Notification 的创建主要涉及到 Notification.Builder 、 Notification 、 NotificationManager 。

Notification.Builer : 使用建造者模式构建 Notification 对象。由于 Notification.Builder 仅支持 Android 4.1及之后的版本，为了解决兼容性问题， Google 在 Android Support v4 中加入了 NotificationCompat.Builder 类。对于某些在 Android 4.1 之后才特性，即使 NotificationCompat.Builder 支持该方法，在之前的版本中也不能运行。点我查看更多关于 Notification 兼容性问题处理。文中使用的都是 NotificationCompat。
Notification : 通知对应类，保存通知相关的数据。NotificationManager 向系统发送通知时会用到。
NotificationManager : NotificationManager 是通知管理类，它是一个系统服务。调用 NotificationManager 的 notify() 方法可以向系统发送通知。

1.获取 NotificationManager 对象：

notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

2.Builder

a.普通通知

 Notification.Builder builder = new Notification.Builder(this);
        Intent mIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://blog.csdn.net/itachi85/"));
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, mIntent, 0);
        builder.setContentIntent(pendingIntent);
        builder.setSmallIcon(R.drawable.lanucher);
        builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.lanucher));
        builder.setAutoCancel(true);
        builder.setContentTitle("普通通知");
        selectNotofovatiomLevel(builder);
        notificationManager.notify(0, builder.build());

b.折叠式通知

Notification.Builder builder = new Notification.Builder(this);
        Intent mIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://blog.csdn.net/itachi85/"));
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, mIntent, 0);
        builder.setContentIntent(pendingIntent);
        builder.setSmallIcon(R.drawable.foldleft);
        builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.lanucher));
        builder.setAutoCancel(true);
        builder.setContentTitle("折叠式通知");
        selectNotofovatiomLevel(builder);
        //用RemoteViews来创建自定义Notification视图
        RemoteViews remoteViews = new RemoteViews(getPackageName(), R.layout.view_fold);
        Notification notification = builder.build();
        //指定展开时的视图
        notification.bigContentView = remoteViews;
        notificationManager.notify(1, notification);

c.悬挂式通知

Notification.Builder builder = new Notification.Builder(this);
        Intent mIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://blog.csdn.net/itachi85/"));
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, mIntent, 0);
        builder.setContentIntent(pendingIntent);
        builder.setSmallIcon(R.drawable.foldleft);
        builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.lanucher));
        builder.setAutoCancel(true);
        builder.setContentTitle("悬挂式通知");
        selectNotofovatiomLevel(builder);
        //设置点击跳转
        Intent hangIntent = new Intent();
        hangIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        hangIntent.setClass(this, MyNotificationActivity.class);
        //如果描述的PendingIntent已经存在，则在产生新的Intent之前会先取消掉当前的
        PendingIntent hangPendingIntent = PendingIntent.getActivity(this, 0, hangIntent, PendingIntent.FLAG_CANCEL_CURRENT);
        builder.setFullScreenIntent(hangPendingIntent, true);

        notificationManager.notify(2, builder.build());