AndroidCellularSignalStrength.java 文件源码

/**
 * Returns all observed cell information from all radios on the device including the primary
 * and neighboring cells. Returns only the information of cells that are registered to a
 * mobile network. May return {@code null}.
 */
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
private static List<CellInfo> getRegisteredCellInfo() {
    if (!isAPIAvailable()) {
        return null;
    }

    TelephonyManager telephonyManager =
            (TelephonyManager) ContextUtils.getApplicationContext().getSystemService(
                    Context.TELEPHONY_SERVICE);
    if (telephonyManager == null) {
        return null;
    }

    List<CellInfo> cellInfos = telephonyManager.getAllCellInfo();
    if (cellInfos == null) {
        return null;
    }

    Iterator<CellInfo> iter = cellInfos.iterator();
    while (iter.hasNext()) {
        if (!iter.next().isRegistered()) {
            iter.remove();
        }
    }
    return cellInfos;
}