public class SdcardStateReceiver extends BroadcastReceiver {
    private static final String TAG = "mylog";
    
    // 当sd状态发生改变的时候执行
    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.
//        throw new UnsupportedOperationException("Not yet implemented");
        //获取到当前广播的事件类型
        String action = intent.getAction();
        if ("android.intent.action.MEDIA_MOUNTED".equals(action)) {
            Log.d(TAG, "onReceive: SD卡挂载了"); 
        } else if ("android.intent.action.MEDIA_UNMOUNTED".equals(action)) {
            Log.d(TAG, "onReceive: SD卡卸载了");
        }
    }
}


<receiver
            android:name=".SdcardStateReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MEDIA_MOUNTED" />
                <action android:name="android.intent.action.MEDIA_UNMOUNTED" />
                <!--小细节 这里需要配置一个data 约束类型叫file 因为sd里面存的数据类型是file-->
                <data android:scheme="file" />
            </intent-filter>
        </receiver>