C# Handler.Post方法代码示例

 protected void RunOnMainThread(Action action)
 {
     Handler handler = new Handler(Looper.MainLooper);
     handler.Post(action);
     handler.Dispose();
     handler = null;
 }

        public void BeginGeofencing(object sender, EventArgs eventArgs)
        {
            if (!apiClient.IsConnected) {
                var myHandler = new Handler ();
                myHandler.Post (() => {
                    Android.Widget.Toast.MakeText (this, "Google API Not Connected. Try Again.", Android.Widget.ToastLength.Long).Show ();
                });
                return;
            }

            try {
                if (connectedGeofences.Count >= 1) {
                    LocationServices.GeofencingApi.AddGeofences(apiClient, getGeofencingRequest(), getGeofencePendingIntent()).SetResultCallback(this);
                    string geofenceAnnounce = "Geofences Active At The Following Locations:\n";
                    foreach (ROMPGeofence geofName in connectedGeofences) {
                        geofenceAnnounce += geofName.Id + "\n";
                    }
                    var myHandler = new Handler ();
                    myHandler.Post (() => {
                        Android.Widget.Toast.MakeText (this, geofenceAnnounce, Android.Widget.ToastLength.Long).Show ();
                    });
                    FindViewById<Button>(Resource.Id.btnBegin).Visibility = ViewStates.Invisible;
                    FindViewById<TextView>(Resource.Id.lblConfirm).SetText("A record that you have checked-in will be made in the log of your education activity for this ROMP rotation when this device enters a 1km radius surrounding the facility of your ROMP rotation.", TextView.BufferType.Normal);
                    geofenceRequestIntent = PendingIntent.GetService (this, 0,
                        new Intent (this, Java.Lang.Class.FromType (typeof(GeofenceTransitionsIntentService))),
                        PendingIntentFlags.UpdateCurrent);
                } else {
                    FindViewById<Button>(Resource.Id.btnBegin).Visibility = ViewStates.Invisible;
                    FindViewById<TextView>(Resource.Id.lblConfirm).SetText("No Rotations Available, Please Try Within Your Scheduled Rotation Dates", TextView.BufferType.Normal);
                }
            } catch (SecurityException securityEx) {
                logSecurityException (securityEx);
            }
        }

		private void CreateNotifications(Context context, string action, bool isMessageNeeded = true, bool isToastNeeded = true)
		{
			#if DEBUG
			try {
				if (isMessageNeeded)
				{
					Notification notification = new Notification.Builder(context)
						.SetContentTitle ("BluetoothNotify intent received " + action)
						.SetContentText ("message sent at" + System.DateTime.Now.ToLongTimeString ())
						.SetSmallIcon (Resource.Drawable.icon)
						.Build ();

					NotificationManager nMgr = (NotificationManager)context.GetSystemService (Android.Content.ContextWrapper.NotificationService);
					nMgr.Notify (0, notification);
				}

				if (isToastNeeded)
				{
					var myHandler = new Handler ();
					myHandler.Post (() =>  {
						Toast.MakeText (context, "BluetoothNotify intent received " + action, ToastLength.Long).Show ();
					});
				}
				
			} catch (Exception ex) {
				Log.Info ("com.tarabel.bluetoothnotify", "CreateNotification error in IntentReceiver " + ex.ToString());
			}
			#endif
		}

		private void Peer_PeerConnected (object sender, PeerConnectedEventArgs args)
		{
			using (var h = new Handler (Looper.MainLooper))
				h.Post (() => {
					textView.Text = args.PeerId;
				});
		}

 public void OnClick(View v)
 {
     Handler h = new Handler();
     h.Post(() => {
         this.Img.StartAnimation(this.AniSet);
     });
 }

		protected override void OnLayout (bool changed, int l, int t, int r, int b)
		{
			using (var h = new Handler (Looper.MainLooper)) {
				h.Post (() => {
					double width = base.Context.FromPixels ((double)(r - l));
					double height = base.Context.FromPixels ((double)(b - t));
					var size = new Size (width, height);

					var msw = MeasureSpec.MakeMeasureSpec (r - l, MeasureSpecMode.Exactly);
					var msh = MeasureSpec.MakeMeasureSpec (b - t, MeasureSpecMode.Exactly);
					_nativeView.Measure (msw, msh);
					_nativeView.Layout (0, 0, r - l, b - t);

					//			if (size != _previousSize) {
					var layout = _viewCell.View as Layout<Xamarin.Forms.View>;
					if (layout != null) {
						layout.Layout (new Rectangle (0, 0, width, height));
						layout.ForceLayout ();
						FixChildLayouts (layout);
						_isLaidOut = true;
					}
					_previousSize = size;
				});
			}
			//			}
		}

		public void Update (object bindingContext)
		{
			using (var h = new Handler (Looper.MainLooper)) {
				h.Post (() => {
					_viewCell.BindingContext = bindingContext;
				});
			}
		}

		private void StartPlayingHandler()
		{
			var handler = new Handler();
			var runnable = new Runnable(() => { handler.Post(OnPlaying); });
			if (!_executorService.IsShutdown)
			{
				_scheduledFuture = _executorService.ScheduleAtFixedRate(runnable, 100, 1000, TimeUnit.Milliseconds);
			}
		}

 public void Invoke(Action action)
 {
     //Another method
     //http://stackoverflow.com/questions/11123621/running-code-in-main-thread-from-another-thread
     var l = Android.OS.Looper.MainLooper; //Previously Context.GetMainLooper()
     Handler mainHandler = new Handler(l);
     Runnable myRunnable = new Runnable(action);
     mainHandler.Post(myRunnable);
 }

        protected override void OnCreate(Bundle bundle)
        {
            RequestWindowFeature(WindowFeatures.NoTitle);
            base.OnCreate (bundle);
            SetContentView (Resource.Layout.ChooseMode);
            try {
                string sessionKey = Intent.GetStringExtra ("SessionKey");
                int groupID = Intent.GetIntExtra ("GroupID", 0);
                int userID = Intent.GetIntExtra ("UserID", 0);
                var locSvc = new ROMPLocation ();
                Button button = FindViewById<Button> (Resource.Id.btnChoose);
                CheckBox cbpassive = FindViewById<CheckBox> (Resource.Id.cbPassive);
                CheckBox cbactive = FindViewById<CheckBox> (Resource.Id.cbActive);

                cbpassive.Click += (o, e) => {
                    if (cbactive.Checked) {
                        cbactive.Checked = false;
                    }
                };

                cbactive.Click += (o, e) => {
                    if (cbpassive.Checked) {
                        cbpassive.Checked = false;
                    }
                };

                button.Click += delegate {
                    if (cbactive.Checked) {
                        var nextActivity = new Intent(this, typeof(CheckInActivity));
                        nextActivity.PutExtra("SessionKey", sessionKey);
                        nextActivity.PutExtra("GroupID", groupID);
                        nextActivity.PutExtra("UserID", userID);
                        StartActivity(nextActivity);
                        Finish();
                    } else if (cbpassive.Checked) {
                        var nextActivity = new Intent(this, typeof(CheckInPassiveActivity));
                        nextActivity.PutExtra("SessionKey", sessionKey);
                        nextActivity.PutExtra("GroupID", groupID);
                        nextActivity.PutExtra("UserID", userID);
                        StartActivity(nextActivity);
                        Finish();
                    } else {
                        string errmsg = "Please choose a check in method before proceeding.";
                        var myHandler = new Handler();
                        myHandler.Post(() => {
                            Toast.MakeText(this, errmsg, ToastLength.Short).Show();
                        });
                    }
                };
            } catch (Exception e) {
                var myHandler = new Handler();
                myHandler.Post(() => {
                    Android.Widget.Toast.MakeText(this, e.Message, Android.Widget.ToastLength.Long).Show();
                });
                System.Diagnostics.Debug.Write (e.Message);
            }
        }

 public override void Send(SendOrPostCallback d, object state)
 {
     var looper = Looper.MainLooper;
     if (Looper.MyLooper() == looper) {
         d (state);
         return;
     }
     var m = new ManualResetEvent (false);
     using (Handler h = new Handler (looper)) {
         h.Post (() => {
             d (state);
             m.Set ();
         });
     }
     m.WaitOne ();
 }

		public GridViewCellContainer (Context context, FastGridCell fastGridCell, global::Android.Views.View parent, Size initialCellSize) : base (context)
		{
			using (var h = new Handler (Looper.MainLooper)) {
				h.Post (() => {
					_parent = parent;
					_viewCell = fastGridCell;
					fastGridCell.PrepareCell (initialCellSize);
//					_viewCell.View.BackgroundColor = Xamarin.Forms.Color.Green;
					var renderer = fastGridCell.View.GetOrCreateRenderer ();
					_nativeView = renderer.ViewGroup;
//					SetBackgroundColor (Android.Graphics.Color.Yellow);
					AddView (_nativeView);
				});
			}

		}

        protected override void OnHandleIntent(Intent intent)
        {
            // Can use intent to pass data to the service.
            var val = intent.GetStringExtra(IntentValueKey);

            // IntentService uses queued worker threads. To do something on the UI we must invoke on the main thread.
            var handler = new Handler(Looper.MainLooper);
            handler.Post(() => {
                Toast.MakeText(this, $"OnHandleIntent({val})", ToastLength.Long).Show();
            });

            for(int i = 1; i < 20; i++)
            {
                MainActivity.L($"Processing...{i}");
                Thread.Sleep(1000);
            }
        }

		void CreateNotifications(string status)
		{
			#if DEBUG
				Notification notification = new Notification.Builder (this)
				.SetContentTitle ("BluetoothLowEnergySearchService " + status)
				.SetContentText ("message sent at" + System.DateTime.Now.ToLongTimeString ())
				.SetSmallIcon (Resource.Drawable.icon)
				.Build ();

			NotificationManager nMgr = (NotificationManager)GetSystemService (NotificationService);
			nMgr.Notify (0, notification);

			var myHandler = new Handler ();
			myHandler.Post (() =>  {
				Toast.MakeText (this, "BluetoothLowEnergySearchService "+ status, ToastLength.Long).Show ();
			});
			#endif
		}

		public List<string> GetDeviceList(Context context)
		{
			
			List<string> result = new List<string> ();

			// Get local Bluetooth adapter
			BluetoothAdapter bluetoothAdapter = BluetoothAdapter.DefaultAdapter;

			// If the adapter is null, then Bluetooth is not supported
			if (bluetoothAdapter == null) {
				var myHandler = new Handler ();
				myHandler.Post (() =>  {
					Toast.MakeText (context, "Bluetooth is not available", ToastLength.Long).Show ();
				});
				return result;
			}

			// If bluetooth is not enabled, ask to enable it
			if (!bluetoothAdapter.IsEnabled)
			{
				var myHandler = new Handler ();
				myHandler.Post (() =>  {
					Toast.MakeText (context, "Bluetooth is not enabled, please enable it", ToastLength.Long).Show ();
				});
				var enableBtIntent = new Intent(BluetoothAdapter.ActionRequestEnable);
			}

			// Get connected devices
			var listOfDevices = bluetoothAdapter.BondedDevices;
			if (listOfDevices.Count > 0)
			{
				foreach (var bluetoothDevice in listOfDevices)
				{
					if (!result.Contains(bluetoothDevice.Name + ":" + bluetoothDevice.Address))
						result.Add(bluetoothDevice.Name + ":" + bluetoothDevice.Address);
				}
			}

			return result;
		}