android代码创建广播发送页面和广播接收器，演示如何发送广播和接收来自系统的广播。他的布局代码如何写

以下是一个简单的Android代码示例，展示了如何创建广播发送器和广播接收器，并演示了如何发送广播和接收来自系统的广播。

1. 广播发送器Activity的布局代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <Button
        android:id="@+id/btn_send_broadcast"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send Broadcast" />

</LinearLayout>

2. 广播发送器Activity的代码

public class BroadcastSenderActivity extends AppCompatActivity {

    private static final String ACTION_CUSTOM_BROADCAST = "com.example.broadcasttest.CUSTOM_BROADCAST";

    private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (ACTION_CUSTOM_BROADCAST.equals(action)) {
                String message = intent.getStringExtra("message");
                Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_broadcast_sender);

        IntentFilter filter = new IntentFilter(ACTION_CUSTOM_BROADCAST);
        registerReceiver(broadcastReceiver, filter);

        Button btnSendBroadcast = findViewById(R.id.btn_send_broadcast);
        btnSendBroadcast.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(ACTION_CUSTOM_BROADCAST);
                intent.putExtra("message", "Hello Receiver!");
                sendBroadcast(intent);
            }
        });
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(broadcastReceiver);
    }
}

3. 广播接收器的代码

public class CustomBroadcastReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if ("android.intent.action.AIRPLANE_MODE".equals(action)) {
            boolean isAirplaneModeOn = intent.getBooleanExtra("state", false);
            if (isAirplaneModeOn) {
                Toast.makeText(context, "Airplane mode is on", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(context, "Airplane mode is off", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

需要在AndroidManifest.xml中注册广播接收器：

<receiver android:name=".CustomBroadcastReceiver">
    <intent-filter>
        <action android:name="android.intent.action.AIRPLANE_MODE" />
    </intent-filter>
</receiver>

此示例中，我们创建了一个名为“ACTION_CUSTOM_BROADCAST”的自定义广播，并向其附加了一个包含“message”键和值“Hello Receiver！”的额外信息。发送广播时，我们使用“sendBroadcast（Intent）”方法。我们还创建了一个名为“broadcastReceiver”的广播接收器，并在其onReceive（）方法中进行处理。在此示例中，我们只是将消息字符串提取出来并将其显示为Toast通知。

此外，我们还创建了一个广播接收器来接收系统广播“android.intent.action.AIRPLANE_MODE”，并在其onReceive（）方法中进行处理。在此示例中，我们只是将“state”额外信息提取出来并将其显示为Toast通知。