android 如何比较未决意向

Question

PendingIntent.FLAG_NO_CREATE 的文档如下：

Flag indicating that if the described PendingIntent does not already exist, then simply return null instead of creating it.

我的问题：使用什么标准来比较 PendingIntents？

我猜这个标志在幕后使用 PendingIntent.equals，但我不太确定该函数使用的是什么标准。是否使用了操作、请求代码、类别、附加功能（我猜没有）等？

上下文：

如果我的闹钟尚未设置，我想启动一个带有未决意图的闹钟。具体来说，我正在关注这个 answer.

Intent i = new Intent(applicationContext, MyService.class);
i.setAction("myAction");
PendingIntent pi = PendingIntent.getService(applicationContext, /*requestCode*/0, i, PendingIntent.FLAG_NO_CREATE);
if (pi != null) {
  AlarmManager alarmMgr = (AlarmManager)applicationContext.getSystemService(Context.AlarmService);
  alarmMgr.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, AlarmManager.INTERVAL_HOUR, AlarmManager.INTERVAL_HOUR, pi);
}

Answer 1

I'm guessing under the hood this flag uses PendingIntent.equals, but I'm not really sure what criteria that function is using. Is it using the action, requestCode, categories, extras (I'm guessing no), etc.?

实际上提示在class描述中：

A description of an Intent and target action to perform with it. Instances of this class are created with

getActivity(android.content.Context,int,android.content.Intent,int), getActivities(android.content.Context,int,android.content.Intent[],int), getBroadcast(android.content.Context,int,android.content.Intent,int), getService(android.content.Context,int,android.content.Intent,int);

the returned object can be handed to other applications so that they can perform the action you described on your behalf at a later time.

By giving a PendingIntent to another application, you are granting it the right to perform the operation you have specified as if the other application was yourself (with the same permissions and identity). As such, you should be careful about how you build the PendingIntent: almost always, for example, the base Intent you supply should have the component name explicitly set to one of your own components, to ensure it is ultimately sent there and nowhere else.

A PendingIntent itself is simply a reference to a token maintained by the system describing the original data used to retrieve it. This means that, even if its owning application's process is killed, the PendingIntent itself will remain usable from other processes that have been given it. If the creating application later re-retrieves the same kind of PendingIntent (same operation, same Intent action, data, categories, and components, and same flags), it will receive a PendingIntent representing the same token if that is still valid, and can thus call cancel() to remove it.

Because of this behavior, it is important to know when two Intents are considered to be the same for purposes of retrieving a PendingIntent. A common mistake people make is to create multiple PendingIntent objects with Intents that only vary in their "extra" contents, expecting to get a different PendingIntent each time. This does not happen. The parts of the Intent that are used for matching are the same ones defined by Intent.filterEquals. If you use two Intent objects that are equivalent as per Intent.filterEquals, then you will get the same PendingIntent for both of them.

There are two typical ways to deal with this.

If you truly need multiple distinct PendingIntent objects active at the same time (such as to use as two notifications that are both shown at the same time), then you will need to ensure there is something that is different about them to associate them with different PendingIntents. This may be any of the Intent attributes considered by Intent.filterEquals, or different request code integers supplied to getActivity(android.content.Context,int,android.content.Intent,int), getActivities(android.content.Context,int,android.content.Intent[],int), getBroadcast(android.content.Context,int,android.content.Intent,int), or getService(android.content.Context,int,android.content.Intent,int).

If you only need one PendingIntent active at a time for any of the Intents you will use, then you can alternatively use the flags FLAG_CANCEL_CURRENT or FLAG_UPDATE_CURRENT to either cancel or modify whatever current PendingIntent is associated with the Intent you are supplying.

来自： http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/5.0.0_r1/android/app/PendingIntent.java#PendingIntent

Answer 2

要确定 2 PendingIntent 是否匹配，以下必须相等：

• 创建PendingIntent时使用的requestCode参数
• Intent 动作
• Intent 类别
• Intent 数据
• IntentMIMETYPE
• Intent 软件包
• Intent 组件

不考虑额外费用。

您可以在 PendingIntent summary documentation and Intent.filterEquals() 阅读更多内容。