Hibernate入门

本文介绍了Hibernate ORM框架的基本概念,包括其作为持久层框架的角色和对象关系映射功能。详细讲述了如何在项目中添加Hibernate支持,从配置文件到实体类的创建。还通过测试maven的jar包展示了如何进行 CURD 操作,包括查询、增加、修改和删除数据库记录的流程。

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一、hibernate介绍

    ①、ORM框架/持久层框架    jdbc的一个框架;

     ②、object reference mapping    对象关系映射;

     ③、 通过管理对象来改变数据库中的数据 ,通过管理对象来操作数据库;

优势:跨数据库的无缝移植

二、在项目中添加hibernate支持

  1 添加hibernate相关依赖

  2 在resource目录下添加hibernate.cfg.xml(核心配置文件)

   ① 添加DTD支持

   ② 添加Hibernate的配置

    (1) 数据库相关

(connection.username|connection.password|connection.url|connection.driver_class|dialect)

    (2) 调试相关(show_sql|format_sql)

  3 在开发阶段再创建实体类和实体映射文件(*.hbm.xml) 

     实体必须实现Serializable接口

小结:hibernate.cfg.xml(1)/*.hbm.xml(N)     实体映射文件一定要加到核心配置文件
 

三、测试maven的jar包

①、在pom.xml里面右键鼠标移到Run As会出现很多选项;

②、Maven clear:清除依赖;

③、Maven test:测试是否通过(控制台显示BUILD SUCCESS则表示通过);

四、Hibernate的CURD

1、新建一个maven项目

2、添加hibernate相关依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.DHM</groupId>
  <artifactId>hibernate</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>hibernate Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<maven.compiler.source>1.8</maven.compiler.source>
	<maven.compiler.target>1.8</maven.compiler.target>
	<junit.version>4.12</junit.version>
	<servlet.version>4.0.0</servlet.version>
	<hibernate.version>5.3.0.Final</hibernate.version>
	<mysql.driver.version>8.0.19</mysql.driver.version>
</properties>
  <dependencies>
	<dependency>
		<groupId>junit</groupId>
		<artifactId>junit</artifactId>
		<version>${junit.version}</version>
		<scope>test</scope>
	</dependency>
  <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
	<dependency>
		<groupId>javax.servlet</groupId>
		<artifactId>javax.servlet-api</artifactId>
		<version>${servlet.version}</version>
		<scope>provided</scope>
	</dependency>

	<dependency>
		<groupId>org.hibernate</groupId>
		<artifactId>hibernate-core</artifactId>
		<version>${hibernate.version}</version>
	</dependency>

	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>${mysql.driver.version}</version>
	</dependency>
</dependencies>
  <build>
    <finalName>hibernate</finalName>
    <plugins>
		<plugin>
			<groupId>org.apache.maven.plugins</groupId>
			<artifactId>maven-compiler-plugin</artifactId>
			<version>3.7.0</version>
			<configuration>
				<source>${maven.compiler.source}</source>
				<target>${maven.compiler.target}</target>
				<encoding>${project.build.sourceEncoding}</encoding>
			</configuration>
		</plugin>
	</plugins>
  </build>
</project>

3、在resource目录下添加hibernate.cfg.xml(核心配置文件)

① 引入hibernate-configuration-3.0.dtd约束

 name:类的全限定名
    table:类的对应表
    id标签:
        name:类属性    type:类属性对应的java类型
        column:数据库列段
    priperty标签:
        name:类属性    type:类属性对应的java类型
        column:数据库列段  

<?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-mapping>
<!-- 
    name:类的全限定名
    table:类的对应表
    id标签:
        name:类属性    type:类属性对应的java类型
        column:数据库列段
    priperty标签:
        name:类属性    type:类属性对应的java类型
        column:数据库列段  

 -->
     <class name="com.dhm.entity.User" table="t_hibernate_user">
		<id name="id" type="java.lang.Integer" column="id">
			<generator class="assigned" />
		</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>

②、映射文件

   <!-- 配置映射文件 -->
        <mapping resource="com/dhm/entity/User.hbm.xml" />

<?xml version="1.0" encoding="UTF-8"?>
<!-- 引入dtd约束 -->
<!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5.7 -->
<!-- 		<property name="connection.username">root</property> -->
<!-- 		<property name="connection.password">123456</property> -->
<!-- 		<property name="connection.url">jdbc:mysql://47.100.191.44:3308/lx?useUnicode=true&amp;characterEncoding=UTF-8</property> -->
<!-- 		<property name="connection.driver_class">com.mysql.jdbc.Driver</property> -->
		<!-- 1. 数据库相关8.0 -->
		<property name="connection.username">root</property>
		<property name="connection.password">123456</property>
		<property name="connection.url">jdbc:mysql://127.0.0.1:3306/mybatis_ssm?useUnicode=true&amp;characterEncoding=utf8&amp;serverTimezone=GMT&amp;useSSL=true</property>
		<property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
		<!-- org.hibernate.dialect.MySQLDialect方言 -->
		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
		<!-- <property name="dialect">org.hibernate.dialect.Oracle10gDialect</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>
		<!-- 配置映射文件 -->
		<mapping resource="com/dhm/entity/User.hbm.xml" />
 
		<!-- 主键生成策略 -->
<!-- 		<mapping resource="com/zking/two/entity/Student.hbm.xml" /> -->
<!-- 		<mapping resource="com/zking/two/entity/Worker.hbm.xml" /> -->
 
		<!-- 一对多 -->
<!-- 		<mapping resource="com/zking/four/entity/Order.hbm.xml" /> -->
<!-- 		<mapping resource="com/zking/four/entity/OrderItem.hbm.xml" /> -->
		<!-- 一对多的自关联 -->
<!-- 		<mapping resource="com/zking/five/entity/TreeNode.hbm.xml" /> -->
 
		<!-- 多对多 -->
<!-- 		<mapping resource="com/zking/five/entity/Category.hbm.xml" /> -->
<!-- 		<mapping resource="com/zking/five/entity/Book.hbm.xml" /> -->
     </session-factory>
</hibernate-configuration>

4、CURD

流程:

 1、对框架核心配置文件进行建模
 2、获取sessionFactory工厂
 3、获取session会话
  4、开启事务(查询不需要事务)
  5、session操作对象
  6、提交事务(查询不需要事务)
  7、关闭session

①查询

package com.dhm.test;

import java.util.List;

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

public class QueryDemo {
	public static void main(String[] args) {
		/**
		 * 1、对框架核心配置文件进行建模
		 * 2、获取sessionFactory工厂
		 * 3、获取session会话
		 * 4、开启事务(查询不需要事务)
		 * 5、session操作对象
		 * 6、提交事务(查询不需要事务)
		 * 7、关闭session
		 */
        Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		List list = session.createQuery("from User").list();
		for (Object object : list) {
			System.out.println(object);
			
		}
		session.close();
		
	}

}

结果(控制台):

Hibernate: 
    select
        user0_.id as id1_0_,
        user0_.user_name as user_nam2_0_,
        user0_.user_pwd as user_pwd3_0_,
        user0_.real_name as real_nam4_0_,
        user0_.sex as sex5_0_,
        user0_.birthday as birthday6_0_,
        user0_.create_datetime as create_d7_0_,
        user0_.remark as remark8_0_ 
    from
        t_hibernate_user user0_
User [id=1, userName=rrr, userPwd=999, realName=null, sex=null, birthday=null, createDatetime=null, remark=null]
User [id=2, userName=ls, userPwd=123, realName=李四, sex=男, birthday=2000-11-10, createDatetime=2018-09-29 17:58:13.0, remark=xyz]
User [id=3, userName=zzz2, userPwd=123, realName=null, sex=null, birthday=2018-09-29, createDatetime=2018-09-29 18:07:20.0, remark=null]
User [id=4, userName=zzz2, userPwd=123, realName=null, sex=null, birthday=2018-10-06, createDatetime=2018-10-06 15:17:54.0, remark=null]
User [id=5, userName=bbbb, userPwd=123s, realName=null, sex=null, birthday=null, createDatetime=2018-10-17 00:12:53.0, remark=null]
User [id=6, userName=ttttt, userPwd=6666, realName=null, sex=null, birthday=null, createDatetime=2018-10-17 19:46:20.0, remark=null]
User [id=7, userName=吃吃吃, userPwd=mima, realName=null, sex=null, birthday=null, createDatetime=2018-10-17 23:01:55.0, remark=null]
User [id=9, userName=吃吃吃22, userPwd=mima, realName=null, sex=null, birthday=null, createDatetime=2018-10-17 23:08:45.0, remark=null]
User [id=11, userName=xxx, userPwd=123456, realName=xxx, sex=1, birthday=null, createDatetime=2018-11-17 17:47:03.0, remark=xxx]
User [id=12, userName=xxx, userPwd=123456, realName=xxx, sex=1, birthday=null, createDatetime=2018-11-17 17:48:17.0, remark=xxx]
User [id=13, userName=xxx, userPwd=123456, realName=xxx, sex=1, birthday=2018-11-17, createDatetime=2018-11-17 17:48:48.0, remark=xxx]
User [id=14, userName=精华, userPwd=123456, realName=金燕, sex=女, birthday=null, createDatetime=2018-11-18 17:24:38.0, remark=开小差]
 

主键生成器

generator元素:表示了一个主键生成器,它用来为持久化类实例生成唯一的标识 。

 1、 程序员自己控制:assigned

  2、数据库控制: identity(标识列/自动增长) sequence

  3、 hibernate控制:increment uuid/uuid.hex

  4、 其它:native

②增加

package com.dhm.test;

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;

import com.dhm.entity.User;

public class AddDemo {
	public static void main(String[] args) {
		/**
		 * 1、对框架核心配置文件进行建模
		 * 2、获取sessionFactory工厂
		 * 3、获取session会话
		 * 4、开启事务(查询不需要事务)
		 * 5、session操作对象
		 * 6、提交事务(查询不需要事务)
		 * 7、关闭session
		 */
        Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		User user=new User();
		user.setBirthday(new Date(System.currentTimeMillis()));
		user.setCreateDatetime(new Timestamp(System.currentTimeMillis()));
		user.setId(55);
		user.setRealName("xxd");
		user.setRemark("武侠剧");
		user.setSex("男");
		user.setUserName("四条眉毛");
		user.setUserPwd("123456");
		session.save(user);
		
		transaction.commit();
		session.close();
		
	}
}

结果:

数据库新增一条

 ③修改

package com.dhm.test;

import java.util.List;

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

import com.dhm.entity.User;

public class EditDemo {
	public static void main(String[] args) {
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		User user = session.get(User.class, 55);
		user.setRealName("a带");
		transaction.commit();
		session.close();
		
	
	}

}

结果:

控制台

Hibernate: 
    select
        user0_.id as id1_0_0_,
        user0_.user_name as user_nam2_0_0_,
        user0_.user_pwd as user_pwd3_0_0_,
        user0_.real_name as real_nam4_0_0_,
        user0_.sex as sex5_0_0_,
        user0_.birthday as birthday6_0_0_,
        user0_.create_datetime as create_d7_0_0_,
        user0_.remark as remark8_0_0_ 
    from
        t_hibernate_user user0_ 
    where
        user0_.id=?
Hibernate: 
    update
        t_hibernate_user 
    set
        user_name=?,
        user_pwd=?,
        real_name=?,
        sex=?,
        birthday=?,
        remark=? 
    where
        id=?

数据库

 ④、删除

package com.dhm.test;

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

import com.dhm.entity.User;

public class DelDemo {
	public static void main(String[] args) {
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = configure.buildSessionFactory();
		Session session = sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		User user = session.get(User.class, 55);
		session.delete(user);
		transaction.commit();
		session.close();
		
	}

}

控制台

Hibernate: 
    select
        user0_.id as id1_0_0_,
        user0_.user_name as user_nam2_0_0_,
        user0_.user_pwd as user_pwd3_0_0_,
        user0_.real_name as real_nam4_0_0_,
        user0_.sex as sex5_0_0_,
        user0_.birthday as birthday6_0_0_,
        user0_.create_datetime as create_d7_0_0_,
        user0_.remark as remark8_0_0_ 
    from
        t_hibernate_user user0_ 
    where
        user0_.id=?
Hibernate: 
    delete 
    from
        t_hibernate_user 
    where
        id=?
 

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