打开Hibernate的Session的源码，我们可以看到有一个getNamedQuery(String name);的方法，如下：

/*** Obtain an instance of <tt>Query</tt> for a named query string defined in the* mapping file.** @param queryName the name of a query defined externally* @return Query* @throws HibernateException*/public Query getNamedQuery(String queryName) throws HibernateException;

这个方法就是可以执行定义在Hibernate实体类映射文件中的HQL或Sql语句。

具体做法下面我一一讲解，首先测试在映射文件中定义HQL语句。

我在User实体类的映射文件中定义了一个name为getUserByName的HQL查询语句，代码如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""D:\tools\hibernate\dtd\hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.xigua.domain"><class name="User"><id name="id"><generator class="native"/></id><property name="name"/><property name="birthday"/></class><!-- 定义一个查询，名称为getUserByName --><query name="getUserByName"><![CDATA[from User where name = :name]]></query>
</hibernate-mapping>

然后编写测试类使用Session中的getNamedQuery(String name)方法进行测试，代码如下：

package com.xigua.test;import java.util.Date;
import java.util.List;import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;import com.xigua.domain.User;
import com.xigua.utils.HibernateUtil;public class Test9 {public static void main(String[] args) {addUser();String name = "xigua";List<User> list = namedQuery(name);if(list != null && !list.isEmpty()) {for(User user : list) {System.out.println(user.getId() + ", " + user.getName() + ", " + user.getBirthday());}}}public static void addUser() {Session session = null;Transaction tx = null;try{session = HibernateUtil.getSession();tx = session.beginTransaction();User user = new User();user.setName("xigua");user.setBirthday(new Date());session.save(user);user = new User();user.setName("donggua");user.setBirthday(new Date());session.save(user);tx.commit();} catch(Exception e) {if(tx != null) {tx.rollback();}} finally {if(session != null) {session.close();}}}public static List<User> namedQuery(String name) {Session session = null;try{session = HibernateUtil.getSession();Query query = session.getNamedQuery("getUserByName");query.setParameter("name", name);return query.list();}catch(Exception e) {e.printStackTrace();} finally {if(session != null) {session.close();}}return null;}}

注意红色部分代码。

在映射文件中除了可以定义HQL语句，也还是可以定义Sql语句的。

前面的User实体类的映射文件修改如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""D:\tools\hibernate\dtd\hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.xigua.domain"><class name="User"><id name="id"><generator class="native"/></id><property name="name"/><property name="birthday"/></class><!-- 定义一个查询，名称为getUserByName <query name="getUserByName"><![CDATA[from User where name = :name]]></query>--><sql-query name="getUserByName"><![CDATA[select id, name from user where name = :name]]></sql-query>
</hibernate-mapping>

测试代码如下：

package com.xigua.test;import java.util.Date;import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;import com.xigua.domain.User;
import com.xigua.utils.HibernateUtil;public class Test10 {public static void main(String args[]) {addUser();String name = "xigua";User user = namedSqlQuery(name);if(user != null) {System.out.println(user.getId() + ", " + user.getName());}}public static void addUser() {Session session = null;Transaction tx = null;try{session = HibernateUtil.getSession();tx = session.beginTransaction();User user = new User();user.setName("xigua");user.setBirthday(new Date());session.save(user);user = new User();user.setName("donggua");user.setBirthday(new Date());session.save(user);tx.commit();} catch(Exception e) {if(tx != null) {tx.rollback();}} finally {if(session != null) {session.close();}}}public static User namedSqlQuery(String name) {Session session = null;try{session = HibernateUtil.getSession();Query query = session.getNamedQuery("getUserByName");query.setParameter("name", name);Object[] obj = (Object[]) query.uniqueResult();if(obj != null) {User user = new User();user.setId(Long.valueOf(obj[0].toString()));user.setName(obj[1].toString());return user;}}catch(Exception e) {e.printStackTrace();} finally {if(session != null) {session.close();}}return null;}}

映射文件中还有些其它的配置，暂时还没具体搞懂，比如下面红色的代码：

<sql-query name="getUserByName"><![CDATA[select id, name from user where name = :name]]><query-param name="name" type="string"/><return></return><return-join alias="" property=""></return-join><return-scalar column=""/><synchronize table=""/></sql-query>

还有一点像说明的是<query>跟<sql-query>的配置是可以放到<class>节点里面的。

我现在是放在<class>节点外面，表示全局可用，这里需要注意不要跟其它映射文件中定义的<query>或<sql-query>同名。

如果将<query>或<sql-query>放在<class>节点里面，在java代码中使用的时候需要将package名跟class名都写上，具体见下面配置的映射文件代码跟测试代码。

映射文件代码：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""D:\tools\hibernate\dtd\hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.xigua.domain"><class name="User"><id name="id"><generator class="native"/></id><property name="name"/><property name="birthday"/><!-- 定义一个查询，名称为getUserByName (这里将<query>放到<class>节点里面来)--> <query name="getUserByName"><![CDATA[from User where name = :name]]></query></class></hibernate-mapping>

java测试代码（注意下图红色部分字符串）

package com.xigua.test;import java.util.Date;
import java.util.List;import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;import com.xigua.domain.User;
import com.xigua.utils.HibernateUtil;public class Test9 {public static void main(String[] args) {addUser();String name = "xigua";List<User> list = namedQuery(name);if(list != null && !list.isEmpty()) {for(User user : list) {System.out.println(user.getId() + ", " + user.getName() + ", " + user.getBirthday());}}}public static void addUser() {Session session = null;Transaction tx = null;try{session = HibernateUtil.getSession();tx = session.beginTransaction();User user = new User();user.setName("xigua");user.setBirthday(new Date());session.save(user);user = new User();user.setName("donggua");user.setBirthday(new Date());session.save(user);tx.commit();} catch(Exception e) {if(tx != null) {tx.rollback();}} finally {if(session != null) {session.close();}}}public static List<User> namedQuery(String name) {Session session = null;try{session = HibernateUtil.getSession();Query query = session.getNamedQuery("com.xigua.domain.User.getUserByName");query.setParameter("name", name);return query.list();}catch(Exception e) {e.printStackTrace();} finally {if(session != null) {session.close();}}return null;}}