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有序廣播怎么在Android應(yīng)用中進(jìn)行發(fā)送?相信很多沒有經(jīng)驗(yàn)的人對此束手無策,為此本文總結(jié)了問題出現(xiàn)的原因和解決方法,通過這篇文章希望你能解決這個問題。
Android系統(tǒng)提供了兩種廣播類型,一種是有序廣播,一種是有序廣播。
(1)無序廣播是完全異步執(zhí)行,發(fā)送廣播時所有監(jiān)聽這個廣播的廣播接收者都會收到此消息,但接收的順序不確定。
(2)有序廣播是按照接收者的優(yōu)先級接收,只有一個廣播接收者能接收信息,在此廣播接收者中邏輯執(zhí)行完畢后,才會繼續(xù)傳遞。
實(shí)驗(yàn)要求:通過sendOrderedBroadeast()發(fā)送一條有序廣播
1.在activity-main.xml布局文件中代碼如下:
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:background="@drawable/stitch_one" tools:context="cn.edu.bzu.orderedbroadcast.MainActivity"> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:onClick="send" android:layout_marginTop="50dp" android:text="發(fā)送有序廣播" android:paddingLeft="5dp" android:paddingRight="5dp" android:background="#FFD202" android:textSize="20sp" /> </RelativeLayout>
2.在MainActivity中代碼如下:
package cn.edu.bzu.orderedbroadcast; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void send(View view){ Intent intent=new Intent(); //定義廣播事件類型 intent.setAction("Intercept_Stitch"); //發(fā)送廣播 sendOrderedBroadcast(intent,null); } }
3.創(chuàng)建三個廣播接收者
(1)MyBroadcastReceiverOne
(2)MyBroadcastReceiverTwo
(3)MyBroadcastReceiverThree
(1)在MyBroadcastReceiverOne中代碼如下:
package cn.edu.bzu.orderedbroadcast; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.util.Log; public class MyBroadcastReceiverOne extends BroadcastReceiver { public MyBroadcastReceiverOne() { } @Override public void onReceive(Context context, Intent intent) { Log.i("MyBroadcastReceiverOne","自定義的廣播接收者one,接收到了廣播事件"); } }
(2)在MyBroadcastReceiverTwo中代碼如下:
package cn.edu.bzu.orderedbroadcast; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.util.Log; public class MyBroadcastReceiverTwo extends BroadcastReceiver { public MyBroadcastReceiverTwo() { } @Override public void onReceive(Context context, Intent intent) { Log.i("MyBroadcastReceiverTwo","自定義的廣播接收者Two,接收到了廣播事件"); } }
(3)在MyBroadcastReceiverThree中代碼如下:
package cn.edu.bzu.orderedbroadcast; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.util.Log; public class MyBroadcastReceiverThree extends BroadcastReceiver { public MyBroadcastReceiverThree() { } @Override public void onReceive(Context context, Intent intent) { Log.i("MyBroadcastReceiverThree","自定義的廣播接收者Three,接收到了廣播事件"); } }
4.在配置文件AndroidManifest中代碼如下:
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="cn.edu.bzu.orderedbroadcast"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <receiver android:name=".MyBroadcastReceiverOne"> <intent-filter android:priority="1000"> <action android:name="Intercept_Stitch"/> </intent-filter> </receiver> <receiver android:name=".MyBroadcastReceiverTwo"> <intent-filter android:priority="200"> <action android:name="Intercept_Stitch"/> </intent-filter> </receiver> <receiver android:name=".MyBroadcastReceiverThree"> <intent-filter android:priority="600"> <action android:name="Intercept_Stitch"/> </intent-filter> </receiver> </application> </manifest>
5.實(shí)驗(yàn)效果圖:
運(yùn)行程序后解決如下問題:
問題1:程序啟動后,單擊“發(fā)送有序廣播”按鈕,發(fā)出一條廣播事件,此時觀察LogCat窗口下的提示信息,輸出什么?為什么?
點(diǎn)擊按鈕后出現(xiàn)如下圖所示提示信息,原因是有序廣播根據(jù)優(yōu)先級接收廣播信息的,在配置文件中廣播接收者One的priority值最大,所以它先接收到廣播,其次是Three,最后是Two。其中android:priority="值"是用來設(shè)置廣播接收者的優(yōu)先級的,值越大,優(yōu)先級別越高。
問題2:若將廣播接收者M(jìn)yBroadcastReceiverTwo優(yōu)先級同樣設(shè)置為1000,并將MyBroadcastReceiverTwo注冊在MyBroadcastReceiverOne前面,再來運(yùn)行程序,觀察結(jié)果,你能得出什么結(jié)論?
修改配置文件AndroidManifest中代碼如下:
<receiver android:name=".MyBroadcastReceiverTwo"> <intent-filter android:priority="1000"> <action android:name="Intercept_Stitch"/> </intent-filter> </receiver> <receiver android:name=".MyBroadcastReceiverOne"> <intent-filter android:priority="1000"> <action android:name="Intercept_Stitch"/> </intent-filter> </receiver> <receiver android:name=".MyBroadcastReceiverThree"> <intent-filter android:priority="600"> <action android:name="Intercept_Stitch"/> </intent-filter> </receiver>
運(yùn)行程序出現(xiàn)如下圖所示提示信息,原因是當(dāng)廣播接收者的優(yōu)先級別相同時,先注冊的廣播接收者先接收到廣播。
問題3:修改MyBroadcastReceiverTwo如下,觀察結(jié)果,你又可以得出什么結(jié)論?
public class MyBroadcastReceiverTwo extends BroadcastReceiver { public MyBroadcastReceiverTwo() { } @Override public void onReceive(Context context, Intent intent) { Log.i("MyBroadcastReceiverTwo","自定義的廣播接收者Two,接收到了廣播事件"); abortBroadcast();//有序廣播攔截器 Log.i("MyBroadcastReceiverTwo","我是廣播接收者Two,廣播被我終止了"); } }
運(yùn)行程序出現(xiàn)如下圖所示提示信息,原因是廣播接收者Two的優(yōu)先級最高,所以在Two中寫一個攔截器,優(yōu)先級低的廣播接收者將接收不到廣播信息,所以O(shè)ne和Three沒有接收到廣播事件,也就沒有打印關(guān)于它們的信息。
看完上述內(nèi)容,你們掌握有序廣播怎么在Android應(yīng)用中進(jìn)行發(fā)送的方法了嗎?如果還想學(xué)到更多技能或想了解更多相關(guān)內(nèi)容,歡迎關(guān)注億速云行業(yè)資訊頻道,感謝各位的閱讀!
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