android-pendingintent

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本文翻譯整理自：http://developer.android.com/reference/android/app/PendingIntent.html

public final class

PendingIntent

extends Object

implements Parcelable

簡介

PendingIntent用於描述Intent及其最終的行爲. 

你可以通過getActivity(Context context, int requestCode, Intent intent, int flags)系列方法從系統取得一個用於啓動一個Activity的PendingIntent對象,

可以通過getService(Context context, int requestCode, Intent intent, int flags)方法從系統取得一個用於啓動一個Service的PendingIntent對象

可以通過getBroadcast(Context context, int requestCode, Intent intent, int flags)方法從系統取得一個用於向BroadcastReceiver的Intent廣播的PendingIntent對象

返回的PendingIntent可以遞交給別的應用程序，然後繼續處理。這裏的話你可以稍後才處理PendingIntent中描述的Intent及其最終行爲。

當你把PendingIntent遞交給別的程序進行處理時,PendingIntent仍然擁有PendingIntent原程序所擁有的權限(with the same permissions and identity).當你從系統取得一個PendingIntent時，一定要非常小心才行。比如，通常，如果Intent目的地是你自己的component（Activity/Service/BroadcastReceiver）的話，你最好採用在Intent中顯示指定目的component名字的方式，以確保Intent最終能發到目的，否則Intent最後可能不知道發到哪裏了。一個PendingIntent就是Android系統中的一個token（節點，這個應該是Linux或C\C++用語）的一個對象引用，它描述了一些將用於retrieve的數據（這裏，這些數據描述了Intent及其最終的行爲）。

這就意味着即使PendingIntent原進程結束了的話, PendingIntent本身仍然還存在，可在其他進程（PendingIntent被遞交到的其他程序）中繼續使用.如果我在從系統中提取一個PendingIntent的，而系統中有一個和你描述的PendingIntent對等的PendingInent, 那麼系統會直接返回和該PendingIntent其實是同一token的PendingIntent，而不是一個新的token和PendingIntent。然而你在從提取PendingIntent時，通過FLAG_CANCEL_CURRENT參數，讓這個老PendingIntent的先cancel()掉，這樣得到的pendingInten和其token的就是新的了。

通過FLAG_UPDATE_CURRENT參數的話，可以讓新的Intent會更新之前PendingIntent中的Intent對象數據，例如更新Intent中的Extras。另外，我們也可以在PendingIntent的原進程中調用PendingIntent的cancel ()把其從系統中移除掉。

注意：兩個PendingIntent對等是指它們的operation一樣, 且其它們的Intent的action, data, categories, components和flags都一樣。但是它們的Intent的Extra可以不一樣。

主要常量

FLAG_CANCEL_CURRENT:如果當前系統中已經存在一個相同的PendingIntent對象，那麼就將先將已有的PendingIntent取消，然後重新生成一個PendingIntent對象。

FLAG_NO_CREATE:如果當前系統中不存在相同的PendingIntent對象，系統將不會創建該PendingIntent對象而是直接返回null。

FLAG_ONE_SHOT:該PendingIntent只作用一次。在該PendingIntent對象通過send()方法觸發過後，PendingIntent將自動調用cancel()進行銷燬，那麼如果你再調用send()方法的話，系統將會返回一個SendIntentException。

FLAG_UPDATE_CURRENT:如果系統中有一個和你描述的PendingIntent對等的PendingInent，那麼系統將使用該PendingIntent對象，但是會使用新的Intent來更新之前PendingIntent中的Intent對象數據，例如更新Intent中的Extras。

主要成員函數

getActivities系列方法

該系列方法將從系統取得一個用於啓動一個Activity的PendingIntent對象。

public static PendingIntent getActivity (Context context, int requestCode, Intent intent, int flags)

Since: API Level 1

Retrieve a PendingIntent that will start a new activity, like calling Context.startActivity(Intent). Note that the activity will be started outside of the context of an existing activity, so you must use the Intent.FLAG_ACTIVITY_NEW_TASK launch flag in the Intent.

因爲對於Context的startActivity方法，如果不是在其子類（Activity）中調用，那麼必須對Intent加上FLAG_ACTIVITY_NEW_TASK。

具體可以參照Context中對startActivity方法的說明或《Activity和Task的基本模型》

Parameters

context	The Context in which this PendingIntent should start the activity.
requestCode	Private request code for the sender (currently not used).
intent	Intent of the activity to be launched.
flags	May be FLAG_ONE_SHOT, FLAG_NO_CREATE, FLAG_CANCEL_CURRENT, FLAG_UPDATE_CURRENT, or any of the flags as supported byIntent.fillIn() to control which unspecified parts of the intent that can be supplied when the actual send happens. 當我們使用Intent.fillIn()方法時，表示其Intent的某個數據項可以被send方法的Inent參數進行覆蓋重寫。

Returns

  Returns an existing or new PendingIntent matching the given parameters. May return null only if FLAG_NO_CREATE has been supplied.

public static PendingIntent getActivities (Context context, int requestCode, Intent[] intents, int flags)

Since: API Level 11

Like getActivity(Context, int, Intent, int), but allows an array of Intents to be supplied. The first Intent in the array is taken as the primary key for the PendingIntent, like the single Intent given to getActivity(Context, int, Intent, int). Upon sending the resulting PendingIntent, all of the Intents are started in the same way as they would be by passing them to startActivities(Intent[]).

The first intent in the array will be started outside of the context of an existing activity, so you must use the Intent.FLAG_ACTIVITY_NEW_TASK launch flag in the Intent. (Activities after the first in the array are started in the context of the previous activity in the array, so FLAG_ACTIVITY_NEW_TASK is not needed nor desired for them.)

The last intent in the array represents the key for the PendingIntent. In other words, it is the significant element for matching (as done with the single intent given togetActivity(Context, int, Intent, int), its content will be the subject of replacement by send(Context, int, Intent) andFLAG_UPDATE_CURRENT, etc. This is because it is the most specific of the supplied intents, and the UI the user actually sees when the intents are started.

Parameters

context	The Context in which this PendingIntent should start the activity.
requestCode	Private request code for the sender (currently not used).
intents	Array of Intents of the activities to be launched.
flags	May be FLAG_ONE_SHOT, FLAG_NO_CREATE, FLAG_CANCEL_CURRENT, FLAG_UPDATE_CURRENT, or any of the flags as supported byIntent.fillIn() to control which unspecified parts of the intent that can be supplied when the actual send happens. 當我們使用Inent.fillIn()所支持的flags時，表示其Intent的數據項可以被send方法的Intent參數覆蓋重寫。

Returns

• Returns an existing or new PendingIntent matching the given parameters. May return null only if FLAG_NO_CREATE has been supplied.

getService方法

該方法將系統取得一個用於啓動一個Service的PendingIntent對象.

public static PendingIntent getService (Context context, int requestCode, Intent intent, int flags)

Since: API Level 1

Retrieve a PendingIntent that will start a service, like calling Context.startService(). The start arguments given to the service will come from the extras of the Intent.

Parameters

context	The Context in which this PendingIntent should start the service.
requestCode	Private request code for the sender (currently not used).
intent	An Intent describing the service to be started.
flags	May be FLAG_ONE_SHOT, FLAG_NO_CREATE, FLAG_CANCEL_CURRENT, FLAG_UPDATE_CURRENT, or any of the flags as supported byIntent.fillIn() to control which unspecified parts of the intent that can be supplied when the actual send happens. 當我們使用Intent.fillIn()方法的flags時，它表示其Intent的數據項可以被send方法的Intent參數覆蓋重寫。

Returns

• Returns an existing or new PendingIntent matching the given parameters. May return null only if FLAG_NO_CREATE has been supplied.

getBroadcast方法

該方法將從系統取得一個用於向BroadcastReceiver的Intent廣播的PendingIntent對象

public static PendingIntent getBroadcast (Context context, int requestCode, Intent intent, int flags)

Since: API Level 1

Retrieve a PendingIntent that will perform a broadcast, like calling Context.sendBroadcast().

Parameters

context	The Context in which this PendingIntent should perform the broadcast.
requestCode	Private request code for the sender (currently not used).
intent	The Intent to be broadcast.
flags	May be FLAG_ONE_SHOT, FLAG_NO_CREATE, FLAG_CANCEL_CURRENT, FLAG_UPDATE_CURRENT, or any of the flags as supported byIntent.fillIn() to control which unspecified parts of the intent that can be supplied when the actual send happens. 當我們使用Intent.fillIn()方法的flags時，它表示其Intent的數據項可以被send方法的Intent參數覆蓋重寫。

Returns

• Returns an existing or new PendingIntent matching the given parameters. May return null only if FLAG_NO_CREATE has been supplied.

send系列方法

該系列主要用於觸發PendingIntent的Intent行爲。用其Intent或啓動一個Activity，或啓動一個Service，或向BroadcastReceiver發送Intent廣播。

public void send ()

Since: API Level 1

Perform the operation associated with this PendingIntent.

Throws

PendingIntent.CanceledException	Throws CanceledException if the PendingIntent is no longer allowing more intents to be sent through it.

public void send (Context context, int code, Intent intent)

Since: API Level 1

Perform the operation associated with this PendingIntent, allowing the caller to specify information about the Intent to use.

Parameters

context	The Context of the caller. 該參數是因爲intent參數才需要提供的，所用如果你的intent參數不爲null的話，該參數也不能爲null.
code	Result code to supply back to the PendingIntent's target.
intent	Additional Intent data. See Intent.fillIn() for information on how this is applied to the original Intent.

Throws

PendingIntent.CanceledException	Throws CanceledException if the PendingIntent is no longer allowing more intents to be sent through it.

public void send (int code, PendingIntent.OnFinished onFinished, Handler handler)

Since: API Level 1

Perform the operation associated with this PendingIntent, allowing the caller to be notified when the send has completed.

Parameters

code	Result code to supply back to the PendingIntent's target.
onFinished	The object to call back on when the send has completed, or null for no callback. 通過該參數，我們可以設置在Intent發送成功後的回調函數。
handler	Handler identifying the thread on which the callback should happen. If null, the callback will happen from the thread pool of the process. 用於說明onFinished參數指定的回調函數，最終在哪個Handler中進行調用。

Throws

PendingIntent.CanceledException	Throws CanceledException if the PendingIntent is no longer allowing more intents to be sent through it.

public void send (Context context, int code, Intent intent, PendingIntent.OnFinished onFinished, Handler handler)

Since: API Level 1

Perform the operation associated with this PendingIntent, allowing the caller to specify information about the Intent to use and be notified when the send has completed.

For the intent parameter, a PendingIntent often has restrictions on which fields can be supplied here, based on how the PendingIntent was retrieved ingetActivity(Context, int, Intent, int), getBroadcast(Context, int, Intent, int), or getService(Context, int, Intent, int).

Parameters

context	The Context of the caller. This may be null if intent is also null. 該參數是因爲intent參數才需要提供的，一般是當前的context，如果你的intent參數不爲null的話，該函數也不能爲null.
code	Result code to supply back to the PendingIntent's target.
intent	Additional Intent data. See Intent.fillIn() for information on how this is applied to the original Intent. Use null to not modify the original Intent.
onFinished	The object to call back on when the send has completed, or null for no callback. 通過該參數，我們可以指定Intent發送成功後的回調函數。
handler	Handler identifying the thread on which the callback should happen. If null, the callback will happen from the thread pool of the process. 該參數說明onFinished參數指定的回調函數將在哪個Handler中進行調用。

Throws

PendingIntent.CanceledException	Throws CanceledException if the PendingIntent is no longer allowing more intents to be sent through it.

cancel()函數

public void cancel ()

Since: API Level 1

Cancel a currently active PendingIntent. Only the original application owning an PendingIntent can cancel it.

只有PengdingIntent的原應用程序才能調用cancel()來把它從系統中移除掉。

getTargetPackage()函數

public String getTargetPackage ()

Since: API Level 1

Return the package name of the application that created this PendingIntent, that is the identity under which you will actually be sending the Intent. The returned string is supplied by the system, so that an application can not spoof its package.

Returns

• The package name of the PendingIntent, or null if there is none associated with it.