记录一下springside使用自定义查询的办法

 package org.springside.examples.miniweb.dao.account;

import java.util.List;

import javax.persistence.EntityManager;

import javax.persistence.PersistenceContext;

import org.springframework.stereotype.Component;

import org.springside.examples.miniweb.entity.account.Group;

import org.springside.examples.miniweb.entity.account.User;

/**

 * GroupDao的扩展行为实现类.

 */

@Component

public class GroupDaoImpl implements GroupDaoCustom {

private static final String QUERY_USER_BY_GROUPID = "select u from User u left join u.groupList g where g.id=?";

@PersistenceContext

private EntityManager em;

@Override

public void deleteWithReference(Long id) {

//因為Group中沒有与User的关联，只能用笨办法，查询出拥有该权限组的用户, 并删除该用户的权限组.

Group group = em.find(Group.class, id);

List<User> users = em.createQuery(QUERY_USER_BY_GROUPID).setParameter(1, id).getResultList();

for (User u : users) {

u.getGroupList().remove(group);

}

em.remove(group);

}

}