通知的布局

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创建通知通道

在 Android 8.0 上运行的应用必须为其通知创建通知通道。通知通道需要以下三条信息：

标识通道的包唯一的 ID 字符串。
将显示给用户的通道的名称。名称必须介于 1 到 40 个字符之间。
通道的重要性。
应用需要检查其正在运行的 Android 版本。运行版本低于 Android 8.0 的设备不应创建通知通道。以下方法是如何在活动中创建通知通道的一个示例：

void CreateNotificationChannel()
{
    if (Build.VERSION.SdkInt < BuildVersionCodes.O)
    {
        // Notification channels are new in API 26 (and not a part of the
        // support library). There is no need to create a notification
        // channel on older versions of Android.
        return;
    }

    var channelName = Resources.GetString(Resource.String.channel_name);
    var channelDescription = GetString(Resource.String.channel_description);
    var channel = new NotificationChannel(CHANNEL_ID, channelName, NotificationImportance.Default)
                  {
                      Description = channelDescription
                  };

    var notificationManager = (NotificationManager) GetSystemService(NotificationService);
    notificationManager.CreateNotificationChannel(channel);
}

创建和发布通知

若要在 Android 中生成通知，请执行以下步骤：

实例化 NotificationCompat.Builder 对象。
对对象调用各种方法 NotificationCompat.Builder 以设置通知选项。
调用对象的 Build 方法 NotificationCompat.Builder 以实例化通知对象。
List item

调用通知管理器的 Notify 方法发布通知。

必须至少为每个通知提供以下信息：

大小 (为 24x24 dp 的小型图标)
简短标题
通知的文本

下面的代码示例演示如何用于 NotificationCompat.Builder 生成基本通知。请注意， NotificationCompat.Builder 方法支持方法链接;也就是说，每个方法返回生成器对象，以便可以使用最后一个方法调用的结果调用下一个方法调用：

// Instantiate the builder and set notification elements:
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, CHANNEL_ID)
    .SetContentTitle ("Sample Notification")
    .SetContentText ("Hello World! This is my first notification!")
    .SetSmallIcon (Resource.Drawable.ic_notification);

// Build the notification:
Notification notification = builder.Build();

// Get the notification manager:
NotificationManager notificationManager =
    GetSystemService (Context.NotificationService) as NotificationManager;

// Publish the notification:
const int notificationId = 0;
notificationManager.Notify (notificationId, notification);

我的样例

效果图

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代码

using Android.App;
using Android.Content;
using Android.Graphics;
using Android.Media;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using AndroidX.AppCompat.App;
using AndroidX.Core.App;
//using Android.Support.V4.App;
//using TaskStackBuilder = Android.Support.V4.App.TaskStackBuilder;
//using Android.Media;

namespace 我的第一个安卓程序
{
    [Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
    public class MainActivity : AppCompatActivity
    {
        static readonly int NOTIFICATION_ID = 1000;
        static readonly string CHANNEL_ID = "notice"; 
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.activity_main);

            #region 创建通知通道


            if (Build.VERSION.SdkInt < BuildVersionCodes.O)
            {
                // Notification channels are new in API 26 (and not a part of the
                // support library). There is no need to create a notification
                // channel on older versions of Android.
                return;
            }

            var name = Resources.GetString(Resource.String.channel_name);
            var description = GetString(Resource.String.channel_description);
            var channel = new NotificationChannel(CHANNEL_ID, name, NotificationImportance.High)
            {
                Description = description,
                
            };

            var notificationManager = (NotificationManager)GetSystemService(NotificationService);
            notificationManager.CreateNotificationChannel(channel);


            #endregion


            #region *****************在这里添加了用户控件处理代码start*****************
            //找到两个edittext
            var txtInput = FindViewById<EditText>(Resource.Id.txtInput);
            var txtNumInput = FindViewById<EditText>(Resource.Id.txtNumInput);
            //找到btn按钮
            var button = FindViewById<Button>(Resource.Id.btnTest);
            button.Click += (es, ee) =>
            {
                //吐司内容
                Toast.MakeText(this, $"txtInput的内容是：{txtInput.Text}，txtNumInput数字是：{txtNumInput.Text}", ToastLength.Long).Show();
            };
            #endregion *****************在这里添加了用户控件处理代码end*****************
        }
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }

        [Java.Interop.Export]
        public void ShowMessage(View viwe)
        {
            Toast.MakeText(this, $" 这是通过ShowMessage进来的", ToastLength.Long).Show();
        }


        [Java.Interop.Export]
        public void ShowSecondActivity(View viwe)
        {
            StartActivity(typeof(SecondActivity));
        }

        [Java.Interop.Export]
        public void ShowIntetActivity(View viwe)
        {
            Intent intent = new Intent();
            intent.SetClass(this, typeof(SecondActivity));
            StartActivity(intent);
        }


        int count = 0;
        [Java.Interop.Export]
        public void ShowSystemNotice(View view)
        {
            // Instantiate the Image (Big Picture) style:
            NotificationCompat.BigPictureStyle  picStyle = new NotificationCompat.BigPictureStyle(); 
          // Convert the image to a bitmap before passing it into the style:
          picStyle.BigPicture(BitmapFactory.DecodeResource(Resources, Resource.Drawable.notice));

            // Set the summary text that will appear with the image:
            picStyle.SetSummaryText("就是超级大的图标能咋滴？");


            // "notice" 是通知通道，这个可以自己定义
            NotificationCompat.Builder builder = new NotificationCompat.Builder(this, CHANNEL_ID)
                .SetContentTitle("这是一个通知")
                .SetContentText("我现在通知你啦， Hello World!")
                .SetDefaults((int)NotificationDefaults.All)
                .SetSound(RingtoneManager.GetDefaultUri(RingtoneType.Ringtone)) 
                .SetSmallIcon(Resource.Mipmap.notice_small)
                .SetLargeIcon(BitmapFactory.DecodeResource(Resources, Resource.Drawable.notice_normal))
                .SetStyle(picStyle);

            // Build the notification:
            Notification notification = builder.Build();

            // Get the notification manager:
            var notificationManager = NotificationManagerCompat.From(this); 
           
            notificationManager.Notify(NOTIFICATION_ID, notification);
        }
    }
}