关于Struts2中封装Form表单的问题

@Component("user")
@Scope("prototype")
public class UserAction extends ActionSupport implements ModelDriven {
    
    private UserRegisterInfo info = new UserRegisterInfo();
    
    private UserManager um;
    
    private List<User> users;
    
    
    
    public UserManager getUm() {
        return um;
    }
    
    @Resource(name="userManager")
    public void setUm(UserManager um) {
        this.um = um;
    }

    @Override
    public String execute() throws Exception {
        User u = new User();
        u.setUsername(info.getUsername());
        u.setPassword(info.getPassword());
        if(um.exists(u)) {
            return "fail";
        }
        um.add(u);
        return "success";
    }

    public UserRegisterInfo getInfo() {
        return info;
    }

    public void setInfo(UserRegisterInfo info) {
        this.info = info;
    }
    
    //@Override
    public Object getModel() {
        return info;
    }
    
    public String list() {
        this.users = this.um.getUsers();
        return "list";
    }
    
    public List<User> getUsers() {
        return users;
    }

    public void setUsers(List<User> users) {
        this.users = users;
    }

    
    
}