判断有没有网

public static void checkNetworkState(final Activity activity) {
// 1，判断有没有网
ConnectivityManager manager = (ConnectivityManager) activity
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = manager.getActiveNetworkInfo();
if (networkInfo == null) {
// 2,显示dialog
AlertDialog.Builder dialog = new AlertDialog.Builder(activity);
dialog.setMessage("亲，现在没网");
dialog.setPositiveButton("打开网络", new OnClickListener() {


@Override
public void onClick(DialogInterface dialog, int which) {
// 3,打开系统自带的网络设置activity
Intent intent = new Intent(
Settings.ACTION_WIRELESS_SETTINGS);
activity.startActivity(intent);
}
});


dialog.setNegativeButton("取消", new OnClickListener() {


@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});


dialog.show();


}