1. 获取wifi信号强度

可以直接监听广播

MyReceiver receiver = new RssiReceiver();
IntentFilter intentFilter = new IntentFilter(WifiManager.RSSI_CHANGED_ACTION);
registerReceiver(receiver,intentFilter);class MyReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {int rssi = intent.getIntExtra(WifiManager.EXTRA_NEW_RSSI,-1);//这函数可以计算出信号的等级int strength = WifiManager.calculateSignalLevel(rssi, 5);}
}

也可以从NetworkCallback中获取

@RequiresApi(api = Build.VERSION_CODES.N)
private void registerNetwork(){ConnectivityManager connMgr = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {connMgr.registerDefaultNetworkCallback(new ConnectivityManager.NetworkCallback(){@Overridepublic void onAvailable(@NonNull Network network) {super.onAvailable(network);Log.d("NetworkCallback", "onAvailable: "+network);}@Overridepublic void onLinkPropertiesChanged(@NonNull Network network, @NonNull LinkProperties linkProperties) {super.onLinkPropertiesChanged(network, linkProperties);Log.d("NetworkCallback", "onLinkPropertiesChanged: "+network);}@Overridepublic void onCapabilitiesChanged(@NonNull Network network, @NonNull NetworkCapabilities networkCapabilities) {super.onCapabilitiesChanged(network, networkCapabilities);Log.d("NetworkCallback", "onCapabilitiesChanged: "+networkCapabilities.toString());if(networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)){//判断是wifi还是移动网络if(networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)){int strength = WifiManager.calculateSignalLevel(networkCapabilities.getSignalStrength(), 5);}else {}}}@Overridepublic void onLosing(@NonNull Network network, int maxMsToLive) {super.onLosing(network, maxMsToLive);Log.d("NetworkCallback", "onLosing: "+network);}@Overridepublic void onLost(@NonNull Network network) {super.onLost(network);Log.d("NetworkCallback", "onLost: "+network);}@Overridepublic void onUnavailable() {super.onUnavailable();Log.d("NetworkCallback", "onUnavailable: ");}});}
}

注意 networkCapabilities.getSignalStrength()在API29的时候才可以调用，低于29的时候为隐藏方法.可用反射调用。onCapabilitiesChanged这个函数在wifi强度变化时会调用，但是移动网络强度变化时确不会调用，而且在移动网络时getSignalStrength方法获取到的也不是信号强度。

2. 获取移动网络强度

可以直接监听PhoneStateListener，这里只是单卡的情况

private void phoneStateListener(){TelephonyManager mTelephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);mTelephonyManager.listen(new PhoneStateListener(){@RequiresApi(api = Build.VERSION_CODES.M)@Overridepublic void onSignalStrengthsChanged(SignalStrength signalStrength) {super.onSignalStrengthsChanged(signalStrength);int level = signalStrength.getLevel();Log.d("phoneStateListener", "onSignalStrengthsChanged: level "+level);}@Overridepublic void onServiceStateChanged(ServiceState state) {Log.d("phoneStateListener", "onServiceStateChanged: "+state.toString());}@Overridepublic void onDataConnectionStateChanged(int state, int networkType) {Log.d("phoneStateListener", "onDataConnectionStateChanged: state "+state+" networkType "+networkType);}}, PhoneStateListener.LISTEN_SIGNAL_STRENGTHS | PhoneStateListener.LISTEN_DATA_CONNECTION_STATE | PhoneStateListener.LISTEN_SERVICE_STATE);
}

如果是双卡的情况可以通过反射调用。但是我发现一个非常奇怪的现象，当打开相机时这里面的所有方法都会停止调用，原因不知道。没办法，只能取修改系统源码了，修改SystemUI的MobileSignalController.java

 @Overridepublic void onSignalStrengthsChanged(SignalStrength signalStrength) {if (DEBUG) {Log.d(mTag, "onSignalStrengthsChanged signalStrength=" + signalStrength +((signalStrength == null) ? "" : (" level=" + signalStrength.getLevel())));}mSignalStrength = signalStrength;updateTelephony();//信号有强度有变化时发送广播	Intent intent = new Intent("android.net.mobile.RSSI_CHANGED");intent.putExtra("EXTRA_NEW_RSSI", signalStrength.getLevel());mContext.sendBroadcast(intent);}