目录

一、概念

二、主键生成策略

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

三、使用

①在pom.xml中导入Hibernate相关依赖

②配置hibernate.cfg.xml文件

③创建实体类，配置映射文件

④测试

一、概念

Hibernate是持久层的ORM框架，我们可以通过操作java对象来操作我们的数据库数据。

什么是ORM？

Object Relation Mapping（对象关系映射），利用XML文件建立实体类和数据库表之间建立一种映

射关系，实现操作对象控制数据！提高开发人员访问数据层的编程效率。

二、主键生成策略

通过操作对象来控制数据，那么在该表中添加数据它的ID（主键）怎么控制呢？

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

在实体类与表建立映射关系的XML配置文件中设置！

三、使用

①在pom.xml中导入Hibernate相关依赖

  4.0.0
  com.zwf
  Maven_hib
  war
  0.0.1-SNAPSHOT
  Maven_hib Maven Webapp
  http://maven.apache.org
  
		4.12
		4.0.0
		5.3.0.Final
		8.0.19
	
 
	
		
			junit
			junit
			${junit.version}
			test
		
 
		
			javax.servlet
			javax.servlet-api
			${servlet.version}
			provided
		
 
		
			org.hibernate
			hibernate-core
			${hibernate.version}
		
 
		
			mysql
			mysql-connector-java
			${mysql.driver.version}
		
	
  
    Maven_hib
  

②配置hibernate.cfg.xml文件

	
		




		root
		root123
		jdbc:mysql://127.0.0.1:3306/zwf?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT&useSSL=true
		com.mysql.cj.jdbc.Driver
		org.hibernate.dialect.MySQLDialect
		
 
		
		thread
 
		
		true
		true
		
		
 
		


 
		


		

 
		


	

③创建实体类，配置映射文件

name和实体类属性名对应，column和数据库列名对应！！！

实体类：User.java

package com.zwf.po;
 
import java.sql.Date;
import java.sql.Timestamp;
 
public class User {
	private int id;
	private String userName;
	private String userPwd;
	private String realName;
	private String sex;
	private Date birthday;
	private Timestamp createDatetime;
	private String remark;
	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 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 + "]";
	}
	
	
	
}

④测试

1、增加

    //1.对框架核心配置文件进行建模
	Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
	//2.获取sessionFactory工厂
	SessionFactory buildSessionFactory = configure.buildSessionFactory();
	//3.获取session会话
	Session openSession = buildSessionFactory.openSession();
	//4.开启事务
	Transaction beginTransaction = openSession.beginTransaction();
	//5.session 操作对象
	User user=new User();
	user.setId(18);
	user.setBirthday(new Date(System.currentTimeMillis()));
	user.setUserName("张三");
	openSession.save(user);
	// 6.提交事务
	beginTransaction.commit();
	//7.关闭session
	openSession.close();

2、删除

	    //1.对框架核心配置文件进行建模
		Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
		//2.获取sessionFactory工厂
		SessionFactory buildSessionFactory = configure.buildSessionFactory();
		//3.获取session会话
		Session openSession = buildSessionFactory.openSession();
		//4.开启事务
		Transaction beginTransaction = openSession.beginTransaction();
		//5.session 操作对象
        //方式一
		User user = openSession.get(User.class, 12);//查找对应数据
		openSession.delete(user);
        //方式二
        //User user = new User();
        //user.setId(12);
        //openSession.delete(user);
		// 6.提交事务
		beginTransaction.commit();
		//7.关闭session
		openSession.close();

通过我们传入的对象（具备id属性）删除对应数据

3、修改

    //1.对框架核心配置文件进行建模
	Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
	//2.获取sessionFactory工厂
	SessionFactory buildSessionFactory = configure.buildSessionFactory();
	//3.获取session会话
	Session openSession = buildSessionFactory.openSession();
	//4.开启事务
	Transaction beginTransaction = openSession.beginTransaction();
	//5.session 操作对象
	User user = openSession.get(User.class, 14);
	user.setUserName("cc");//修改name
	openSession.update(user);
	// 6.提交事务
	beginTransaction.commit();
	//7.关闭session
	openSession.close();

获得要修改的对象，然后修改属性提交事务完成对数据的修改！

4、查询（不需要事务）

            //1.对框架核心配置文件进行建模
			Configuration configure = new Configuration().configure("/hibernate.cfg.xml");
			//2.获取sessionFactory工厂
			SessionFactory buildSessionFactory = configure.buildSessionFactory();
			 //3.获取session会话
			Session openSession = buildSessionFactory.openSession();
			//4.session 操作对象
			List list = openSession.createQuery("  from User  ").list();
			for (Object object : list) {
				System.out.println(object);
			}
			//7.关闭session
			openSession.close();