PendingIntent描述了一個Intent和目標action。這個類的實例是用getActivity(Context,int,Intent,int)方法和getBroadcast(Context,int,Intent,int)和getService(Context,int,Intent,int)方法創建的。創建出的pending
intent可以交給其它程序，于是它們可以在以后的某個時間以你的名義執行intent中所描述的動作。

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通過給于一個PendingIntent，你可以使其它程序像你自己一樣執行你所指定的操作（具有相同的權限和身份）。所以，你需要小心的創建PendingIntent：通常，你最基本的應該明確設置你的相關組件的名字，以保證將來intent是被發送給它而不是其它地方。

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一個PendingIntent本是只是簡單地引用一個由系統維護的一個令牌，這個令牌描述了用于取得PendingIntent的原始數據。這表示即使擁有這個PendingIntent的進程關閉了，但這個PendingIntent對于那些收到它的進程依然有效。如果創建這個PendingIntent的程序又重新運行并重新獲取同一個類型的PendingIntent(相同的操作，action,數據，類型和組件以及相同的標志)，那么獲取的還是這個PendingIntent，并且這個程序可以用cancel()來刪除這個PendingIntent。

Intent和PendingIntent的區別?

intent英文意思是意圖，pending表示即將發生或來臨的事情。?
PendingIntent這個類用于處理即將發生的事情。比如在通知Notification中用于跳轉頁面，但不是馬上跳轉。?

Intent 是及時啟動，intent 隨所在的activity 消失而消失。?
PendingIntent 可以看作是對intent的包裝，通常通過getActivity,getBroadcast ,getService來得到pendingintent的實例，當前activity并不能馬上啟動它所包含的intent,而是在外部執行 pendingintent時，調用intent的。正由于pendingintent中
保存有當前App的Context，使它賦予外部App一種能力，使得外部App可以如同當前App一樣的執行pendingintent里的 Intent， 就算在執行時當前App已經不存在了，也能通過存在pendingintent里的Context照樣執行Intent。另外還可以處理intent執行后的操作。常和alermanger 和notificationmanager一起使用。?
Intent一般是用作Activity、Sercvice、BroadcastReceiver之間傳遞數據，而Pendingintent，一般用在 Notification上，可以理解為延遲執行的intent，PendingIntent是對Intent一個包裝。?

PendingIntent就是一個Intent的描述，我們可以把這個描述交給別的程序，別的程序根據這個描述在后面的別的時間做你安排做的事情 （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，就相當于PendingIntent代表了Intent）。

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用于描述Intent及其最終的行為.? 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于啟動一個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于啟動一個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于向BroadcastReceiver的Intent廣播的PendingIntent對象 返回的PendingIntent可以遞交給別的應用程序，然后繼續處理。這里的話你可以稍后才處理PendingIntent中描述的Intent及其最終行為。 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，你最好采用在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最后可能不知道發到哪里了。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，它描述了一些將用于retrieve的數據（這里，這些數據描述了Intent及其最終的行為）。 這就意味著即使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, 那么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，那么就將先將已有的PendingIntent取消，然后重新生成一個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()方法觸發過后，PendingIntent將自動調用cancel()進行銷毀，那么如果你再調用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，那么系統將使用該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于啟動一個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.

因為對于Context的startActivity方法，如果不是在其子類（Activity）中調用，那么必須對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 requestCode intent flags

The Context in which this PendingIntent should start the activity.

Private request code for the sender (currently not used).

Intent of the activity to be launched.

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 requestCode intents flags

The Context in which this PendingIntent should start the activity.

Private request code for the sender (currently not used).

Array of Intents of the activities to be launched.

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于啟動一個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 requestCode intent flags

The Context in which this PendingIntent should start the service.

Private request code for the sender (currently not used).

An Intent describing the service to be started.

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于向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 requestCode intent flags

The Context in which this PendingIntent should perform the broadcast.

Private request code for the sender (currently not used).

The Intent to be broadcast.

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 該系列主要用于觸發PendingIntent的Intent行為。用其Intent或啟動一個Activity，或啟動一個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 code intent

The Context of the caller. 該參數是因為intent參數才需要提供的，所用如果你的intent參數不為null的話，該參數也不能為null.

Result code to supply back to the PendingIntent's target.

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 onFinished handler

Result code to supply back to the PendingIntent's target.

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發送成功后的回調函數。

Handler identifying the thread on which the callback should happen. If null, the callback will happen from the thread pool of the process. 用于說明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 code intent onFinished handler

The Context of the caller. This may be null if?intent?is also null. 該參數是因為intent參數才需要提供的，一般是當前的context，如果你的intent參數不為null的話，該函數也不能為null.

Result code to supply back to the PendingIntent's target.

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.

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發送成功后的回調函數。

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.

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