Question

android 判断是否有网络连接

Answer 1

我们在做访问的时候都得进行判断是否连网。判断连网也比较简单，就用到了两个类。ConnectivityManager和NetworkInfo。

只要执行下面的代码就可以了。

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ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
boolean isWifiConn = networkInfo.isConnected();
networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
boolean isMobileConn = networkInfo.isConnected();

只要有一个连接就是有网，NetworkInfo就是网络的信息。还有一种更简便的判断是否连网的方法。

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ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

在一个就是监听网络变化，就是设置一个广播。

注册广播，监听ConnectivityManager.CONNECTIVITY_ACTION这个action

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IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
receiver = new NetworkReceiver();
context.registerReceiver(receiver, filter);

再实现一个广播类就可以了。这样网络一变化，就会受到广播，然后执行对应操作了。

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public class NetworkReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Log.i("TAG", "intent============>>>>" + intent.toString());

}
}

下面就是来说一下判断手机网络的类型了，2G，3G，4G

关于网络类型，在得到networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);这个后，确定是手机网络后，通过networkInfo.getSubtype()会得到网络的类型，用networkInfo.getSubtypeName()会得到网络的名字。

我们通过这个networkInfo.getSubtype()得到的类型来判断当前是什么网络。

其实，Android的Api中已经定义了各种网络状态，不是在ConnectivityManager里面定义的，而是在TelephonyManager里面的定义的。通过不同的api版本的修改，目前增加到了14个状态值：

下面是通过自己查资料，和看别人查资料实验得来的。整理如下：

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--------------------Added in API level 1---------------------
public static final int NETWORK_TYPE_UNKNOWN
Network type is unknown
Constant Value: 0 (0x00000000)
(不知道网络类型)

public static final int NETWORK_TYPE_GPRS
Current network is GPRS
Constant Value: 1 (0x00000001)
(2.5G）移动和联通

public static final int NETWORK_TYPE_EDGE
Current network is EDGE
Constant Value: 2 (0x00000002)
(2.75G)2.5G到3G的过渡 移动和联通

public static final int NETWORK_TYPE_UMTS
Current network is UMTS
Constant Value: 3 (0x00000003)
(3G)联通

-----------------Added in API level 4---------------------
public static final int NETWORK_TYPE_CDMA
Current network is CDMA: Either IS95A or IS95B
Constant Value: 4 (0x00000004)
(2G 电信)

public static final int NETWORK_TYPE_EVDO_0
Current network is EVDO revision 0
Constant Value: 5 (0x00000005)
( 3G )电信

public static final int NETWORK_TYPE_EVDO_A
Current network is EVDO revision A
Constant Value: 6 (0x00000006)
(3.5G) 属于3G过渡

public static final int NETWORK_TYPE_1xRTT
Current network is 1xRTT
Constant Value: 7 (0x00000007)
( 2G )

---------------------Added in API level 5--------------------
public static final int NETWORK_TYPE_HSDPA
Current network is HSDPA
Constant Value: 8 (0x00000008)
(3.5G )

public static final int NETWORK_TYPE_HSUPA
Current network is HSUPA
Constant Value: 9 (0x00000009)
( 3.5G )

public static final int NETWORK_TYPE_HSPA
Current network is HSPA
Constant Value: 10 (0x0000000a)
( 3G )联通

--------------------------Added in API level 8-------------------------
public static final int NETWORK_TYPE_IDEN
Current network is iDen
Constant Value: 11 (0x0000000b)
(2G )

--------------------------Added in API level 9-------------------------
public static final int NETWORK_TYPE_EVDO_B
Current network is EVDO revision B
Constant Value: 12 (0x0000000c)
3G-3.5G

--------------------------Added in API level 11------------------------
public static final int NETWORK_TYPE_LTE
Current network is LTE
Constant Value: 13 (0x0000000d)
(4G)

public static final int NETWORK_TYPE_EHRPD
Current network is eHRPD
Constant Value: 14 (0x0000000e)
3G(3G到4G的升级产物)

--------------------------Added in API level 13---------------------------
public static final int NETWORK_TYPE_HSPAP
Current network is HSPA+
Constant Value: 15 (0x0000000f)
( 3G )

Answer 2

ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = connectivity.getActiveNetworkInfo();
if(info != null && info.isAvailable()){
if (netInfo.getType() == ConnectivityManager.TYPE_WIFI) {
//WiFi网络
} else if (netInfo.getType() == ConnectivityManager.TYPE_MOBILE) {
//移动网络
} else {
//网络错误
}
}else{
//网络错误
}

Answer 3

用无线搜索啊！搜到了就显示了！现在Wi-Fi很多的！