在獲取網路狀態前記得加上此許可權：

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

工具類如下：

public class NetworkUtil {
	
    private static final String TAG = NetworkUtil.class.getSimpleName();

    public enum NetType {
        None(1),
        Mobile(2),
        Wifi(4),
        Other(8);

        NetType(int value) {
            this.value = value;
        }

        public int value;
    }

    public enum NetWorkType {
        UnKnown(-1),
        Wifi(1),
        Net2G(2),
        Net3G(3),
        Net4G(4);

        NetWorkType(int value) {
            this.value = value;
        }

        public int value;
    }


    /**
     * 開啟網路設定介面
     * <p>3.0以下開啟設定介面</p>
     *
     * @param context 上下文
     */
    public static void openWirelessSettings(Context context) {
        if (android.os.Build.VERSION.SDK_INT > 10) {
            context.startActivity(new Intent(android.provider.Settings.ACTION_SETTINGS));
        } else {
            context.startActivity(new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS));
        }
    }

    /**
     * 獲取ConnectivityManager
     */
    public static ConnectivityManager getConnectivityManager(Context context) {
        return (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    }

    /**
     * 獲取TelephonyManager
     */
    public static TelephonyManager getTelephonyManager(Context context) {
        return (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
    }

    /**
     * 判斷網路連線是否有效（此時可傳輸資料）。
     *
     * @return boolean 不管wifi，還是mobile net，只有當前在連線狀態（可有效傳輸資料）才返回true,反之false。
     */
    public static boolean isConnected(Context context) {
        NetworkInfo net = getConnectivityManager(context).getActiveNetworkInfo();
        return net != null && net.isConnected();
    }

    /**
     * 判斷有無網路正在連線中（查詢網路、校驗、獲取IP等）。
     *
     * @return boolean 不管wifi，還是mobile net，只有當前在連線狀態（可有效傳輸資料）才返回true,反之false。
     */
    public static boolean isConnectedOrConnecting(Context context) {
        NetworkInfo[] nets = getConnectivityManager(context).getAllNetworkInfo();
        if (nets != null) {
            for (NetworkInfo net : nets) {
                if (net.isConnectedOrConnecting()) { return true; }
            }
        }
        return false;
    }

    public static NetType getConnectedType(Context context) {
        NetworkInfo net = getConnectivityManager(context).getActiveNetworkInfo();
        if (net != null) {
            switch (net.getType()) {
                case ConnectivityManager.TYPE_WIFI:
                    return NetType.Wifi;
                case ConnectivityManager.TYPE_MOBILE:
                    return NetType.Mobile;
                default:
                    return NetType.Other;
            }
        }
        return NetType.None;
    }

    /**
     * 是否存在有效的WIFI連線
     */
    public static boolean isWifiConnected(Context context) {
        NetworkInfo net = getConnectivityManager(context).getActiveNetworkInfo();
        return net != null && net.getType() == ConnectivityManager.TYPE_WIFI && net.isConnected();
    }

    /**
     * 是否存在有效的移動連線
     *
     * @return boolean
     */
    public static boolean isMobileConnected(Context context) {
        NetworkInfo net = getConnectivityManager(context).getActiveNetworkInfo();
        return net != null && net.getType() == ConnectivityManager.TYPE_MOBILE && net.isConnected();
    }

    /**
     * 檢測網路是否為可用狀態
     */
    public static boolean isAvailable(Context context) {
        return isWifiAvailable(context) || (isMobileAvailable(context) && isMobileEnabled(context));
    }

    /**
     * 判斷是否有可用狀態的Wifi，以下情況返回false：
     * 1. 裝置wifi開關關掉;
     * 2. 已經開啟飛航模式；
     * 3. 裝置所在區域沒有訊號覆蓋；
     * 4. 裝置在漫遊區域，且關閉了網路漫遊。
     *
     * @return boolean wifi為可用狀態（不一定成功連線，即Connected）即返回ture
     */
    public static boolean isWifiAvailable(Context context) {
        NetworkInfo[] nets = getConnectivityManager(context).getAllNetworkInfo();
        if (nets != null) {
            for (NetworkInfo net : nets) {
                if (net.getType() == ConnectivityManager.TYPE_WIFI) { return net.isAvailable(); }
            }
        }
        return false;
    }

    /**
     * 判斷有無可用狀態的行動網路，注意關掉裝置行動網路直接不影響此函式。
     * 也就是即使關掉行動網路，那麼行動網路也可能是可用的(彩信等服務)，即返回true。
     * 以下情況它是不可用的，將返回false：
     * 1. 裝置開啟飛航模式；
     * 2. 裝置所在區域沒有訊號覆蓋；
     * 3. 裝置在漫遊區域，且關閉了網路漫遊。
     *
     * @return boolean
     */
    public static boolean isMobileAvailable(Context context) {
        NetworkInfo[] nets = getConnectivityManager(context).getAllNetworkInfo();
        if (nets != null) {
            for (NetworkInfo net : nets) {
                if (net.getType() == ConnectivityManager.TYPE_MOBILE) { return net.isAvailable(); }
            }
        }
        return false;
    }

    /**
     * 裝置是否開啟行動網路開關
     *
     * @return boolean 開啟行動網路返回true，反之false
     */
    public static boolean isMobileEnabled(Context context) {
        try {
            Method getMobileDataEnabledMethod = ConnectivityManager.class.getDeclaredMethod("getMobileDataEnabled");
            getMobileDataEnabledMethod.setAccessible(true);
            return (Boolean) getMobileDataEnabledMethod.invoke(getConnectivityManager(context));
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 反射失敗，預設開啟
        return true;
    }

    /**
     * 列印當前各種網路狀態
     *
     * @return boolean
     */
    public static boolean printNetworkInfo(Context context) {
        ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectivity != null) {
            NetworkInfo in = connectivity.getActiveNetworkInfo();
            Log.i(TAG, "-------------$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$-------------");
            Log.i(TAG, "getActiveNetworkInfo: " + in);
            NetworkInfo[] info = connectivity.getAllNetworkInfo();
            if (info != null) {
                for (int i = 0; i < info.length; i++) {
                    // if (info[i].getType() == ConnectivityManager.TYPE_WIFI) {
                    Log.i(TAG, "NetworkInfo[" + i + "]isAvailable : " + info[i].isAvailable());
                    Log.i(TAG, "NetworkInfo[" + i + "]isConnected : " + info[i].isConnected());
                    Log.i(TAG, "NetworkInfo[" + i + "]isConnectedOrConnecting : " + info[i].isConnectedOrConnecting());
                    Log.i(TAG, "NetworkInfo[" + i + "]: " + info[i]);
                    // }
                }
                Log.i(TAG, "\n");
            } else {
                Log.i(TAG, "getAllNetworkInfo is null");
            }
        }
        return false;
    }

    /**
     * get connected network type by {@link ConnectivityManager}
     *
     * such as WIFI, MOBILE, ETHERNET, BLUETOOTH, etc.
     *
     * @return {@link ConnectivityManager#TYPE_WIFI}, {@link ConnectivityManager#TYPE_MOBILE},
     * {@link ConnectivityManager#TYPE_ETHERNET}...
     */
    public static int getConnectedTypeINT(Context context) {
        NetworkInfo net = getConnectivityManager(context).getActiveNetworkInfo();
        if (net != null) {
            Log.i(TAG, "NetworkInfo: " + net.toString());
            return net.getType();
        }
        return -1;
    }

    /**
     * get network type by {@link TelephonyManager}
     *
     * such as 2G, 3G, 4G, etc.
     *
     * @return {@link TelephonyManager#NETWORK_TYPE_CDMA}, {@link TelephonyManager#NETWORK_TYPE_GPRS},
     * {@link TelephonyManager#NETWORK_TYPE_LTE}...
     */
    public static int getTelNetworkTypeINT(Context context) {
        return getTelephonyManager(context).getNetworkType();
    }

    /**
     * GPRS    2G(2.5) General Packet Radia Service 114kbps
     * EDGE    2G(2.75G) Enhanced Data Rate for GSM Evolution 384kbps
     * UMTS    3G WCDMA 聯通3G Universal Mobile Telecommunication System 完整的3G移動通訊技術標準
     * CDMA    2G 電信 Code Division Multiple Access 分碼多重進接
     * EVDO_0  3G (EVDO 全程 CDMA2000 1xEV-DO) Evolution - Data Only (Data Optimized) 153.6kps - 2.4mbps 屬於3G
     * EVDO_A  3G 1.8mbps - 3.1mbps 屬於3G過渡，3.5G
     * 1xRTT   2G CDMA2000 1xRTT (RTT - 無線電傳輸技術) 144kbps 2G的過渡,
     * HSDPA   3.5G 高速下行分組接入 3.5G WCDMA High Speed Downlink Packet Access 14.4mbps
     * HSUPA   3.5G High Speed Uplink Packet Access 高速上行鏈路分組接入 1.4 - 5.8 mbps
     * HSPA    3G (分HSDPA,HSUPA) High Speed Packet Access
     * IDEN    2G Integrated Dispatch Enhanced Networks 整合數字增強型網路 （屬於2G，來自維基百科）
     * EVDO_B  3G EV-DO Rev.B 14.7Mbps 下行 3.5G
     * LTE     4G Long Term Evolution FDD-LTE 和 TDD-LTE , 3G過渡，升級版 LTE Advanced 才是4G
     * EHRPD   3G CDMA2000向LTE 4G的中間產物 Evolved High Rate Packet Data HRPD的升級
     * HSPAP   3G HSPAP 比 HSDPA 快些
     * 備註:在網路狀態變化時這個獲取的貌似不是很準確,有空除錯下...
     * @return {@link  NetWorkType}
     */
    public static NetWorkType getNetworkType(Context context) {
        int type = getConnectedTypeINT(context);
        switch (type) {
            case ConnectivityManager.TYPE_WIFI:
                return NetWorkType.Wifi;
            case ConnectivityManager.TYPE_MOBILE:
            case ConnectivityManager.TYPE_MOBILE_DUN:
            case ConnectivityManager.TYPE_MOBILE_HIPRI:
            case ConnectivityManager.TYPE_MOBILE_MMS:
            case ConnectivityManager.TYPE_MOBILE_SUPL:
                int teleType = getTelephonyManager(context).getNetworkType();
                switch (teleType) {
                    case TelephonyManager.NETWORK_TYPE_GPRS:
                    case TelephonyManager.NETWORK_TYPE_EDGE:
                    case TelephonyManager.NETWORK_TYPE_CDMA:
                    case TelephonyManager.NETWORK_TYPE_1xRTT:
                    case TelephonyManager.NETWORK_TYPE_IDEN:
                        return NetWorkType.Net2G;
                    case TelephonyManager.NETWORK_TYPE_UMTS:
                    case TelephonyManager.NETWORK_TYPE_EVDO_0:
                    case TelephonyManager.NETWORK_TYPE_EVDO_A:
                    case TelephonyManager.NETWORK_TYPE_HSDPA:
                    case TelephonyManager.NETWORK_TYPE_HSUPA:
                    case TelephonyManager.NETWORK_TYPE_HSPA:
                    case TelephonyManager.NETWORK_TYPE_EVDO_B:
                    case TelephonyManager.NETWORK_TYPE_EHRPD:
                    case TelephonyManager.NETWORK_TYPE_HSPAP:
                        return NetWorkType.Net3G;
                    case TelephonyManager.NETWORK_TYPE_LTE:
                        return NetWorkType.Net4G;
                    default:
                        return NetWorkType.UnKnown;
                }
            default:
                return NetWorkType.UnKnown;
        }
    }
}