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

public class NetWorkStateReceiver extends BroadcastReceiver {
  @Override
  public void onReceive(Context context, Intent intent) {

    System.out.println("網絡狀態(tài)發(fā)生變化");
    //檢測API是不是小于23，因為到了API23之后getNetworkInfo(int networkType)方法被棄用
    if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.LOLLIPOP) {

      //獲得ConnectivityManager對象
      ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

      //獲取ConnectivityManager對象對應的NetworkInfo對象
      //獲取WIFI連接的信息
      NetworkInfo wifiNetworkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
      //獲取移動數據連接的信息
      NetworkInfo dataNetworkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
      if (wifiNetworkInfo.isConnected() && dataNetworkInfo.isConnected()) {
        Toast.makeText(context, "WIFI已連接,移動數據已連接", Toast.LENGTH_SHORT).show();
      } else if (wifiNetworkInfo.isConnected() && !dataNetworkInfo.isConnected()) {
        Toast.makeText(context, "WIFI已連接,移動數據已斷開", Toast.LENGTH_SHORT).show();
      } else if (!wifiNetworkInfo.isConnected() && dataNetworkInfo.isConnected()) {
        Toast.makeText(context, "WIFI已斷開,移動數據已連接", Toast.LENGTH_SHORT).show();
      } else {
        Toast.makeText(context, "WIFI已斷開,移動數據已斷開", Toast.LENGTH_SHORT).show();
      }
//API大于23時使用下面的方式進行網絡監(jiān)聽
    }else {

      System.out.println("API level 大于23");
      //獲得ConnectivityManager對象
      ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

      //獲取所有網絡連接的信息
      Network[] networks = connMgr.getAllNetworks();
      //用于存放網絡連接信息
      StringBuilder sb = new StringBuilder();
      //通過循環(huán)將網絡信息逐個取出來
      for (int i=0; i < networks.length; i++){
        //獲取ConnectivityManager對象對應的NetworkInfo對象
        NetworkInfo networkInfo = connMgr.getNetworkInfo(networks[i]);
        sb.append(networkInfo.getTypeName() + " connect is " + networkInfo.isConnected());
      }
      Toast.makeText(context, sb.toString(),Toast.LENGTH_SHORT).show();
    }
  }
}

public class MainActivity extends AppCompatActivity {

  NetWorkStateReceiver netWorkStateReceiver;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }

  //在onResume()方法注冊
  @Override
  protected void onResume() {
    if (netWorkStateReceiver == null) {
      netWorkStateReceiver = new NetWorkStateReceiver();
    }
    IntentFilter filter = new IntentFilter();
    filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
    registerReceiver(netWorkStateReceiver, filter);
    System.out.println("注冊");
    super.onResume();
  }

  //onPause()方法注銷
  @Override
  protected void onPause() {
    unregisterReceiver(netWorkStateReceiver);
    System.out.println("注銷");
    super.onPause();
  }
}

<receiver android:name=".NetWorkStateReceiver"> 
  <intent-filter> 
//檢測網絡變化的acton
    <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/> 
    <category android:name="android.intent.category.DEFAULT" /> 
  </intent-filter> 
</receiver>