问如何为symfony2创建自定义用户提供程序？

EN

namespace CB\WebsiteBundle\Security;

use Symfony\Component\Security\Core\User\UserInterface;
use Symfony\Component\Security\Core\User\UserProviderInterface;
use Symfony\Component\Security\Core\Exception\UsernameNotFoundException;

use CB\WebsiteBundle\Entity\User;

class Provider implements UserProviderInterface {

    protected $user;
    public function __contsruct (UserInterface $user) {
        $this->user = $user;
    }

    /**
     * Loads the user for the given username.
     *
     * This method must throw UsernameNotFoundException if the user is not
     * found.
     *
     * @throws UsernameNotFoundException if the user is not found
     * @param string $username The username
     *
     * @return UserInterface
     */
    function loadUserByUsername($username) {
        $user = User::find(array('username'=>$username));
        if(empty($user)){
            throw new UsernameNotFoundException('Could not find user. Sorry!');
        }
        $this->user = $user;
        return $user;
    }

    /**
     * Refreshes the user for the account interface.
     *
     * It is up to the implementation if it decides to reload the user data
     * from the database, or if it simply merges the passed User into the
     * identity map of an entity manager.
     *
     * @throws UnsupportedUserException if the account is not supported
     * @param UserInterface $user
     *
     * @return UserInterface
     */
    function refreshUser(UserInterface $user) {
        return $user;
    }

    /**
     * Whether this provider supports the given user class
     *
     * @param string $class
     *
     * @return Boolean
     */
    function supportsClass($class) {
        return $class === 'MC\WebsiteBundle\Entity\User';
    }
}

<parameters>
    <parameter key="cb_security_user.class">CB\WebsiteBundle\Entity\User</parameter>
    <parameter key="cb_security_provider.class">CB\WebsiteBundle\Security\Provider</parameter>
</parameters>

<services>
    <service id="cb_security_user" class="%cb_security_user.class%" />
    <service id="cb_security_provider" class="%cb_security_provider.class%">
        <argument type="service" id="cb_security_user" />
    </service>
</services>