hibernate入门

（可随意切换数据库）

ORM框架/持久层框架        jdbc的一个框架

object reference mapping        对象映射关系

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（无需写数据库，底层生成）

1.新建一个maven项目

2.导入hibernate依赖

  4.0.0
  zw.com
  zw_hibernate
  war
  0.0.1-SNAPSHOT
  zw_hibernate Maven Webapp
  http://maven.apache.org
  
  
	UTF-8
	1.8
	1.8
	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}
	
  
  
    zw_hibernate
    
    
        
                org.apache.maven.plugins
                maven-compiler-plugin
                3.7.0
                
                    1.8
                    1.8
                    UTF-8
                
            
    
    
  

在pom.xml中导jar包依赖时，可能没下载完全，就可以按以下操作检查（可以解决90%jar包没下载完全的问题）：

先清除jar包：

 然年进行测试：

 表示pom文件没有写错 

3.找到框架的配置文件

在resource文件中新建xml文件，取名为hibernate.cfg.xml

 使用外部引用的方法在hibernate.cfg.xml文件中引入dtd约束

    
        




        
        root
        123456
        jdbc:mysql://127.0.0.1:3306/mybatis_ssm?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT&useSSL=true
        com.mysql.cj.jdbc.Driver
        org.hibernate.dialect.MySQLDialect
        

        
        thread

        
        true
        true
        
        

        



        


        


        


    

user类：

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 + "]";
    }

}

还需要写实体类的映射文件及测试代码

        1、对框架核心配置文件（hibernate.cfg.xml）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

查询：

public class QueryDemo {
    public static void main(String[] args) {
        
        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();
    }

}

得到数据：

AddDemo:

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();
        user.setBirthday(new Date(System.currentTimeMillis()));
        user.setCreateDatetime(new Timestamp(System.currentTimeMillis()));
        user.setId(55);
        user.setRealName("小熊");
        user.setRemark("武侠");
        user.setSex("男");
        user.setUserName("yiyi");
        user.setUserPwd("123456");
        session.save(user);
        transaction.commit();
        session.close();
    }

}

修改EditDemo:

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();
//        拿到数据
        User user = session.get(User.class, 55);
//        修改数据
        user.setRealName("toto");
        System.out.println(user);
        
        transaction.commit();
        session.close();
    }

}

删除DelDemo:

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();
//        拿到数据
        User user = session.get(User.class, 55);
//        修改数据
        session.delete(user);
        transaction.commit();
        session.close();
    }