在Grails外部使用GORM时出现会话未找到错误

import org.grails.orm.hibernate.HibernateDatastore
import org.grails.orm.hibernate.SessionFactoryProxy

// 创建SessionFactory
def sessionFactory = new SessionFactoryProxy(grailsApplication.mainContext.sessionFactory)

// 创建Datastore
def datastore = new HibernateDatastore(sessionFactory)

// 创建会话
def session = datastore.connect()

import org.grails.orm.hibernate.HibernateCriteriaBuilder

// 创建CriteriaBuilder
def criteriaBuilder = new HibernateCriteriaBuilder(session)

// 执行查询
def results = criteriaBuilder.list {
    // 查询条件
    eq("name", "John")
}

session.disconnect()