void downloadFile()
{
sf::IpAddress address = "127.0.0.1";
sf::Ftp server;
sf::Ftp::Response connectResponse = server.connect(address);
if (!connectResponse.isOk())
{
//连接失败
}
// Ask for user name and password
std::string user = "test", password = "1234";
// Login to the server
sf::Ftp::Response loginResponse = server.login(user, password);
if (!loginResponse.isOk())
{
//登录失败
}