Notifaction是Android系统的的消息栏，

NotificationManager，然后实例化Notification，设置它的属性，通过NotificationManager 

发出通知就可以了。基本步骤如下：

A.NotificationManarger

1.获取NotificationManarger

String service = Context.NOTIFICATION_SERVICE;

NotificationManager mNotificationManager =（NotificationManager）getSystemService（service）;

2.

Android O以下的话直接通过NotificationManarger.notify(int id, Notification notification)构建系统消息

Android O及以上版本还要构建消息渠道

NotificationChannel mChannel =new NotificationChannel(id, name, NotificationManager.IMPORTANCE_LOW);

  nm.createNotificationChannel(mChannel);

B.Notifaction的创建

1.Android O的创建

Notification notification  =new Notification.Builder(context)

.setChannelId(id)

.setContentTitle("krcm110 new messages")

.setContentText("Success")

.setSmallIcon(R.mipmap.ic_launcher)

.setWhen(System.currentTimeMillis())

.build();

2.Android O以下的版本创建

Notification notification  =new Notification.Builder(context)

NotificationCompat.Builder notificationBuilder =new NotificationCompat.Builder(context)

.setChannelId(id)

.setContentTitle("krcm110 new messages")

.setContentText("Success")

.setSmallIcon(R.mipmap.ic_launcher)

.setOngoing(true)

.setShowWhen(true);

notification = notificationBuilder.build();

//....................................Code..............................................

import android.app.Notification;

import android.app.NotificationChannel;

import android.app.NotificationManager;

import android.app.PendingIntent;

import android.app.RemoteInput;

import android.content.Context;

import android.content.Intent;

import android.graphics.BitmapFactory;

import android.graphics.drawable.Icon;

import android.os.Build;

import android.support.v4.app.NotificationCompat;

import android.widget.RemoteViews;

import android.widget.Toast;

import com.example.krcm110.myapplication.R;

import com.example.krcm110.myapplication.app.view.activity.ActitityB;

import com.example.krcm110.myapplication.app.view.activity.MainActivity;

import com.example.krcm110.myapplication.com.service.ServiceBase;

import com.example.krcm110.myapplication.com.tools.LogUtil;

import java.util.ArrayList;

/**

*

* @author peter

* @date 2018/7/4

*/

public class Notificaitons {

public final static int NOTIFICATION_SAMPLE =0;

public final static StringACTION_SIMPLE ="com.android.peter.notificationdemo.ACTION_SIMPLE";

public final static StringACTION_ACTION ="com.android.peter.notificationdemo.ACTION_ACTION";

public final static StringACTION_YES ="com.android.peter.notificationdemo.ACTION_YES";

public final static StringACTION_NO ="com.android.peter.notificationdemo.ACTION_NO";

public final static StringACTION_DELETE ="com.android.peter.notificationdemo.ACTION_DELETE";

private static volatile NotificaitonssInstance =null;

private Notificaitons() {

}

public static Notificaitons getInstance() {

if(sInstance ==null) {

synchronized (Notificaitons.class) {

if(sInstance ==null) {

sInstance =new Notificaitons();

}

}

}

return sInstance;

}

//  private NotificationManager notificationManager;

    public void sendSimpleNotification(Context context,NotificationManager nm)

{

Intent intent =new Intent(context,ActitityB.class);

intent.setAction(ACTION_SIMPLE);

Intent intent1 =new Intent(context, MainActivity.class);

intent.setAction(ACTION_ACTION);

Intent[] aa =new Intent[2];

aa[0] = intent;

aa[1] = intent1;

PendingIntent pi = PendingIntent.getActivities(context,0,aa,0);

String id ="my_channel_01";

String name="我是渠道名字";

//notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

        Notification notification =null;

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {

NotificationChannel mChannel =new NotificationChannel(id, name, NotificationManager.IMPORTANCE_LOW);

//  Toast.makeText(context, mChannel.toString(), Toast.LENGTH_SHORT).show();

            nm.createNotificationChannel(mChannel);

notification =new Notification.Builder(context)

.setChannelId(id)

.setContentTitle("5 new messages")

.setContentText("hahaha")

.setSmallIcon(R.mipmap.ic_launcher)

.setWhen(System.currentTimeMillis())

.setContentIntent(pi)

.setOngoing(true)

.setDeleteIntent(pi)

.build();

}else

            {

notification =new NotificationCompat.Builder(context)

//设置渠道ID

                    .setChannelId(id)

.setContentTitle("5 new messages")

.setContentText("hahaha")

//设置小图标

                    .setSmallIcon(R.mipmap.ic_launcher)

//点击后自动消失

                        .setAutoCancel(true)

//屏蔽滑动关闭

//.setOngoing(true)

//设置点击通知时的响应事件

                        .setContentIntent(pi)

//设置删除通知时的响应事件

                        .setDeleteIntent(pi)

//显示时间

                    .setShowWhen(true)

.build();

//notification = notificationBuilder.build();

        }

nm.notify(111123, notification);

}

//清除所有的通知

    public void clearAllNotification(NotificationManager nm)

{

nm.cancelAll();

}

}