Hibernate框架入门

 

简介

　　Hibernate是一个开放源代码的对象关系映射框架，它对JDBC进行了非常轻量级的对象封装，它将POJO与数据库表建立映射关系，是一个全自动的orm框架，hibernate可以自动生成SQL语句，自动执行，使得Java程序员可以随心所欲的使用对象编程思维来操纵数据库。Hibernate可以应用在任何使用JDBC的场合，既可以在Java的客户端程序使用，也可以在Servlet/JSP的Web应用中使用，最具革命意义的是，Hibernate可以在应用EJB的JaveEE架构中取代CMP，完成数据持久化的重任

搭建Hibernate框架

1.创建一个maven项目

创建与数据库相对应的实体类user：

package com.hxc.one.entity;

import java.io.Serializable;
import java.sql.Date;
import java.sql.Timestamp;

public class User implements Serializable{
    
    public User() {
        super();
        // TODO Auto-generated constructor stub
    }
    public User(String userName, String userPwd, String realName, String sex, Date birthday,
            Timestamp createDatetime, String remark) {
        super();
        this.userName = userName;
        this.userPwd = userPwd;
        this.realName = realName;
        this.sex = sex;
        this.birthday = birthday;
        this.createDatetime = createDatetime;
        this.remark = remark;
    }
    private Integer id;
    private String userName;
    private String userPwd;
    private String realName;
    private String sex;
    private Date birthday;
    private Timestamp createDatetime;
    private String remark;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getUserPwd() {
        return userPwd;
    }
    public void setUserPwd(String userPwd) {
        this.userPwd = userPwd;
    }
    public String getRealName() {
        return realName;
    }
    public void setRealName(String realName) {
        this.realName = realName;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public Timestamp getCreateDatetime() {
        return createDatetime;
    }
    public void setCreateDatetime(Timestamp createDatetime) {
        this.createDatetime = createDatetime;
    }
    public String getRemark() {
        return remark;
    }
    public void setRemark(String remark) {
        this.remark = remark;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", userName=" + userName + ", userPwd=" + userPwd + ", realName=" + realName
                + ", sex=" + sex + ", birthday=" + birthday + ", createDatetime=" + createDatetime + ", remark="
                + remark + "]";
    }

}

在实体类的同包路径下，创建与实体类对应的配置文件user.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <!--
        class标签中：
            name：实体类的全路径
            table:实体类对应数据库中的表
        id 标签：
            name：实体类中的属性（映射的是表的主键）
            type：属性类对应的类型
            co'lumn:属性对应的表中的哪一个列段
        property：
            name；实体类中的属性（映射的是表的非主键）
            type：属性对应的类型
            column：属性对应的表中的哪一个列段
            
            1.建模hibernate.cfg.xml 对象，从中拿到了com/hxc/one/entity/user.hbm.xml
            2.建模了user.hbm.xml 拿到了com.hxc.one.entity.User和t_hibernate_user
            3.User user=Class.forName("com.hxc.one.entity.User").newInstance();
                Field userNameField = user.getClass("userName");
                Field userPwdField = user.getClass("userPwd");
                
                select user_name,user_pwd,real_name , ... from t_hibernate_user
                User [id=7, userName=吃吃吃, userPwd=mima, realName=null, sex=null, birthday=null, createDatetime=2018-10-17 15:01:55.0, remark=null]
                User [id=9, userName=吃吃吃22, userPwd=mima, realName=null, sex=null, birthday=null, createDatetime=2018-10-17 15:08:45.0, remark=null]
                userNameField.set(user,吃吃吃)
                userPwdField.set(user,mima)
                ...
                最后user中的所有属性值都有了
            4.循环上一步操作，最终所有user实例都放入了list集合中就是List list
      -->
    <class name="com.hxc.one.entity.User" table="t_hibernate_user">
        <id name="id" type="java.lang.Integer" column="id">
            <generator class="increment" />
        </id>
        <property name="userName" type="java.lang.String" column="user_name">
        </property>
        <property name="userPwd" type="java.lang.String" column="user_pwd">
        </property>
        <property name="realName" type="java.lang.String" column="real_name">
        </property>
        <property name="sex" type="java.lang.String" column="sex">
        </property>
        <property name="birthday" type="java.sql.Date" column="birthday">
        </property>
        <property insert="false" update="false" name="createDatetime"
            type="java.sql.Timestamp" column="create_datetime">
        </property>
        <property name="remark" type="java.lang.String" column="remark">
        </property>
    </class>


</hibernate-mapping>

在Java Resources —>src/main/resources目录下创建hibernate.cfg.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- 1. 数据库相关 -->
        <property name="connection.username">root</property>
        <property name="connection.password">123</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/mytable?useUnicode=true&amp;characterEncoding=UTF-8
        </property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- 配置本地事务（No CurrentSessionContext configured!） -->
        <property name="hibernate.current_session_context_class">thread</property>

        <!-- 2. 调试相关 -->
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>

        <!-- 3. 添加实体映射文件 -->
        <mapping resource="com/hxc/one/entity/user.hbm.xml" />
        
    </session-factory>
</hibernate-configuration>        

hibernate的查询案例

package com.hxc.one.test;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

/**
 * hibernate 中查询案例
 * 
 * @author 旧城
 *
 */
public class QueryDemo {

    public static void main(String[] args) {
        // 对hibernate.cfg.xml进行建模拿到sessionfactory工厂
        Configuration configuration = new Configuration().configure("/hibernate.cfg.xml");
        SessionFactory sessionFactory = configuration.buildSessionFactory();
        // 通过工厂获取到session会话（操作数据库的）
        Session session = sessionFactory.openSession();
        // 直接操作数据库
        List list = session.createQuery("from User").list();
        for (Object object : list) {
            System.out.println(object);
        }
        // 关闭资源
        session.close();
    }
}

效果如下：

hibernate中增加案例

package com.hxc.one.test;

import java.sql.Timestamp;
import java.sql.Date;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import com.hxc.one.entity.User;

/**
 * hibernate中增加案例
 * @author 旧城
 *
 */
public class AddDemo {

    public static void main(String[] args) {
        // 对hibernate.cfg.xml进行建模拿到sessionfactory工厂
        Configuration configuration = new Configuration().configure("/hibernate.cfg.xml");
        SessionFactory sessionFactory = configuration.buildSessionFactory();
        // 通过工厂获取到session会话（操作数据库的）
        Session session = sessionFactory.openSession();
        //获取事务对象
        Transaction transaction=session.beginTransaction();
        // 直接操作数据库
    
        session.save(new User("小李飞刀", "123456", "小李飞刀", "男", new Date(System.currentTimeMillis()),new Timestamp(System.currentTimeMillis()), "天下第一"));
        //显示数据
        List list = session.createQuery("from User").list();
        for (Object object : list) {
            System.out.println(object);
        }
        //提交事务
        transaction.commit();
        // 关闭资源
        session.close();
    }
}

效果如下：

hibernate的修改案例

package com.hxc.one.entity;

import java.sql.Date;
import java.sql.Timestamp;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class EditDemo {
    /**
     * hibernate中修改案例
     * 
     * @author 旧城
     *
     */
    public static void main(String[] args) {
        
            // 对hibernate.cfg.xml进行建模拿到sessionfactory工厂
            Configuration configuration = new Configuration().configure("/hibernate.cfg.xml");
            SessionFactory sessionFactory = configuration.buildSessionFactory();
            // 通过工厂获取到session会话（操作数据库的）
            Session session = sessionFactory.openSession();
            // 获取事务对象
            Transaction transaction = session.beginTransaction();
            // 直接操作数据库

            User user= session.get(User.class, 15);
            System.out.println(user);
            user.setRealName("小李飞刀3");
            
            //显示数据
            List list = session.createQuery("from User").list();
            for (Object object : list) {
                System.out.println(object);
            }
            
            // 提交事务
            transaction.commit();
            // 关闭资源
            session.close();
    }
    
}

 效果如下：

 

hibernate的删除案例

package com.hxc.one.entity;

import java.sql.Date;
import java.sql.Timestamp;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

/**
 * @author 旧城
 *
 */
public class DelDemo {
    public static void main(String[] args) {
        // 对hibernate.cfg.xml进行建模拿到sessionfactory工厂
        Configuration configuration = new Configuration().configure("/hibernate.cfg.xml");
        SessionFactory sessionFactory = configuration.buildSessionFactory();
        // 通过工厂获取到session会话（操作数据库的）
        Session session = sessionFactory.openSession();
        //获取事务对象
        Transaction transaction=session.beginTransaction();
        // 直接操作数据库
        User user=new User();
        user.setId(15);
        session.delete(user);
    
        //显示数据
        List list = session.createQuery("from User").list();
        for (Object object : list) {
            System.out.println(object);
        }
        //提交事务
        transaction.commit();
        // 关闭资源
        session.close();
    }
}

效果如下: