Android judges the strength of the wiff network signal

if (mNetworkType != null && mNetworkType == NetworkType.WIFI) {
            /**
             * 其中0到50表示信号最好，50到70表示信号偏差，大于70表示最差，有可能连接不上或者掉线。
             */
            int level = Math
                    .abs(((WifiManager) context.getSystemService(Context.WIFI_SERVICE)).getConnectionInfo().getRssi());

            if ((level - 50) <= 0) {// 0-50
                currentWifiSignal = NetWorkSignalDesc.WIFI_SIGNAL_INTENSITY_GOOD;
            } else if ((level - 70) <= 0) {// 50 -70
                currentWifiSignal = NetWorkSignalDesc.WIFI_SIGNAL_INTENSITY_BETTER;
            } else {
                currentWifiSignal = NetWorkSignalDesc.WIFI_SIGNAL_INTENSITY_BAD;
            }
        }