如何创建通知

随着Android系统不断升级，Notification的创建方式也随之变化，主要变化如下:

Android 3.0之前

Android 3.0 (API level 11)之前，使用new Notification()方式创建通知:

NotificationManager mNotifyMgr = 
      (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
PendingIntent contentIntent = PendingIntent.getActivity(
      this, 0, new Intent(this, ResultActivity.class), 0);

Notification notification = new Notification(icon, tickerText, when);
notification.setLatestEventInfo(this, title, content, contentIntent);

mNotifyMgr.notify(NOTIFICATIONS_ID, notification);

Android 3.0 (API level 11)及更高版本

Android 3.0开始弃用new Notification()方式，改用Notification.Builder()来创建通知:

NotificationManager mNotifyMgr = 
      (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
PendingIntent contentIntent = PendingIntent.getActivity(
      this, 0, new Intent(this, ResultActivity.class), 0);

Notification notification = new Notification.Builder(this)
            .setSmallIcon(R.drawable.notification_icon)
            .setContentTitle("My notification")
            .setContentText("Hello World!")
            .setContentIntent(contentIntent)
            .build();// getNotification()

mNotifyMgr.notify(NOTIFICATIONS_ID, notification);

这里需要注意: "build()" 是Androdi 4.1(API level 16)加入的，用以替代
"getNotification()"。API level 16开始弃用"getNotification()"

通知基本用法

一个通知必须包含以下三项属性:
小图标，对应 setSmallIcon()
通知标题，对应 setContentTitle()
详细信息，对应 setContentText()
其他属性均为可选项，更多属性方法请参考https://blog.csdn.net/yxncl/article/details/72801230。
创建通知
1、实例化一个NotificationCompat.Builder对象

NotificationCompat.Builder mBuilder = 
      new NotificationCompat.Builder(this)
            .setSmallIcon(R.drawable.notification_icon)
            .setContentTitle("My notification")
            .setContentText("Hello World!");

NotificationCompat.Builder自动设置的默认值:
priority: PRIORITY_DEFAULT
when: System.currentTimeMillis()
audio stream: STREAM_DEFAULT

定义并设置一个通知动作(Action)

Intent resultIntent = new Intent(this, ResultActivity.class);
PendingIntent resultPendingIntent = PendingIntent.getActivity(
            this, 0, resultIntent, PendingIntent.FLAG_UPDATE_CURRENT);
mBuilder.setContentIntent(resultPendingIntent);

生成Notification对象

Notificatioin notification = mBuilder.build();

使用NotificationManager发送通知

// Sets an ID for the notification
int mNotificationId = 001;

// Gets an instance of the NotificationManager service
NotificationManager mNotifyMgr = 
      (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

// Builds the notification and issues it.
mNotifyMgr.notify(mNotificationId, notification);

更新通知
更新通知很简单，只需再次发送相同ID的通知即可，如果之前的通知依然存在则会更新通知属性，如果之前通知不存在则重新创建。示例代码:

NotificationManager mNotifyMgr = 
      (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
// Sets an ID for the notification, so it can be updated
int notifyID = 1;
NotificationCompat.Builder mNotifyBuilder = 
      new NotificationCompat.Builder(this)
          .setContentTitle("New Message")
          .setContentText("You've received new messages.")
          .setSmallIcon(R.drawable.ic_notify_status);

int numMessages = 0;
...
    mNotifyBuilder.setContentText("new content text")
            .setNumber(++numMessages);
    mNotifyMgr.notify(notifyID, mNotifyBuilder.build());
...

取消通知
取消通知有如下4种方式:

点击通知栏的清除按钮，会清除所有可清除的通知
设置了 setAutoCancel() 或 FLAG_AUTO_CANCEL的通知，点击该通知时会清除它
通过 NotificationManager 调用 cancel() 方法清除指定ID的通知
通过 NotificationManager 调用 cancelAll() 方法清除所有该应用之前发送的通知