AndroidPhoneStateListener.LISTEN_SIGNAL_STRENGTHS和TelephonyManager#requestCellInfoUpdate返回的信号强度不同

在Android设备上获取信号强度时，使用PhoneStateListener.LISTEN_SIGNAL_STRENGTHS和TelephonyManager#requestCellInfoUpdate返回的值可能不同。这是因为PhoneStateListener.LISTEN_SIGNAL_STRENGTHS返回当前连接的塔信号强度，而TelephonyManager#requestCellInfoUpdate返回不同基站的信号强度。

为了获得最新的信号强度值，请在onSignalStrengthsChanged回调中同时使用两个方法：

public class MyPhoneStateListener extends PhoneStateListener {

    @Override
    public void onSignalStrengthsChanged(SignalStrength signalStrength) {
        super.onSignalStrengthsChanged(signalStrength);

        TelephonyManager telephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
            telephonyManager.requestCellInfoUpdate(getMainExecutor(), new TelephonyManager.CellInfoCallback() {
                @Override
                public void onCellInfo(@NonNull List<CellInfo> cellInfo) {
                    for (CellInfo info : cellInfo) {
                        if (info instanceof CellInfoLte) {
                            CellSignalStrengthLte lte = ((CellInfoLte) info).getCellSignalStrength();
                            Log.d(TAG, "Lte signal strength: " + lte.getDbm());
                        } else if (info instanceof CellInfoGsm) {
                            CellSignalStrengthGsm gsm = ((CellInfoGsm) info).getCellSignalStrength();
                            Log.d(TAG, "Gsm signal strength: " + gsm.getDbm());
                        }
                    }
                }
            });
        }

        List<CellInfo> cellInfoList = telephonyManager.getAllCellInfo();
        for (CellInfo cellInfo : cellInfoList) {
            if (cellInfo instanceof CellInfoLte) {
                CellSignalStrengthLte lte = ((CellInfoLte) cellInfo).getCellSignalStrength();
                Log.d(TAG, "Lte signal strength: " + lte.getDbm());
            } else if (cellInfo instanceof CellInfoGsm) {
                CellSignalStrengthGsm gsm = ((CellInfoGsm) cellInfo).getCellSignalStrength();
                Log.d(TAG, "Gsm signal strength: " + gsm.getDbm());
            }
        }

    }
}

使用TelephonyManager#getCellSignalStrengths获取多个基站的信号强度，将所有信号强度平均后将其用于更准确的信号强度测量