HQL和Criteria
HQL(Hibernate Query Language)
面向对象的查询语言，与SQL不同，HQL中的对象名是区分大小写的（除了JAVA类和属性其他部分不区分大小写）；HQL中查的是对象而不是和表，并且支持多态；HQL主要通过Query来操作，Query的创建方式：
Query q = session.createQuery(hql);
from Person
from User user where user.name=:name
from User user where user.name=:name and user.birthday < :birthday
示例代码：
public static void query(String name){
Session s=null;
try{
s=HibernateUntils.getSession();
String hql="from User as user where user.username=?";//from Object,查找的是对象
Query query=s.createQuery(hql);
query.setString(0, name);
List<User> list=query.list();
for(User user:list){
System.out.println(user.getBirthday());
}
}finally{
if(s!=null){
s.close();
}
}
}
/**
* 确定查询结果只有一条时
* @param name
*/
public static void uniqueQuery(String name){
Session s=null;
try{
s=HibernateUntils.getSession();
String hql="from User as user where user.username=?";//from Object,查找的是对象
Query query=s.createQuery(hql);
query.setString(0, name);
User u=(User) query.uniqueResult();
System.out.println(u.getBirthday());
}finally{
if(s!=null){
s.close();
}
}
}
/**
* 分页查询
* @param name
*/
public static void queryPage(String name){
Session s=null;
try{
s=HibernateUntils.getSession();
String hql="from User as user where user.username=:name";//from Object,查找的是对象
Query query=s.createQuery(hql);
query.setString("name", name);
query.setFirstResult(0);//第一条记录从哪一条开始去
query.setMaxResults(10);//取多少条
List<User> list=query.list();
for(User user:list){
System.out.println(user.getBirthday());
}
}finally{
if(s!=null){
s.close();
}
}
}
Criteria
Criteria是一种比HQL更面向对象的查询方式；Criteria的创建方式：
Criteria crit = session.createCriteria(DomainClass.class);
简单属性条件如：criteria.add(Restrictions.eq(propertyName, value)),
criteria.add(Restrictions.eqProperty(propertyName,otherPropertyName))
/**
* 条件查询
* @param name
*/
public static void cri(String name){
Session s=null;
try{
s=HibernateUntils.getSession();
Criteria c=s.createCriteria(User.class);
c.add(Restrictions.eq("username", name));//加入约束条件
List<User> list=c.list();
for(User user:list){
System.out.println(user.getBirthday());
}
}finally{
if(s!=null){
s.close();
}
}
}
小练习：
实验步骤：
1.设计domain对象User。
2.设计UserDao接口。
3.加入hibernate.jar和其依赖的包。
4.编写User.hbm.xml映射文件，可以基于hibernate/eg目录下的org/hibernate/auction/User.hbm.xml修改。
5.编写hibernate.cfg.xml配置文件，可以基于hibernate/etc/hibernate.cfg.xml修改；必须提供的几个参数：
connection.driver_class、connection.url、connection.username、connection.password、dialect、hbm2ddl.auto。
6.编写HibernateUtils类，主要用来完成Hibnerate初始化和提供一个获得Session的方法；这步可选。
7.实现UserDao接口。
源代码：
User.java 实体类
package com.dzq.domain; import java.io.Serializable;
import java.util.Date; public class User implements Serializable{
private int id;
private String username;
private String password;
private String mobile;
private Date regdate; public int getId() {
return id;
} public void setId(int id) {
this.id = id;
} public String getUsername() {
return username;
} public void setUsername(String username) {
this.username = username;
} public String getPassword() {
return password;
} public void setPassword(String password) {
this.password = password;
} public String getMobile() {
return mobile;
} public void setMobile(String mobile) {
this.mobile = mobile;
} public Date getRegdate() {
return regdate;
} public void setRegdate(Date regdate) {
this.regdate = regdate;
} }
UserDao.java 接口
package com.dzq.dao;
import com.dzq.domain.User;
public interface UserDao {
/**
* 添加用户
*
* @param user
*/
void addUser(User user);
/**
* 修改用户
*
* @param user
*/
void updateUser(User user);
/**
* 删除用户
*
* @param user
*/
void deleteUser(User user);
/**
* 根据id查找用户
*
* @param id
*/
User findUserByID(int id);
/**
* 根据id删除用户
*
* @param id
*/
void deleteUserByID(int id);
/**
* 根据用户名查找用户
* @param username
*/
User findUserByUN(String username);
}
User.hbm.xml 实体配置
<?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 package="com.dzq.domain"> <class name="User" table="user">
<id name="id" column="id">
<generator class="native" />
</id>
<property name="username" column="username" />
<property name="password" column="password" />
<property name="mobile" column="mobile" />
<property name="regdate" column="regdate"/>
</class> </hibernate-mapping>
hibernate.cfg.xml 全局配置文件
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql:///test1</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password"></property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.show_sql">true</property>
<mapping resource="com/dzq/domain/User.hbm.xml"/>
</session-factory> </hibernate-configuration>
HibernateUtils.java 工具类
package com.dzq.utils; import java.io.Serializable; import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration; public class HibernateUntils {
private static SessionFactory sessionFactory; private HibernateUntils() { } static {
Configuration cfg = new Configuration();
cfg.configure();//如果不是hibernate.cfg.xml这个文件名，需要加上文件名
sessionFactory = cfg.buildSessionFactory();
}
public static SessionFactory getSessionFactory(){
return sessionFactory;
}
public static Session getSession(){
return sessionFactory.openSession();
} /**
* 添加
* @param entity
*/
public static void add(Object entity) {
Session s = null;
Transaction tx = null;
try {
s = HibernateUntils.getSession();
tx = s.beginTransaction();
s.save(entity);
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
throw new RuntimeException(e);
} finally {
if (s != null) {
s.close();
}
}
}
/**
* 修改
* @param entity
*/
public static void update(Object entity) {
Session s = null;
Transaction tx = null;
try {
s = HibernateUntils.getSession();
tx = s.beginTransaction();
s.update(entity);
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
throw new RuntimeException(e);
} finally {
if (s != null) {
s.close();
}
}
} /**
* 删除
* @param entity
*/
public static void delete(Object entity) {
Session s = null;
Transaction tx = null;
try {
s = HibernateUntils.getSession();
tx = s.beginTransaction();
s.delete(entity);
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
throw new RuntimeException(e);
} finally {
if (s != null) {
s.close();
}
}
} /**
* 根据主键id查询
* @param clazz
* @param id
* @return
*/
public static Object get(Class clazz,Serializable id) {
Session s = null;
try {
s = HibernateUntils.getSession();
Object obj=s.get(clazz, id);
return obj;
} finally {
if (s != null) {
s.close();
}
}
}
}
UserDaoImpl.java 接口实现
package com.dzq.dao.impl; import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction; import com.dzq.dao.UserDao;
import com.dzq.domain.User;
import com.dzq.utils.HibernateUntils; public class UserDaoImpl implements UserDao { @Override
public void addUser(User user) {
HibernateUntils.add(user);
} @Override
public void updateUser(User user) {
HibernateUntils.update(user);
} @Override
public void deleteUser(User user) {
HibernateUntils.delete(user);
} @Override
public User findUserByID(int id) {
return (User) HibernateUntils.get(User.class, id);
} @Override
public void deleteUserByID(int id) {
Session s = null;
Transaction tx = null;
try {
s = HibernateUntils.getSession();
tx = s.beginTransaction();
String hql="delete User user where user.id=:id";
Query query=s.createQuery(hql);
query.setInteger("id", id);
query.executeUpdate();
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
throw new RuntimeException(e);
} finally {
if (s != null) {
s.close();
}
}
} @Override
public User findUserByUN(String username) {
Session s=null;
try{
s=HibernateUntils.getSession();
String hql="from User as user where user.username=:username";//from Object,查找的是对象
Query query=s.createQuery(hql);
query.setString("username", username);
User user=(User) query.uniqueResult();
return user;
}finally{
if(s!=null){
s.close();
}
}
} }
ProjectTest.java 下面为junit测试
package com.dzq.test; import java.util.Date; import org.junit.Test; import com.dzq.dao.impl.UserDaoImpl;
import com.dzq.domain.User; public class ProjectTest {
@Test
public void testAdd() {
UserDaoImpl dao = new UserDaoImpl();
User user = new User();
user.setUsername("xiaodu");
user.setPassword("hello");
user.setRegdate(new Date());
user.setMobile("15820090820");
dao.addUser(user);
} @Test
public void testUpdate() {
UserDaoImpl dao = new UserDaoImpl();
User user = new User();
user = dao.findUserByID(2);
user.setUsername("xiaohong");
dao.updateUser(user);
} @Test
public void testDelete(){
UserDaoImpl dao = new UserDaoImpl();
User user = new User();
user = dao.findUserByID(3);
dao.deleteUser(user);
}
@Test
public void testFindUser(){
UserDaoImpl dao = new UserDaoImpl();
User user = new User();
user=dao.findUserByUN("xiaohong");
System.out.println(user.getRegdate());
}
@Test
public void testDeleteByID(){
UserDaoImpl dao = new UserDaoImpl();
dao.deleteUserByID(2);
} }