检查网络是否可用

/**
* 检测网络是否可用1
* @param act
* @return
*/
public boolean isNetConnected(Activity act){

ConnectivityManager manager = (ConnectivityManager) act
.getApplicationContext().getSystemService(
Context.CONNECTIVITY_SERVICE);

if (manager == null) {
return false;
}
NetworkInfo networkinfo = manager.getActiveNetworkInfo();
if (networkinfo == null || !networkinfo.isAvailable()) {
return false;
}
return true;
}

/**
* 检測网络是否可用2
*/
private boolean isNetConnected() {
PppoeManager pppoeManager = PppoeManager.getInstance();
EthernetManager ethernetManager = EthernetManager.getInstance();
ConnectivityManager connectivityManager = (ConnectivityManager)
getSystemService(CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connectivityManager.getNetworkInfo
(ConnectivityManager.TYPE_WIFI);
if (networkInfo.isConnected() || ethernetManager.isNetworkConnected()
|| pppoeManager.getPppoeStatus().equals
(PppoeManager.PPPOE_STATE_CONNECT)) {
return true;
} else {
return false;
}
}