專案網址https://github.com/uuko/android_project/tree/master/Notifaction
參考文章 android官方document+codelab
每個通知通道代表一種通知類型。
在您的代碼中，您可以在每個通知通道中將多個通知分組。
對於每個通知通道，您的應用程序設置行為的通道，並且行為被應用到該頻道的所有通知。例如，您的應用可能會在頻道中設置通知以播放聲音，閃爍燈光或振動。
無論您的應用為通知渠道設置了什麼行為，用戶都可以更改該行為，並且用戶可以完全關閉您的應用的通知。

//每個channel與唯一id相連 
 private static final String PRIMARY_CHANNEL_ID ="primary_notification_channel";
  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button notify=(Button) findViewById(R.id.notify);
        notify.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                sendNotification();
            }
        });
       ** createNotificationChannel();**

    }
   public void sendNotification(){
                                                  //builder實例
        NotificationCompat.Builder notifyBuilder = getNotificationBuilder();
        notificationManager.**notify**(NOTIFICATION_ID, notifyBuilder.build());
    }  
//notificationmanger >傳遞給用戶的
 private NotificationManager notificationManager;

public void createNotificationChannel() 
{//實體化manager並設置一些參數
     notificationManager=
            (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
        if (Build.VERSION.SDK_INT>=android.os.Build.VERSION_CODES.O){
        /*創建一個channel對象 public NotificationChannel (String id, 
                CharSequence name, 
                int importance)*/
            NotificationChannel notificationChannel=
                    new NotificationChannel(PRIMARY_CHANNEL_ID,
                            "123" ,NotificationManager.IMPORTANCE_HIGH
                            );
            notificationChannel.enableLights(true);
            notificationChannel.setLightColor(Color.RED);
            notificationChannel.enableVibration(true);
            notificationChannel.setDescription("hihi");
 //正式創建                   notificationManager.createNotificationChannel(notificationChannel);
           }
}
//使用NotificationCompat.Builder該類創建通知
//需要一個ID讓通知相關 以好取消OR更新
private static final int NOTIFICATION_ID = 0;
private NotificationCompat.Builder getNotificationBuilder(){

        Intent notifyIntent=new Intent(this,MainActivity.class);
        //intent必須包在pendingintent裡面
        PendingIntent notifyPendingIntent=PendingIntent.getActivity(this,
                NOTIFICATION_ID,notifyIntent,PendingIntent.FLAG_UPDATE_CURRENT);
                //FLAG_UPDATE_CURRENT>第二條會替換第一條內容 CANCEL是會變點第一條沒反應只有第二條可以點
        NotificationCompat.Builder notifyBuilder=
                new NotificationCompat.Builder(this,PRIMARY_CHANNEL_ID)
                        .setContentTitle("notify~~~")
                        .setContentText("uuko notify!!")
                        .setSmallIcon(R.drawable.ic_launcher_background)
                        .setContentIntent(notifyPendingIntent)//加入intent
                        .setAutoCancel(true);
        return notifyBuilder;
    }

觀念>
通知為您的應用提供了一種與用戶進行交互的方式，即使該應用未運行也是如此。
當Android發布通知時，該通知首先顯示為設備通知區域中的圖標。
(這可以用intent+pendingintent去做 再加broadcast)
要指定通知的UI和操作，請使用NotificationCompat.Builder。
要創建通知，請使用NotificationCompat.Builder.build()。
要發出通知，請使用NotificationManager.notify()將該通知對像傳遞給Android運行時系統。
為了使更新或取消通知成為可能，請將通知ID與通知相關聯。
通知可以包含多個組件，包括一個小圖標（setSmallIcon()，必填）；標題（setContentTitle()）; 以及詳細的文字（setContentText()）。
通知還可以包括待處理的意圖，擴展的樣式，優先級等。有關更多詳細信息，請參見 NotificationCompat.Builder。

//功能拓展

public class MainActivity extends AppCompatActivity {
    private static final String PRIMARY_CHANNEL_ID = "primary_notification_channel";
    private NotificationManager notificationManager;
    private static final int NOTIFICATION_ID = 0;
    private static final String ACTION_UPDATE_NOTIFICATION =
            "com.example.android.Notifaction.ACTION_UPDATE_NOTIFICATION";
    private NotificationReciever notificationReciever;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        notificationReciever=new NotificationReciever();
        Button update=(Button) findViewById(R.id.update);
        update.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                updateNotification();
            }
        });
        Button cancel=(Button) findViewById(R.id.cancel);
        cancel.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                cancelupdateNotification();
            }
        });
        Button notify=(Button) findViewById(R.id.notify);
        notify.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                sendNotification();
            }
        });
        createNotificationChannel();
        setbuttonstate(true,false,false);
        registerReceiver(notificationReciever,new IntentFilter(ACTION_UPDATE_NOTIFICATION));
    }
    
    @Override
    public void onDestroy(){
        unregisterReceiver(notificationReciever);
        super.onDestroy();
    }
    //更新
    public  void updateNotification(){
        Bitmap bitmap= BitmapFactory.decodeResource(getResources(),R.drawable.mascot_1);
        NotificationCompat.Builder notifybuilder=getNotificationBuilder();
        notifybuilder.setStyle(new NotificationCompat.BigPictureStyle()
                .bigPicture(bitmap)
                .setBigContentTitle("bigggg"));
        notificationManager.notify(NOTIFICATION_ID,notifybuilder.build());
        setbuttonstate(false,true,true);
    }
    //取消通知
    public  void  cancelupdateNotification(){
        notificationManager.cancel(NOTIFICATION_ID);
    }
    public void sendNotification(){
        Intent intent=new Intent(ACTION_UPDATE_NOTIFICATION);
        PendingIntent pendingIntent=PendingIntent.getBroadcast(this,NOTIFICATION_ID,intent,PendingIntent.FLAG_UPDATE_CURRENT);
        NotificationCompat.Builder notifyBuilder = getNotificationBuilder();
        notifyBuilder.addAction(R.drawable.ic_update,"update",pendingIntent);
        notificationManager.notify(NOTIFICATION_ID, notifyBuilder.build());
        setbuttonstate(false,true,true);
    }
    void setbuttonstate(Boolean isNotifyEnabled,Boolean isUpdadateEnabled,Boolean isCancelEnabled){
        Button update=(Button) findViewById(R.id.update);
        Button notify=(Button) findViewById(R.id.notify);
        Button cancel=(Button) findViewById(R.id.cancel);
        notify.setEnabled(isNotifyEnabled);
        update.setEnabled(isUpdadateEnabled);
        cancel.setEnabled(isCancelEnabled);
    }
    public void   createNotificationChannel(){
        notificationManager=
            (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
        if (Build.VERSION.SDK_INT>=android.os.Build.VERSION_CODES.O){
            NotificationChannel notificationChannel=
                    new NotificationChannel(PRIMARY_CHANNEL_ID,
                            "123" ,NotificationManager.IMPORTANCE_HIGH
                            );
            notificationChannel.enableLights(true);
            notificationChannel.setLightColor(Color.RED);
            notificationChannel.enableVibration(true);
            notificationChannel.setDescription("hihi");
            notificationManager.createNotificationChannel(notificationChannel);
        }
    }

    private NotificationCompat.Builder getNotificationBuilder(){

        Intent notifyIntent=new Intent(this,MainActivity.class);
        PendingIntent notifyPendingIntent=PendingIntent.getActivity(this,
                NOTIFICATION_ID,notifyIntent,PendingIntent.FLAG_UPDATE_CURRENT);
        NotificationCompat.Builder notifyBuilder=
                new NotificationCompat.Builder(this,PRIMARY_CHANNEL_ID)
                        .setContentTitle("notify~~~")
                        .setContentText("uuko notify!!")
                        .setSmallIcon(R.drawable.ic_launcher_background)
                        .setContentIntent(notifyPendingIntent)
                        .setAutoCancel(true);
        return notifyBuilder;
    }

    public class  NotificationReciever extends BroadcastReceiver{
        public NotificationReciever(){

        }

        @Override
        public void onReceive(Context context, Intent intent) {
            updateNotification();
        }

    }


}