Criteria:代表一次查询
Criterion:代表一个查询条件
Restrictions:产生查询条件的工具类
执行条件查询的步骤如下:
(1)获得Hibernate的Session对象
(2)以Session对象创建Criteria对象
(3)增加Criterion查询条件
(4)执行Criteria的list等方法返回结果集
请看示例:
private void test()
{
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//创建Criteria和添加查询条件同步完成
//最后调用list方法,返回查询到的结果集
List l = session.createCriteria(Student.class)
//此处增加到限制条件必须是Student已经存在的属性
.add(Restritions.gt("studentNumber", new Long(20071127)))
//如果要增加对Student关联类的属性限制,则必须重新创建
//如果此关联属性是集合,则只要集合里任意一个对象的属性满足下面条件即可
.createCriteria("enrolments")
.add(Restritions.gt("semester", new Short("2")))
.list();
Iterator it = l.iterator();
//遍历查询到的记录
while (it.hasNext())
{
Student s = (Student)it.next();
System.out.println(s.getName());
Set enrolments = s.getEnrolments();
Iterator iter = enrolments.iterator();
while (iter.hasNext())
{
Enrolment e = (Enrolment)iter.next();
System.out.println(e.getCourse().getName());
}
}
tx.commit();
HibernateUtil.closeSession();
}
session.createCriteria(Person.class)
.add(Restrictions.like("name", "dd%"))
.createCriteria("address")
.add(Restrictions.like("addressdetail", "福州%"))
.list();
比Query多了两个重载的构造方法
addEntity:将查询到的记录与特定的实体关联
addScalar:将查询到的记录关联成标量值
执行SQL查询的步骤如下:
(1)获取Hibernate Session对象
(2)编写SQL语句
(3)以SQL语句作为参数,调用Session的createSQLQuery方法创建查询对象
(4)如果SQL语句包含参数,则调用Query的setXxx方法为参数赋值
(5)调用SQLQuery对象的addEntiy或addScalar方法,将选出的结果与实体或标量值关联
(6)调用Query的list方法返回查询的结果集
请看SQL的查询示例:
private void test() {
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//编写SQL语句
String sqlString = "select {s.*} from student s where s.name like '李四'";
//以SQL语句创建SQLQuery对象
List l = session.createSQLQuery(sqlString)
//将查询到的记录与特定实体关联起来
.addEntity("s", Student.class)
//返回全部的记录集
.list();
Iterator it = l.iterator();
while (it.hasNext())
{
//因为将查询的结果与Student类关联,因此返回时Student的集合
Student s = (Student)it.next();
Set enrolments = s.getEnrolmens();
Iterator iter = enrolments.iterator();
while (iter.hasNext())
{
Enrolment e = (Enrolment)iter.next();
System.out.println("=====================================");
System.out.println(e.getCourse().getName());
System.out.println("=====================================");
}
}
tx.commit();
HibernateUtil.closeSession();
}
Double max = (Double)session.createSQLQuery("select max(cat.weight) as
maxWeight from cats cat")
.addScalar("maxWeight", Hibernate.DOUBLE);
.uniqueResult();
实例名.属性名
//依次将多个选出的字段命名别名,命名别名时都以ss作为前缀,ss是关联实体的别名
String sqlStr = "select stu.studentId as {ss.studentNumber}, "
+ "stu.name as {ss.name} from"
+ "student as stu where stu.name like '张大勇'";
List l = session.createSQLQuery(sqlStr)
//将查询出的ss实例,关联到Student类
.addEntity("ss", Student.class)
.list();
1.命名SQL查询
配置片段:
<!--每个sql-query元素定义一个命名SQL查询-->
<sql-query name="mySQLQuery">
<!--关联返回的结果与实体类-->
<return alias="s" class="Student"/>
<!--定义命名SQL查询的SQL语句-->
SELECT {s.*}
FROM student s WHERE s.name like '张大勇'
</sql-query>
使用该命名SQL查询的示例代码:
private void testNamedSQL() {
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//调用命名查询,直接返回结果
List l = session.getNamedQuery("mySQLQuery").list();
while (it.hasNext())
{
//在定义SQL查询时,已经将结果集与Student类关联起来
//因此,集合里的每个元素都是Student实例
Student s = (Student)it.next();
Set enrolments = s.getEnrolmens();
Iterator iter = enrolments.iterator();
while (iter.hasNext())
{
Enrolment e = (Enrolment)iter.next();
System.out.println("=====================================");
System.out.println(e.getCourse().getName());
System.out.println("=====================================");
}
}
tx.commit();
HibernateUtil.closeSession();
}
2.调用存储过程
Oracle9i存储过程示例:
CREATE OR REPLACE FUNCTION selectAllEmployments
RETURN SYS_REFCURSOR
AS
st_cursor SYS_REFCURSOR;
BEGIN
OPEN st_cursor FOR
SELECT EMPLOYEE, EMPLOYER,
STARTDATE, ENDDATE,
REGIONCODE, EID, VALUE, CURRENCY
FROM EMPLOYMENT;
RETURN st_cursor;
END;
如果需要调用该存储过程,可以先将其定义成命名SQL查询,例如:
<!--定义命名SQL查询,name属性指定命名SQL查询名-->
<sql-query name="selectAllEmployees_SP" callabe="true">
<!--定义返回列与关联实体类属性之间的映射-->
<return alias="emp" class="Employment">
<!--依次定义每列与实体类属性的对应-->
<return-property name="employee" column="EMPLOYEE"/>
<return-property name="employer" column="EMPLOYER"/>
<return-property name="startDate" column="STARTDATE"/>
<return-property name="endDate" column="ENDDATE"/>
<return-property name="regionCode" column="REGIONCODE"/>
<return-property name="id" column="EID"/>
<!--将两列值映射到一个关联类的引用属性-->
<return-property name="salary">
<!--映射列与引用属性之间的关联-->
<return-column name="VALUE"/>
<return-column name="CURRENCY"/>
</retrun-property>
</return>
</sql-query>
$数据过滤
过滤器的使用分三步:
(1)定义过滤器,使用filter-def元素定义过滤器
(2)使用过滤器,使用filter元素使用过滤器
(3)在代码中启用过滤器
请看下面的映射文件示例:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="Category" table="category">
<id name="id" column="category_id">
<generator class="native"/>
</id>
<property name="name" type="string"/>
<property name="effectiveStartDate" column="eff_start_date"
type="java.util.Date"/>
<property name="effectiveEndDate" column="eff_end_date"
type="java.util.Date"/>
<!--映射N-N关联属性-->
<set cascade="none" inverse="true" name="products" table="
product_category>
<!--定义关联属性的key,对应连接表中的外键列-->
<key column="category_id"/>
<!--定义关联属性-->
<many-to-many column="product_id" class="Product"/>
</set>
<!--使用过滤器,并设置过滤条件-->
<filter name="effectiveDate" condition=":asOfDate BETWEEN eff_start
_date and eff_end_date"/>
</class>
<class name="Product" table="product">
<id name="id" column="product_id">
<generator class="native"/>
</id>
<property name="name" type="string"/>
<property name="stockNumber" column="stock_number"
type="int"/>
<property name="effectiveStartDate" column="eff_start_date"
type="java.util.Date"/>
<property name="effectiveEndDate" column="eff_end_date"
type="java.util.Date"/>
<!--映射N-N关联属性-->
<set cascade="all" name="catagories" fetch="join" table="
product_category>
<!--定义关联属性的key,对应连接表中的外键列-->
<key column="product_id"/>
<!--定义关联属性-->
<many-to-many column="category_id" class="Category"
fetch="join">
<!--对关联属性使用第一个过滤器-->
<filter name="effectiveDate"
condition=":asOfDate BETWEEN eff_start_date
and eff_end_date"/>
<!--对关联属性使用第二个过滤器-->
<filter name="category" condition="category_id = : catId"/>
</many-to-many>
</set>
<filter name="effectiveDate"
condition=":asOfDate BETWEEN eff_start_date
and eff_end_date"/>
</class>
<!--定义第一个过滤器,该过滤器包含一个date类型的参数-->
<filter-def name="effectiveDate">
<filter-param name="asOfDate" type="date"/>
</flter-def>
<!--定义第二个过滤器,该过滤器包含一个long类型的参数-->
<filter-def name="category">
<filter-param name="catId" type="long"/>
</flter-def>
</hibernate-mapping>
下面是使用过滤器的示例代码:
private void test() {
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//启用第一个过滤器
session.enableFilter("effectiveDate")
//为过滤器设置参数
.setParameter("asOfDate", new Date());
//启用第二个过滤器
session.enableFilter("categor")
//为过滤器设置参数
.setParameter("catId", new Long(2));
//执行查询,该查询没有任何的查询条件
Iterator results = session.createQuery("form Product as p").iterate();
while (results.hasNext())
{
Product p = (Product)results.next();
System.out.println(p.getName());
//此处获取Product关联的种类,过滤器也将自动应用过滤
Iterator it = p.getCategories().iterator();
System.out.println(p.getCategories().size());
while (it.hasNext())
{
Category c = (Category)it.next();
System.out.println(c.getName());
}
}
tx.commit();
HibernateUtil.closeSession();
}