Criteria:代表一次查詢
Criterion:代表一個查詢條件
Restrictions:產生查詢條件的工具類
執行條件查詢的步驟如下:
(1)獲得Hibernate的Session對象
(2)以Session對象創建Criteria對象
(3)增加Criterion查詢條件
(4)執行Criteria的list等方法返回結果集
請看示例:
private void test()
{
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//創建Criteria和添加查詢條件同步完成
//最後調用list方法,返回查詢到的結果集
List l = session.createCriteria(Student.class)
//此處增加到限制條件必須是Student已經存在的屬性
.add(Restritions.gt("studentNumber", new Long(20071127)))
//如果要增加對Student關聯類的屬性限制,則必須重新創建
//如果此關聯屬性是集合,則只要集合裏任意一個對象的屬性滿足下麪條件即可
.createCriteria("enrolments")
.add(Restritions.gt("semester", new Short("2")))
.list();
Iterator it = l.iterator();
//遍歷查詢到的記錄
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多了兩個重載的構造方法
addEntity:將查詢到的記錄與特定的實體關聯
addScalar:將查詢到的記錄關聯成標量值
執行SQL查詢的步驟如下:
(1)獲取Hibernate Session對象
(2)編寫SQL語句
(3)以SQL語句作爲參數,調用Session的createSQLQuery方法創建查詢對象
(4)如果SQL語句包含參數,則調用Query的setXxx方法爲參數賦值
(5)調用SQLQuery對象的addEntiy或addScalar方法,將選出的結果與實體或標量值關聯
(6)調用Query的list方法返回查詢的結果集
請看SQL的查詢示例:
private void test() {
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//編寫SQL語句
String sqlString = "select {s.*} from student s where s.name like '李四'";
//以SQL語句創建SQLQuery對象
List l = session.createSQLQuery(sqlString)
//將查詢到的記錄與特定實體關聯起來
.addEntity("s", Student.class)
//返回全部的記錄集
.list();
Iterator it = l.iterator();
while (it.hasNext())
{
//因爲將查詢的結果與Student類關聯,因此返回時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();
實例名.屬性名
//依次將多個選出的字段命名別名,命名別名時都以ss作爲前綴,ss是關聯實體的別名
String sqlStr = "select stu.studentId as {ss.studentNumber}, "
+ "stu.name as {ss.name} from"
+ "student as stu where stu.name like '張大勇'";
List l = session.createSQLQuery(sqlStr)
//將查詢出的ss實例,關聯到Student類
.addEntity("ss", Student.class)
.list();
1.命名SQL查詢
配置片段:
<!--每個sql-query元素定義一個命名SQL查詢-->
<sql-query name="mySQLQuery">
<!--關聯返回的結果與實體類-->
<return alias="s" class="Student"/>
<!--定義命名SQL查詢的SQL語句-->
SELECT {s.*}
FROM student s WHERE s.name like '張大勇'
</sql-query>
使用該命名SQL查詢的示例代碼:
private void testNamedSQL() {
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//調用命名查詢,直接返回結果
List l = session.getNamedQuery("mySQLQuery").list();
while (it.hasNext())
{
//在定義SQL查詢時,已經將結果集與Student類關聯起來
//因此,集合裏的每個元素都是Student實例
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.調用存儲過程
Oracle9i存儲過程示例:
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;
如果需要調用該存儲過程,可以先將其定義成命名SQL查詢,例如:
<!--定義命名SQL查詢,name屬性指定命名SQL查詢名-->
<sql-query name="selectAllEmployees_SP" callabe="true">
<!--定義返回列與關聯實體類屬性之間的映射-->
<return alias="emp" class="Employment">
<!--依次定義每列與實體類屬性的對應-->
<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"/>
<!--將兩列值映射到一個關聯類的引用屬性-->
<return-property name="salary">
<!--映射列與引用屬性之間的關聯-->
<return-column name="VALUE"/>
<return-column name="CURRENCY"/>
</retrun-property>
</return>
</sql-query>
$數據過濾
過濾器的使用分三步:
(1)定義過濾器,使用filter-def元素定義過濾器
(2)使用過濾器,使用filter元素使用過濾器
(3)在代碼中啓用過濾器
請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關聯屬性-->
<set cascade="none" inverse="true" name="products" table="
product_category>
<!--定義關聯屬性的key,對應連接表中的外鍵列-->
<key column="category_id"/>
<!--定義關聯屬性-->
<many-to-many column="product_id" class="Product"/>
</set>
<!--使用過濾器,並設置過濾條件-->
<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關聯屬性-->
<set cascade="all" name="catagories" fetch="join" table="
product_category>
<!--定義關聯屬性的key,對應連接表中的外鍵列-->
<key column="product_id"/>
<!--定義關聯屬性-->
<many-to-many column="category_id" class="Category"
fetch="join">
<!--對關聯屬性使用第一個過濾器-->
<filter name="effectiveDate"
condition=":asOfDate BETWEEN eff_start_date
and eff_end_date"/>
<!--對關聯屬性使用第二個過濾器-->
<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>
<!--定義第一個過濾器,該過濾器包含一個date類型的參數-->
<filter-def name="effectiveDate">
<filter-param name="asOfDate" type="date"/>
</flter-def>
<!--定義第二個過濾器,該過濾器包含一個long類型的參數-->
<filter-def name="category">
<filter-param name="catId" type="long"/>
</flter-def>
</hibernate-mapping>
下面是使用過濾器的示例代碼:
private void test() {
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
//啓用第一個過濾器
session.enableFilter("effectiveDate")
//爲過濾器設置參數
.setParameter("asOfDate", new Date());
//啓用第二個過濾器
session.enableFilter("categor")
//爲過濾器設置參數
.setParameter("catId", new Long(2));
//執行查詢,該查詢沒有任何的查詢條件
Iterator results = session.createQuery("form Product as p").iterate();
while (results.hasNext())
{
Product p = (Product)results.next();
System.out.println(p.getName());
//此處獲取Product關聯的種類,過濾器也將自動應用過濾
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();
}