerFactory
    {
        public static JobInfo.Builder CreateJobBuilderUsingJobId<T>(this Context context, int jobId) where T : JobService
        {
            var javaClass = Java.Lang.Class.FromType(typeof(T));
            var componentName = new ComponentName(context, javaClass);
            return new JobInfo.Builder(jobId, componentName);
        }

    }

公共静态类ReadLocationSchedulerFactory
{
public static JobInfo.Builder CreateJobBuilderSingJobId（此上下文，int jobId），其中T:JobService
{
var javaClass=Java.Lang.Class.FromType（typeof（T））；
var componentName=新的componentName（上下文，javaClass）；
返回新的JobInfo.Builder（jobId，componentName）；
}
}

然后在你的主要活动中，你必须给工厂打电话

protected override void OnCreate(Bundle bundle)
        {                                
            base.OnCreate(bundle);

            global::Xamarin.Forms.Forms.Init(this, bundle);
            LoadApplication(new App172S.App());

            #region Scheduler

            var jobBuilder = this.CreateJobBuilderUsingJobId<ReadLocationScheduler>(152);
            //This means each 20 mins                
            jobBuilder.SetPeriodic(20 * 60 * 1000); 
            //Persists over phone restarts
            jobBuilder.SetPersisted(true); 
            //If Fails re-try each 2 mins
            jobBuilder.SetBackoffCriteria(120 * 1000, BackoffPolicy.Linear); 
            var jobInfo = jobBuilder.Build();

            var jobScheduler = (JobScheduler)GetSystemService(JobSchedulerService);
            jobScheduler.Cancel(152);
            var scheduleResult = jobScheduler.Schedule(jobInfo);

            if (JobScheduler.ResultSuccess == scheduleResult)
            {
                //If OK maybe show a msg
            }
            else
            {
               //If Failed do something
            }

            #endregion

        }

protectedoverride void OnCreate（捆绑包）
{                                
base.OnCreate（bundle）；
全局：：Xamarin.Forms.Forms.Init（这个，bundle）；
LoadApplication（新的App172S.App（））；
#区域调度器
var jobBuilder=this.CreateJobBuilderUsingJobId（152）；
//这意味着每20分钟
jobBuilder.SetPeriodic（20*60*1000）；
//通过电话重新启动
jobBuilder.SetPersisted（true）；
//如果失败，请每2分钟重试一次
jobBuilder.Setbackoff标准（120*1000，BackoffPolicy.Linear）；
var jobInfo=jobBuilder.Build（）；
var jobScheduler=（jobScheduler）GetSystemService（JobSchedulerService）；
jobScheduler.Cancel（152）；
var scheduleResult=jobScheduler.Schedule（jobInfo）；
if（JobScheduler.ResultSuccess==schedulesult）
{
//如果确定，可能会显示一个消息
}
其他的
{
//如果失败了，做点什么
}
#端区
}

google“ios/android计划任务”、“dependencyservice”不是每次创建

MainActivity

时都会更新作业吗？换句话说，如果我想让作业在12:00，12:20运行。。。我在12:10打开应用程序，作业配置更改为12:10、12:30运行。。。？