Android - 定期检查 WiFi 名称，直到出现条件

Question

我正在尝试构建一个提醒应用程序。 在这个应用程序中，用户将选择一个保存在手机上的 WiFi 名称。当用户连接到那个 WiFi 时，电话会振动。手机震动之后，服务就会死掉。

我尝试编写一个服务来每 1 分钟检查一次 WiFi 名称。当我关闭应用程序时，它会再次运行，但与我预期的不同。

服务实现：

public class AlarmService extends Service {
private static final String TAG = "com.wificheckalways";
public static String wifiToCheck = MainActivity.wifiName;

public AlarmService(){

}

public int onStartCommand(Intent intent, int flags, int startId){
    Log.i(TAG, "onStartCommand called");

    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            String ssid = "";
            ConnectivityManager connManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
            if (networkInfo.isConnected()) {
                final WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
                final WifiInfo connectionInfo = wifiManager.getConnectionInfo();
                if (connectionInfo != null && !TextUtils.isEmpty(connectionInfo.getSSID())) {
                    ssid = connectionInfo.getSSID();
                }
            }

            while(!wifiToCheck.equals(ssid)){
                Log.i(TAG, "Goes to SLEEP");
                synchronized (this){
                    try{
                        Thread.sleep(60000);
                        Log.i(TAG, "WAKE UP");
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                networkInfo = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
                if (networkInfo.isConnected()) {
                    final WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
                    final WifiInfo connectionInfo = wifiManager.getConnectionInfo();
                    if (connectionInfo != null && !TextUtils.isEmpty(connectionInfo.getSSID())) {
                        ssid = connectionInfo.getSSID();
                        Log.i(TAG, "Compare " + wifiToCheck + " with " + ssid);
                    }
                }

            }

            if(wifiToCheck.equals(ssid)) {
                Vibrator v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
                v.vibrate(2000); // 2000 miliseconds = 2 seconds
            }
        }
    };

    Thread alarmThread = new Thread(runnable);
    alarmThread.start();

    return Service.START_STICKY; //Restart service if it got destroyed
}

public void onDestroy(){
    Log.i(TAG, "onDestroyCommand called");
}

@Nullable
@Override
public IBinder onBind(Intent intent) {
    return null;
}

我在 MainActivity.java 中启动服务的地方：

public void SetAlarm(View view) {
    if (!wifiName.equals("")) {
        Toast.makeText(getApplicationContext(), "Alarm set for: " + wifiName, Toast.LENGTH_SHORT).show();

        Intent intent = new Intent(this, AlarmService.class);
        startService(intent);
    }
    else{
        Toast.makeText(getApplicationContext(), "Please choose a WiFi name!!!", Toast.LENGTH_SHORT).show();
    }
}

wifiName 是选择的 Wifi。

这段代码有什么问题？

Answer 1

正如我在 cmets 中所建议的，您的服务可能如下所示：

public class AlarmService extends Service {
    public AlarmService() {}

    @Override
    public void onCreate() {
        super.onCreate();
        IntentFilter intentFilter = new IntentFilter(WifiManager.NETWORK_STATE_CHANGED_ACTION);
        registerReceiver(receiver, intentFilter);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        unregisterReceiver(receiver);
    }

    private BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (action.equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
                NetworkInfo networkInfo = intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
                if (networkInfo.isConnected()) {
                    if (networkInfo.getType() == ConnectivityManager.TYPE_WIFI) {
                        WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
                        String ssid = wifiManager.getConnectionInfo().getSSID();
                        if (ssid.equals(<<ENTERED_SSID>>)) {
                            Vibrator vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
                            vibrator.vibrate(2000);
                            stopSelf();
                        }
                    }
                }
            }
        }
    };
} 

唯一“缺少”的部分是 SSID。

Answer 2

我猜你必须在 activty onPause() 或 onDestroy() 方法中停止服务，例如 stopService(new Intent(MainActivity.this,AlarmService.class));