20160506-hibernate入门

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);
	}

}