Notification.Builder builder = new Notification.Builder(context) 
      .setAutoCancel(true) //设置点击通知后自动取消通知
      .setContentTitle("title") //通知标题
      .setContentText("describe") //通知第二行的内容
      .setContentIntent(pendingIntent) //点击通知后，发送指定的PendingIntent
      .setSmallIcon(R.drawable.ic_launcher); //通知图标，必须设置否则通知不显示

            Notification notification = new Notification.Builder(context)
            .setAutoCancel(true)
            .setContentTitle("title")
            .setContentText("text")
            .setSmallIcon(R.mipmap.ic_launcher)
            .setContentIntent(pendingIntent)
            .build();