In spring security 3,how to customize my @ PreAuthorize annotation?

these days I meet a problem, I can not figure it out,so please help me...

My entity: Utilisateur this is a french word means user

    @Entity
    @Inheritance(strategy = InheritanceType.JOINED)
    public class Utilisateur implements Serializable 
    {
         private static final long serialVersionUID = 1L;
         @Id
         @GeneratedValue(strategy = GenerationType.IDENTITY)
         protected int id;
         protected String login;
         protected String password;
         protected String nom;
         protected String prenom;
         protected String email;
         protected String username;}

    @OneToOne(mappedBy="user", cascade={CascadeType.ALL})
    private Role role;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return login;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getLogin() {
        return login;
    }

    public void setLogin(String login) {
        this.login = login;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getNom() {
        return nom;
    }

    public void setNom(String nom) {
        this.nom = nom;
    }

    public String getPrenom() {
        return prenom;
    }

    public void setPrenom(String prenom) {
        this.prenom = prenom;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }



    public Role getRole() {
        return role;
    }

    public void setRole(Role role) {
        this.role = role;
    }
}

and a Role entity.

In my web app, there is a controller to show for example the information about a student(Etudiant in french)

@EJB(mappedName = "Etudiant.EtudiantFacade")
    EtudiantFacade etudiantF;

    // Affiche le detail d'un Etudiant  (show the infomations of the student)
    @RequestMapping(value = "/Etudiant/{idEtudiant}/info")
    public ModelAndView detail(@PathVariable String idEtudiant, Model m) {
        m.addAttribute("etudiant",
                etudiantF.trouver(Integer.parseInt(idEtudiant)));
        return new ModelAndView("EtudiantInformation", "null", null);
    }

I implemented my own CustomUseDetailService using the entity Utilisateur directly.

 @Override
    public UserDetails loadUserByUsername(String username)
            throws UsernameNotFoundException, DataAccessException {
        // TODO Auto-generated method stub
        System.out.println("!!!!!!!!!!!!!!!!!");
        System.out.println(username);

        boolean enabled = true;
        boolean accountNonExpired = true;
        boolean credentialsNonExpired = true;
        boolean accountNonLocked = true;

            Utilisateur etudiant = etudiantF.trouverParLogin(username);


            return new User(etudiant.getLogin(), etudiant.getPassword(), enabled,accountNonExpired,credentialsNonExpired,accountNonLocked,getAuthorities(etudiant.getRole().getRole()));

    }

and my security.xml is below:

<http auto-config="true" use-expressions="true">
        <intercept-url pattern="/app/Login" access="permitAll"/>
        <intercept-url pattern="/app/*" access="hasAnyRole('ROLE_ADMIN','ROLE_USER')"/>
        <form-login login-page="/app/Login" 
            authentication-success-handler-ref="authenticationSuccessHandler"/> 
        <logout logout-url="/app/Logout" logout-success-url="/"/>
    </http>

    <authentication-manager alias="authenticationManager">
        <authentication-provider user-service-ref="customUserDetailsService"/>
    </authentication-manager>

Last my question is: for a student, his id is 1, his username is stu1,to control this student with id 1 can only access his own page information /ProjetName/Student/{studentId}/Info how do I write the code with @PreAuthorize, I have see the document in form spring, there is example like @PreAuthorize(#contract.name = principal.username), because there is a attribute username in principal, but here,what I need is Id, I use @RequestMapping(value = "/Etudiant/{idEtudiant}/info") to match the student not the username. So how can I solve it? Many thanks... I can not find the tutorial.

You can provide your own implementation for User class (just extend org.springframework.security.core.userdetails.User). Add an identifier field to it. Then set corresponding value in loadUserByUsername method:

@Override
public UserDetails loadUserByUsername(String username)
    ...
    return new CustomUser(etudiant.getId(), etudiant.getLogin(), etudiant.getPassword(), enabled,accountNonExpired,credentialsNonExpired,accountNonLocked,getAuthorities(etudiant.getRole().getRole()));

}

Then you will be able to use it:

@PreAuthorize(#contract.name = principal.id)