判断当前网络类型（WIFI,2G,3G）

public class NetTestActivity extends Activity {         private static final int CMNET = 3;       private static final int CMWAP = 2;       private static final int WIFI = 1;         @Override       public void onCreate(Bundle savedInstanceState) {           super.onCreate(savedInstanceState);           setContentView(R.layout.main);           getAPNType(this);       }         /**        * 获取当前的网络状态 -1：没有网络 1：WIFI网络2：wap网络3：net网络        *         * @param context        * @return        */       public static int getAPNType(Context context) {           int netType = -1;           ConnectivityManager connMgr = (ConnectivityManager) context                   .getSystemService(Context.CONNECTIVITY_SERVICE);           NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();             if (networkInfo == null) {               return netType;           }           int nType = networkInfo.getType();           System.out.println("networkInfo.getExtraInfo() is "                  + networkInfo.getExtraInfo());           if (nType == ConnectivityManager.TYPE_MOBILE) {               if (networkInfo.getExtraInfo().toLowerCase().equals("cmnet")) {                   netType = CMNET;               } else {                   netType = CMWAP;               }           } else if (nType == ConnectivityManager.TYPE_WIFI) {               netType = WIFI;           }           return netType;       }   }