Android 广播 - 显式广播与隐式广播
测试引入
1、Receiver
publicclassExplicitAndImplicitReceiverextendsBroadcastReceiver{publicstaticfinalStringTAG=ExplicitAndImplicitReceiver.class.getSimpleName();publicstaticfinalStringACTION="broadcast.ExplicitAndImplicitReceiver";@OverridepublicvoidonReceive(Contextcontext,Intentintent){Log.i(TAG,"onReceive start");if(intent==null){Log.i(TAG,"intent is null");return;}Stringaction=intent.getAction();if(action==null){Log.i(TAG,"action is null");return;}if(!action.equals(ACTION)){Log.i(TAG,"action is not "+ACTION);return;}Log.i(TAG,"onReceive finish");}}2、Activity
- activity_explicit_and_implicit_receiver_test.xml
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayoutxmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:id="@+id/main"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".ExplicitAndImplicitReceiverTestActivity"><Buttonandroid:id="@+id/btn_send_explicit_broadcast"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="发送显式广播"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent"/><Buttonandroid:id="@+id/btn_send_implicit_broadcast"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="发送隐式广播"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/btn_send_explicit_broadcast"/></androidx.constraintlayout.widget.ConstraintLayout>- ExplicitAndImplicitReceiverTestActivity.java
publicclassExplicitAndImplicitReceiverTestActivityextendsAppCompatActivity{publicstaticfinalStringTAG=ExplicitAndImplicitReceiverTestActivity.class.getSimpleName();privateButtonbtnSendExplicitBroadcast;privateButtonbtnSendImplicitBroadcast;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);EdgeToEdge.enable(this);setContentView(R.layout.activity_explicit_and_implicit_receiver_test);ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main),(v,insets)->{InsetssystemBars=insets.getInsets(WindowInsetsCompat.Type.systemBars());v.setPadding(systemBars.left,systemBars.top,systemBars.right,systemBars.bottom);returninsets;});btnSendExplicitBroadcast=findViewById(R.id.btn_send_explicit_broadcast);btnSendImplicitBroadcast=findViewById(R.id.btn_send_implicit_broadcast);btnSendExplicitBroadcast.setOnClickListener(v->{Log.i(TAG,"发送显式广播");Intentintent=newIntent(this,ExplicitAndImplicitReceiver.class);sendBroadcast(intent);});btnSendImplicitBroadcast.setOnClickListener(v->{Log.i(TAG,"发送隐式广播");Intentintent=newIntent(ExplicitAndImplicitReceiver.ACTION);sendBroadcast(intent);});}}3、Test
（1）不声明 receiver
- 发送显式广播，输出结果
发送显式广播- 发送隐式广播，输出结果
发送隐式广播（2）声明 receiver，不声明 intent-filter
<receiverandroid:name=".mybroadcast.ExplicitAndImplicitReceiver"android:exported="false"/>- 发送显式广播，输出结果
发送显式广播 onReceive start action is null- 发送隐式广播，输出结果
发送隐式广播（3）声明 receiver，声明 intent-filter（匹配的 action）
- 发送显式广播，输出结果
发送显式广播 onReceive start action is null- 发送隐式广播，输出结果
# 理想情况 发送隐式广播 onReceive start onReceive finish# 实际情况 发送隐式广播（4）声明 receiver，声明 intent-filter（不匹配的 action）
- 发送显式广播，输出结果
发送显式广播 onReceive start action is null- 发送隐式广播，输出结果
# 理想情况 发送隐式广播 onReceive start action is not broadcast.ExplicitAndImplicitReceiver# 实际情况 发送隐式广播测试结果分析
1、小结
| 测试 | Receiver | intent-filter | 显式广播结果 | 隐式广播结果 | 原因 |
|---|---|---|---|---|---|
| 1 | 无 | 无 | 收不到 | 收不到 | 未注册 Receiver |
| 2 | 有 | 无 | 收到 | 收不到 | 隐式广播在 Android 8.0+ 被限制 |
| 3 | 有 | 有，匹配的 action | 收到 | 收不到 | 隐式广播在 Android 8.0+ 被限制 |
| 4 | 有 | 有，不匹配的 action | 收到 | 收不到 | 隐式广播在 Android 8.0+ 被限制 |
静态注册的 Receiver 使用显式广播
可以不加 intent-filter（加不加都可以收到）
Receiver 内可以不检查 action，直接接收广播
如果要检查 action（区分多个 action），显式广播的 Intent 中需要包含 action
2、实践
publicclassExplicitAndImplicitReceiverextendsBroadcastReceiver{publicstaticfinalStringTAG=ExplicitAndImplicitReceiver.class.getSimpleName();@OverridepublicvoidonReceive(Contextcontext,Intentintent){Log.i(TAG,"onReceive start");...Log.i(TAG,"onReceive finish");}}<receiverandroid:name=".mybroadcast.ExplicitAndImplicitReceiver"android:exported="false"/>Log.i(TAG,"发送显式广播");Intentintent=newIntent(this,ExplicitAndImplicitReceiver.class);sendBroadcast(intent);显式广播与隐式广播
| - | 显式广播 | 隐式广播 |
|---|---|---|
| 目标指定 | 明确指定接收者类名 | 不指定接收者，通过 IntentFilter 匹配 |
| 接收范围 | 只能被指定的接收者接收 | 可以被多个接收者接收 |
| 安全系数 | 较高，只能被指定接收者接收 | 较低，可能被其他应用接收 |
| 应用场景 | 应用内组件通信 | 系统广播、跨应用通信 |
Android 8.0+ 对隐式广播的限制
从 Android 8.0（API 26）开始，静态注册的广播接收器无法接收大多数隐式广播
除非是豁免的广播，例如，系统广播
动态注册测试
1、Receiver
publicclassExplicitAndImplicitReceiverextendsBroadcastReceiver{publicstaticfinalStringTAG=ExplicitAndImplicitReceiver.class.getSimpleName();publicstaticfinalStringACTION="broadcast.ExplicitAndImplicitReceiver";@OverridepublicvoidonReceive(Contextcontext,Intentintent){Log.i(TAG,"onReceive start");if(intent==null){Log.i(TAG,"intent is null");return;}Stringaction=intent.getAction();if(action==null){Log.i(TAG,"action is null");return;}if(!action.equals(ACTION)){Log.i(TAG,"action is not "+ACTION);return;}Log.i(TAG,"onReceive finish");}}2、Activity
- activity_explicit_and_implicit_receiver_test.xml
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayoutxmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:id="@+id/main"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".ExplicitAndImplicitReceiverTestActivity"><Buttonandroid:id="@+id/btn_send_explicit_broadcast"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="发送显式广播"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent"/><Buttonandroid:id="@+id/btn_send_implicit_broadcast"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="发送隐式广播"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/btn_send_explicit_broadcast"/></androidx.constraintlayout.widget.ConstraintLayout>- ExplicitAndImplicitReceiverTestActivity.java
publicclassExplicitAndImplicitReceiverTestActivityextendsAppCompatActivity{publicstaticfinalStringTAG=ExplicitAndImplicitReceiverTestActivity.class.getSimpleName();privateExplicitAndImplicitReceiverexplicitAndImplicitReceiver;privateButtonbtnSendExplicitBroadcast;privateButtonbtnSendImplicitBroadcast;@OverrideprotectedvoidonStart(){super.onStart();explicitAndImplicitReceiver=newExplicitAndImplicitReceiver();IntentFilterintentFilter=newIntentFilter(ExplicitAndImplicitReceiver.ACTION);registerReceiver(explicitAndImplicitReceiver,intentFilter);}@OverrideprotectedvoidonDestroy(){super.onDestroy();if(explicitAndImplicitReceiver!=null)unregisterReceiver(explicitAndImplicitReceiver);}@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);EdgeToEdge.enable(this);setContentView(R.layout.activity_explicit_and_implicit_receiver_test);ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main),(v,insets)->{InsetssystemBars=insets.getInsets(WindowInsetsCompat.Type.systemBars());v.setPadding(systemBars.left,systemBars.top,systemBars.right,systemBars.bottom);returninsets;});btnSendExplicitBroadcast=findViewById(R.id.btn_send_explicit_broadcast);btnSendImplicitBroadcast=findViewById(R.id.btn_send_implicit_broadcast);btnSendExplicitBroadcast.setOnClickListener(v->{Log.i(TAG,"发送显式广播");Intentintent=newIntent(this,ExplicitAndImplicitReceiver.class);sendBroadcast(intent);});btnSendImplicitBroadcast.setOnClickListener(v->{Log.i(TAG,"发送隐式广播");Intentintent=newIntent(ExplicitAndImplicitReceiver.ACTION);sendBroadcast(intent);});}}3、Test
（1）不指定 IntentFilter
IntentFilterintentFilter=newIntentFilter();- 发送显式广播，输出结果
发送显式广播- 发送隐式广播，输出结果
发送隐式广播（2）指定 IntentFilter
IntentFilterintentFilter=newIntentFilter(ExplicitAndImplicitReceiver.ACTION);- 发送显式广播，输出结果
发送显式广播- 发送隐式广播，输出结果
发送隐式广播 onReceive start onReceive finish小结
动态注册的 Receiver 使用隐式广播
指定 IntentFilter
Receiver 内可以不检查 action，直接接收广播（一个 action 的情况）