我想使用JPA执行以下选择:
select * from permissions_table where permissions.role in ("Role1", "Role2")
到目前为止我的样子是这样的:
protected Set<String> getPermissions(Connection conn, String username, Collection<String> roleNames) throws SQLException {
PreparedStatement ps = null;
Set<String> permissions = new LinkedHashSet<String>();
try {
EntityManager em = entityManagerFactory.createEntityManager();
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<HierarchicalPermission> criteria = builder.createQuery( HierarchicalPermission.class );
Root<HierarchicalPermission> permission = criteria.from(HierarchicalPermission.class);
criteria.select(permission).where(permission.get("Role").in(roleNames));
List<HierarchicalPermission> hPermissions = em.createQuery(criteria).getResultList();
for ( HierarchicalPermission p : hPermissions ) {
System.out.println( "Permission (" + p.getRole() +")");
}
}
catch(Exception ex)
{
System.out.println( ex.getMessage());
}
finally {
JdbcUtils.closeStatement(ps);
}
return permissions;
}
当我跨过这一行时:
List<HierarchicalPermission> hPermissions = em.createQuery(criteria).getResultList();
我在Eclipse输出窗口中看到以下内容:
Hibernate: select hierarchic0_.iIdentity as iIdentity0_, hierarchic0_.timestamp as timestamp0_, hierarchic0_.szRole as szRole0_, hierarchic0_.szDescription as szDescri4_0_, hierarchic0_.iResource as iResource0_ from occ.ROLE_PERMISSIONS hierarchic0_ where hierarchic0_.szRole in (?)
并且Eclipse调试器似乎停滞不前。此时,我只能暂停或停止执行,如此屏幕截图所示。
这是什么意思?这不是上述查询的有效表示吗?
答案 0 :(得分:0)
Sybase Interactive SQL在另一台机器上锁定了数据库,因此Hibernate在尝试执行查询时停滞不前。有人会认为Hibernate会抛出某种异常,而不是在遇到资源争用时暂停,但我想情况并非如此。