学习下Hibernate的Criteria

1. 方法说明

2，QBC常用限定方法

Restrictions.eq –> equal,等于.

Restrictions.allEq –> 参数为Map对象,使用key/value进行多个等于的比对,相当于多个Restrictions.eq的效果

Restrictions.gt –> great-than > 大于

Restrictions.ge –> great-equal >= 大于等于

Restrictions.lt –> less-than, < 小于

Restrictions.le –> less-equal <= 小于等于

Restrictions.between –> 对应SQL的between子句

Restrictions.like –> 对应SQL的LIKE子句

Restrictions.in –> 对应SQL的in子句

Restrictions.and –> and 关系

Restrictions.or –> or 关系

Restrictions.isNull –> 判断属性是否为空,为空则返回true

Restrictions.isNotNull –> 与isNull相反

Restrictions.sqlRestriction –> SQL限定的查询

Order.asc –> 根据传入的字段进行升序排序

Order.desc –> 根据传入的字段进行降序排序

MatchMode.EXACT –> 字符串精确匹配.相当于”like ‘value'”

MatchMode.ANYWHERE –> 字符串在中间匹配.相当于”like ‘%value%'”

MatchMode.START –> 字符串在最前面的位置.相当于”like ‘value%'”

MatchMode.END –> 字符串在最后面的位置.相当于”like ‘%value'”

例子
查询年龄在20-30岁之间的所有学生对象

List list = session.createCriteria(Student.class)
      .add(Restrictions.between("age",new Integer(20),new Integer(30)).list();

 
查询学生姓名在AAA,BBB,CCC之间的学生对象

String[] names = {"AAA","BBB","CCC"};
List list = session.createCriteria(Student.class)
      .add(Restrictions.in("name",names)).list();

 
查询年龄为空的学生对象

List list = session.createCriteria(Student.class)
      .add(Restrictions.isNull("age")).list();

 
查询年龄等于20或者年龄为空的学生对象

List list = session.createCriteria(Student.class)
      .add(Restrictions.or(Restrictions.eq("age",new Integer(20)),
                 Restrictions.isNull("age")).list();

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使用QBC实现动态查询

public List findStudents(String name,int age){

 Criteria criteria = session.createCriteria(Student.class);
 if(name != null){
  criteria.add(Restrictions.liek("name",name,MatchMode.ANYWHERE));
 }
 if(age != 0){
  criteria.add(Restrictions.eq("age",new Integer(age)));
 }
 criteria.addOrder(Order.asc("name"));//根据名字升序排列
 return criteria.list();
}

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今天用了写hibernate高级查询时用了Restrictions(当然Expression也是可以以的)这个类.感觉不错.
下面的代码写的不易读.其实核心就是一句
Restrictions.or(Restrictions.like(),Restrictions.or(Restrictions.like,……..))
里面的or可以无限加的.还是比较好用

Session session = getHibernateTemplate().getSessionFactory()
                .openSession();
        Criteria criteria = session.createCriteria(Film.class);
        List<Film> list = criteria.add(
            Restrictions.or(Restrictions.like("description", key,MatchMode.ANYWHERE),
            Restrictions.or(Restrictions.like("name", key,MatchMode.ANYWHERE),
                Restrictions.or(    Restrictions.like("direct", key,MatchMode.ANYWHERE),
                Restrictions.or(Restrictions.like("mainplay",key,MatchMode.ANYWHERE),
                        Restrictions.like("filearea", key,MatchMode.ANYWHERE)))))).list();

        session.close();
        return list;