hibernate入门

1. 什么是hibernate

ORM框架/持久层框架 jdbc的一个框架
object reference mapping
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

注1：Object Relational Mapping
1、加载驱动
2、建立连接
3、获取预定义处理对象 preparestatment
4、执行sql
5、处理结果集
6、关闭

2. 如何在项目中添加hibernate支持(手动添加)
   2.1 添加hibernate相关依赖
   2.2 在resource目录下添加hibernate.cfg.xml(核心配置文件)
   2.2.1 添加DTD支持
   2.2.2 添加Hibernate的配置
   2.2.2.1 数据库相关
   2.2.2.2 调试相关(show_sql|format_sql)

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

2.3 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

3. hibernate核心API讲解
   3.1 Configuration
   读取hibernate.cfg.xml
   3.2 SessionFactory(1)
   3.3 Session(N)
   注1：
   注2：
   3.3.1 save
   3.3.2 get
   load
   3.3.3 delete(先查再删除,保证程序的健壮性)
   User u = (User) session.get(User.class,99);
   if(null!=u){
   session.delete(u);//比如id=99不存在,直接删除就会报错
   }
   3.3.4 update
   先查再改

   局部修改

   3.3.4 createQuery

3.4 Transaction(自动事务和手动事务讲解)
commit/rollback

3.5 Query(hql一章讲)
查全部/批量修改或删除
list setXxx(String name,Xxx value); setParameter(String name, Object value) setParameterList(String name, Collection values) setParameterList(String name, Object[] values) setFirstResult/setMaxResults

4. 如何使用hibernate完成CRUD操作
   4.1 CRUD操作步骤
   4.1.1 读取配置
   4.1.2 创建SessionFactory
   4.1.3 打开Session
   4.1.4 开启事务
   4.1.5 CURD
   4.1.6 提交事务/回滚事务
   4.1.7 关闭Session
   4.2 注意事项
   4.2.1 hibernate默认使用的是手动事务，因此必须显示的开启和提交事务
   4.2.2 删除操作时，必须先查再删

5. 工具类SessionFactoryUtil

6. OID属性
   与数据库主键列映射的属性

---

hibernate/pom.xml

<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.lrc</groupId>
   <artifactId>hibernate</artifactId>
   <packaging>war</packaging>
   <version>0.0.1-SNAPSHOT</version>
   <name>lrc_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>5.1.46</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>${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>

User

---

package com.lrc.a.entity;

import java.sql.Date;
import java.sql.Timestamp;

public class User {
	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 + "]";
	}

	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;
	}

	public User() {
		super();
	}

}

hibernate.cfg.xml

<?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://127.0.0.1:3306/sys?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/lrc/a/entity/User.hbm.xml" />
	</session-factory>
</hibernate-configuration>

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标签下的属性
			name:指的是数据库中的表所映射的类的全路径名
			table：要映射的数据库表
		
		id标签：是用来表示主键的映射列
			name：数据库表的列段映射到实体类中的属性名
			type：属性名的类型
			column：数据库中的列段
			
		property标签：
			name：数据库表的列段映射到实体类中的属性名
			type：属性名的类型
			column：数据库中的列段
	 -->
	<class name="com.lrc.a.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>

AddDemo

---

package com.lrc.a.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.lrc.a.entity.User;

/**
 * 演示hibernate新增
 * 
 * @author Administrator
 *
 */
public class AddDemo {
	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 = new User("zs", "123", "张三", "人妖", new Date(System.currentTimeMillis()), new Timestamp(System.currentTimeMillis()), "玩玩而已，不必当真");
		session.save(user);
		
		transaction.commit();
		session.close();
	}
}

DelDemo

---

package com.lrc.a.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.lrc.a.entity.User;

/**
 * 演示hibernate删除
 * 
 * @author Administrator
 *
 */
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 = new User();
		user.setId(15);
		session.delete(user);
		
		transaction.commit();
		session.close();
	}
}

EditDemo

---

package com.lrc.a.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.lrc.a.entity.User;

/**
 * 演示hibernate修改
 * 
 * @author Administrator
 *
 */
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 = new User("ww", "12345", "王五", "人妖", new Date(System.currentTimeMillis()), new Timestamp(System.currentTimeMillis()), "换一个玩玩");
//		user.setId(15);
//		session.update(user);
		User user = session.get(User.class, 15);
		user.setRealName("吴亦凡");
		System.out.println(user);
		
		transaction.commit();
		session.close();
	}
}

QueryDemo

---

package com.lrc.a.test;

import java.util.List;

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

/**
 * 演示hibernate查询
 * 
 * @author Administrator
 *
 */
public class QueryDemo {
	public static void main(String[] args) {
		/*
		 * 1、对hibernate.cfg.xml这个核心的配置文件进行建模
		 * 2、建模后的对象configure去获取sessionfactory对象，sessionfactory对象中包含了数据库相关信息
		 * 3、通过sessionfactory对象去获取session会话
		 * 4、session开启事务（查询中是不需要）
		 * 5、操作数据库
		 * 6、提交事务（查询中是不需要）
		 * 7、释放资源
		 */
		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 obj : list) {
			System.out.println(obj);
		}
		
		session.close();
	}
}

---