Android監聽WIFI網絡的變化並且獲得當前信號強度

MainActivity如下:

    package cc.testwifi;  
      
    import android.os.Bundle;  
    import android.app.Activity;  
    /** 
     * Demo描述: 
     * 監聽Wifi網絡的變化並且獲得當前信號強度 
     *  
     * 
     */  
    public class MainActivity extends Activity {  
      
        @Override  
        protected void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.main);  
        }  
    }  

WifiChangeBroadcastReceiver如下:

    package cc.testwifi;  
      
    import android.content.BroadcastReceiver;  
    import android.content.Context;  
    import android.content.Intent;  
    import android.net.wifi.WifiInfo;  
    import android.net.wifi.WifiManager;  
      
    public class WifiChangeBroadcastReceiver extends BroadcastReceiver {  
        private Context mContext;  
        @Override  
        public void onReceive(Context context, Intent intent) {  
            mContext=context;  
            System.out.println("Wifi發生變化");  
            getWifiInfo();  
        }  
          
        private void getWifiInfo() {  
            WifiManager wifiManager = (WifiManager) mContext.getSystemService(mContext.WIFI_SERVICE);  
            WifiInfo wifiInfo = wifiManager.getConnectionInfo();  
            if (wifiInfo.getBSSID() != null) {  
                //wifi名稱  
                String ssid = wifiInfo.getSSID();  
                //wifi信號強度  
                int signalLevel = WifiManager.calculateSignalLevel(wifiInfo.getRssi(), 5);  
                //wifi速度  
                int speed = wifiInfo.getLinkSpeed();  
                //wifi速度單位  
                String units = WifiInfo.LINK_SPEED_UNITS;  
                System.out.println("ssid="+ssid+",signalLevel="+signalLevel+",speed="+speed+",units="+units);  
            }  
       }  
      
    }  

AndroidManifest.xml如下:

main.xml如下: