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這個類用於處理即將發生的事情。比如在通知Notification中用於跳轉頁面,但不是馬上跳轉。 

Intent 是及時啓動,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並不能馬上啓動它所包含的intent,而是在外部執行 pendingintent時,調用intent的。正由於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裏的 Intent, 就算在執行時當前App已經不存在了,也能通過存在pendingintent裏的Context照樣執行Intent。另外還可以處理intent執行後的操作。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,可以理解爲延遲執行的intent,PendingIntent是對Intent一個包裝。 

Java代碼 
  1. private void showNotify(){   
  2.         Notification notice=new Notification();   
  3.         notice.icon=R.drawable.icon;   
  4.         notice.tickerText="您有一條新的信息";   
  5.         notice.defaults=Notification.DEFAULT_SOUND;   
  6.         notice.when=10L;   
  7.         // 100 毫秒延遲後,震動 250 毫秒,暫停 100 毫秒後,再震動 500 毫秒     
  8.         //notice.vibrate = new long[] { 100, 250, 100, 500 };出錯?   
  9.         //notice.setLatestEventInfo(this, "通知", "開會啦", PendingIntent.getActivity(this, 0, null, 0));   
  10. notice.setLatestEventInfo(this"通知""開會啦", PendingIntent.getActivity(this0new Intent(this,Activity2.class), 0));//即將跳轉頁面,還沒跳轉   //PendingIntent.getActivity(this0new Intent(this,Activity2.class) 獲取 PendingIntent對象
  11.         
  12. NotificationManager manager=(NotificationManager)getSystemService(this.NOTIFICATION_SERVICE);   
  13.         manager.notify(0,notice);   //使用NotificationManager的時候 再去調用PendingIntent對象進行跳轉
  14.     }  


1. GSM網絡中android發送短信示例

Java代碼 
  1. String msg ="你好,美女";   
  2. String number = "135****6784";   
  3. SmsManager sms = SmsManager.getDefault();   
  4.   
  5. PendingIntent pi = PendingIntent.getBroadcast(SmsActivity.this,0,new Intent(...),0);   
  6. //new Intent(...)  e.g: PendingIntent pIntent = PendingIntent.getBroadcast(this, 0, new //// Intent("com.homer.pendingintent.pendingbroadcast"), 0);
  7. sms.sendTextMessage(number, null, msg, pi, null);   
  8. Toast.makeText(SmsActivity.this,"發送成功",Toast.LENGHT_LONG).show();  

完整例子,可以參考: http://download.csdn.net/detail/sunboy_2050/4917350#comment 

代碼解釋 
      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後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,就相當於PendingIntent代表了Intent)。本例中別的程序就是發送短信的程序,短信發送成功後要把intent廣播出去 。 
      函數SmsManager.sendTextMessage(String destinationAddress, String scAddress, String text, PendingIntent sentIntent, PendingIntent deliveryIntent)中參數解釋: 
      1)PendingIntent sentIntent:當短信發出時,成功的話sendIntent會把其內部的描述的intent廣播出去,否則產生錯誤代碼並通過android.app.PendingIntent.OnFinished進行回調,這個參數最好不爲空,否則會存在資源浪費的潛在問題; 
      2)PendingIntent deliveryIntent:是當消息已經傳遞給收信人後所進行的PendingIntent廣播。 
      查看PendingIntent 類可以看到許多的Send函數,就是PendingIntent在進行被賦予的相關的操作。


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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tokenPendingIntent。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
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_SHOTFLAG_NO_CREATEFLAG_CANCEL_CURRENTFLAG_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_SHOTFLAG_NO_CREATEFLAG_CANCEL_CURRENTFLAG_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_SHOTFLAG_NO_CREATEFLAG_CANCEL_CURRENTFLAG_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_SHOTFLAG_NO_CREATEFLAG_CANCEL_CURRENTFLAG_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.

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------

pendingIntent簡單理解 

pendingIntent字面意義:等待的,未決定的Intent。
要得到一個pendingIntent對象,使用方法類的靜態方法 getActivity(Context, int, Intent, int)getBroadcast(Context, int, Intent, int)getService(Context, int, Intent, int)  分別對應着Intent的3個行爲,跳轉到一個activity組件、打開一個廣播組件和打開一個服務組件。
參數有4個,比較重要的事第三個和第一個,其次是第四個和第二個。可以看到,要得到這個對象,必須傳入一個Intent作爲參數,必須有context作爲參數。
pendingIntent是一種特殊的Intent。主要的區別在於Intent的執行立刻的,而pendingIntent的執行不是立刻的。pendingIntent執行的操作實質上是參數傳進來的Intent的操作,但是使用pendingIntent的目的在於它所包含的Intent的操作的執行是需要滿足某些條件的。
主要的使用的地方和例子:通知Notificatio的發送,短消息SmsManager的發送和警報器AlarmManager的執行等等。

Android的狀態欄通知(Notification)

如果需要查看消息,可以拖動狀態欄到屏幕下方即可查看消息。

步驟:

獲取通知管理器NotificationManager,它也是一個系統服務

建立通知Notification notification = new Notification(icon, null, when);

爲新通知設置參數(比如聲音,震動,燈光閃爍)

把新通知添加到通知管理器

發送消息的代碼如下:

//獲取通知管理器

NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE)

int icon = android.R.drawable.stat_notify_chat;

long when = System.currentTimeMillis();//通知發生的時間爲系統當前時間

//新建一個通知,指定其圖標和標題

Notification notification = new Notification(icon, null, when);//第一個參數爲圖標,第二個參數爲短暫提示標題,第三個爲通知時間

notification.defaults = Notification.DEFAULT_SOUND;//發出默認聲音

notification.flags |= Notification.FLAG_AUTO_CANCEL;//點擊通知後自動清除通知

Intent openintent = new Intent(this, OtherActivity.class);

PendingIntent contentIntent = PendingIntent.getActivity(this, 0, openintent, 0);//當點擊消息時就會向系統發送openintent意圖

notification.setLatestEventInfo(this, “標題”, “我是內容", contentIntent);

mNotificationManager.notify(0, notification);//第一個參數爲自定義的通知唯一標識

 

重點是setLatestEventInfo( )方法的最後一個參數!!!!它是一個PendingIntent!!!!!!!!!

這裏使用到了PendingIntent(pend本意是待定,不確定的意思)

PendingIntent可以看作是對Intent的包裝。PendingIntent主要持有的信息是它所包裝的Intent和當前ApplicationContext。正由於PendingIntent中保存有當前ApplicationContext,使它賦予帶他程序一種執行的Intent的能力,就算在執行時當前Application已經不存在了,也能通過存在PendingIntent裏的Context照樣執行Intent

 

PendingIntent的一個很好的例子:

SmsManager的用於發送短信的方法:

sendTextMessage(destinationAddress, scAddress, text, sentIntent, deliveryIntent);

第一個參數:destinationAddress 對方手機號碼

第二個參數:scAddress 短信中心號碼 一般設置爲空

第三個參數:text 短信內容

第四個參數:sentIntent判斷短信是否發送成功,如果你沒有SIM卡,或者網絡中斷,則可以通過這個itent來判斷。注意強調的是“發送”的動作是否成功。那麼至於對於對方是否收到,另當別論

第五個參數:deliveryIntent當短信發送到收件人時,會收到這個deliveryIntent。即強調了“發送”後的結果

就是說是在"短信發送成功""對方收到此短信"纔會激活 sentIntentdeliveryIntent這兩個Intent。這也相當於是延遲執行了Intent


上面兩個例子可以理解,PendingIntent就是一個可以在滿足一定條件下執行的Intent,它相比於Intent的優勢在於自己攜帶有Context對象,這樣他就不必依賴於某個activity纔可以存在。

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