从数据库中检索枚举列表时出现ClassCastException

Question

public class WebUser {

     @ElementCollection(targetClass = SecurityRole.class)
     @Enumerated(EnumType.STRING)
     @CollectionTable(name = "webRole_SecurityRole")
     @Column(name = "roles")
     private List<SecurityRole> securityRoles = new ArrayList<SecurityRole>();
}

我使用此命名查询检索用户安全角色：

      @NamedQuery(name=WebUser.GET_WEBUSER_SECURITYROLES,
                  query="select w.securityRoles from WebUser w where w.id=:id")

当迭代角色以使用foreach循环显示它们时：

List<SecurityRole> securityRoles = webUserFacade
                .findUserSecurityRoles("51");

        for (int i = 0; i < securityRoles.size(); i++) {
            System.out.println(securityRoles.get(i).getTitleResourceName());
        }

我遇到了这个异常： java.lang.ClassCastException：java.lang.String无法强制转换为com.myproject.SecurityRole

SecurityRole枚举：

public enum SecurityRole {

  private SecurityRole(String titleResourceName, String detailResourceName,
            String url, String iconName, SecurityRoleGroup securityRoleGroup) {
        this.detailResourceName = detailResourceName;
        this.url = url;
        this.titleResourceName = titleResourceName;
        this.iconName = iconName;
        this.securityRoleGroup = securityRoleGroup;
    }
//gettters 
}

我门面的findUserSecurityRoles方法：

public List<SecurityRole> findUserSecurityRoles(String id) {
        return getEntityManager().createNamedQuery(
                WebUser.GET_WEBUSER_SECURITYROLES, SecurityRole.class).setParameter("id", id)
                .getResultList();
    }