Android 广播 - 显式广播与隐式广播

测试引入

1、Receiver

java 复制代码

public class ExplicitAndImplicitReceiver extends BroadcastReceiver {

    public static final String TAG = ExplicitAndImplicitReceiver.class.getSimpleName();
    public static final String ACTION = "broadcast.ExplicitAndImplicitReceiver";

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i(TAG, "onReceive start");

        if (intent == null) {
            Log.i(TAG, "intent is null");
            return;
        }
        String action = 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 复制代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns: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">

    <Button
        android: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" />

    <Button
        android: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

java 复制代码

public class ExplicitAndImplicitReceiverTestActivity extends AppCompatActivity {

    public static final String TAG = ExplicitAndImplicitReceiverTestActivity.class.getSimpleName();

    private Button btnSendExplicitBroadcast;
    private Button btnSendImplicitBroadcast;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_explicit_and_implicit_receiver_test);
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
            return insets;
        });

        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");
            Intent intent = new Intent(this, ExplicitAndImplicitReceiver.class);
            sendBroadcast(intent);
        });

        btnSendImplicitBroadcast.setOnClickListener(v -> {
            Log.i(TAG, "发送隐式广播");
            Intent intent = new Intent(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

xml 复制代码

<receiver
    android: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

java 复制代码

public class ExplicitAndImplicitReceiver extends BroadcastReceiver {

    public static final String TAG = ExplicitAndImplicitReceiver.class.getSimpleName();

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i(TAG, "onReceive start");

        ...

        Log.i(TAG, "onReceive finish");
    }
}

xml 复制代码

<receiver
    android:name=".mybroadcast.ExplicitAndImplicitReceiver"
    android:exported="false" />

java 复制代码

Log.i(TAG, "发送显式广播");
Intent intent = new Intent(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

java 复制代码

public class ExplicitAndImplicitReceiver extends BroadcastReceiver {

    public static final String TAG = ExplicitAndImplicitReceiver.class.getSimpleName();
    public static final String ACTION = "broadcast.ExplicitAndImplicitReceiver";

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i(TAG, "onReceive start");

        if (intent == null) {
            Log.i(TAG, "intent is null");
            return;
        }
        String action = 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 复制代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns: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">

    <Button
        android: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" />

    <Button
        android: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

java 复制代码

public class ExplicitAndImplicitReceiverTestActivity extends AppCompatActivity {

    public static final String TAG = ExplicitAndImplicitReceiverTestActivity.class.getSimpleName();

    private ExplicitAndImplicitReceiver explicitAndImplicitReceiver;

    private Button btnSendExplicitBroadcast;
    private Button btnSendImplicitBroadcast;

    @Override
    protected void onStart() {
        super.onStart();

        explicitAndImplicitReceiver = new ExplicitAndImplicitReceiver();

        IntentFilter intentFilter = new IntentFilter(ExplicitAndImplicitReceiver.ACTION);

        registerReceiver(explicitAndImplicitReceiver, intentFilter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        if (explicitAndImplicitReceiver != null) unregisterReceiver(explicitAndImplicitReceiver);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_explicit_and_implicit_receiver_test);
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
            return insets;
        });

        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");
            Intent intent = new Intent(this, ExplicitAndImplicitReceiver.class);
            sendBroadcast(intent);
        });

        btnSendImplicitBroadcast.setOnClickListener(v -> {
            Log.i(TAG, "发送隐式广播");
            Intent intent = new Intent(ExplicitAndImplicitReceiver.ACTION);
            sendBroadcast(intent);
        });
    }
}

3、Test

（1）不指定 IntentFilter

java 复制代码

IntentFilter intentFilter = new IntentFilter();

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

java 复制代码

IntentFilter intentFilter = new IntentFilter(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）

Android 广播 - 显式广播与隐式广播

测试引入

1、Receiver

2、Activity

3、Test

（1）不声明 receiver

（2）声明 receiver，不声明 intent-filter

（3）声明 receiver，声明 intent-filter（匹配的 action）

理想情况

实际情况

（4）声明 receiver，声明 intent-filter（不匹配的 action）

理想情况

实际情况

测试结果分析

1、小结

2、实践

显式广播与隐式广播

Android 8.0+ 对隐式广播的限制

动态注册测试

1、Receiver

2、Activity

3、Test

（1）不指定 IntentFilter

（2）指定 IntentFilter

小结