package com.example.floatdialogtest;  
  
import android.content.BroadcastReceiver;  
import android.content.Context;  
import android.content.Intent;  
import android.net.NetworkInfo;  
import android.net.wifi.WifiInfo;  
import android.net.wifi.WifiManager;  
  
public class WifiReceiver extends BroadcastReceiver{  
    @Override  
    public void onReceive(Context context, Intent intent) {  
        // TODO Auto-generated method stub  
        if(intent.getAction().equals(WifiManager.RSSI_CHANGED_ACTION)){  
            //signal strength changed  
        }  
        else if(intent.getAction().equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)){//wifi連線上與否  
            System.out.println("網路狀態改變");  
            NetworkInfo info = intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);  
            if(info.getState().equals(NetworkInfo.State.DISCONNECTED)){  
                System.out.println("wifi網路連線斷開");  
            }  
            else if(info.getState().equals(NetworkInfo.State.CONNECTED)){  
                  
                WifiManager wifiManager = (WifiManager)context.getSystemService(Context.WIFI_SERVICE);  
                WifiInfo wifiInfo = wifiManager.getConnectionInfo();                  
                  
                //獲取當前wifi名稱  
                System.out.println("連線到網路 " + wifiInfo.getSSID());  
                  
            }  
              
        }  
        else if(intent.getAction().equals(WifiManager.WIFI_STATE_CHANGED_ACTION)){//wifi開啟與否  
            int wifistate = intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE, WifiManager.WIFI_STATE_DISABLED);  
              
            if(wifistate == WifiManager.WIFI_STATE_DISABLED){  
                System.out.println("系統關閉wifi");  
            }  
            else if(wifistate == WifiManager.WIFI_STATE_ENABLED){  
                System.out.println("系統開啟wifi");  
            }  
        }  
    }  
} 
 

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

receiver intetfilter

<intent-filter >
                <action android:name="android.net.wifi.RSSI_CHANGED"/>
                <action android:name="android.net.wifi.STATE_CHANGE"/>
                <action android:name="android.net.wifi.WIFI_STATE_CHANGED"/>
</intent-filter>