Hibernate入门_增删改查

Posted 2020-08-04

一、Hibernate入门案例剖析：

　　 ①创建实体类Student 并重写toString方法

public class Student {

    private Integer sid;
    private Integer age;
    private String name;
    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "Student [sid=" + sid + ", age=" + age + ", name=" + name + "]";
    }
    
    
}

　　② 创建学生对象 并赋值

 

 　③引入jar包

 

④ 构建大配置<hibernate.cfg.xml>

可分为以下步骤：

1.连接数据库的语句

2.sql方言

3.可省的配置(show_sql、format_sql 取值为true)

4.让程序生成底层数据表(hbm2ddl.auto) update/create。create是每次将数据表删除后，重新创建

5.关联小配置

<mapping resource="cn/happy/entity/Student.hbm.xml" />

关键代码如下：

<?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>

        <!-- Database connection settings 数据库连接设置-->
        <!-- 驱动类 -->
        <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
        <!-- url地址 -->
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl3</property>
        <property name="connection.username">wj</property>
        <property name="connection.password">9090</property>

        <!-- SQL dialect  (SQL 方言) -->
        <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>

        <!--在控制台打印后台的SQL语句 -->
        <property name="show_sql">true</property>
       
        <!-- 格式化显示SQL -->
        <!-- <property name="format_sql">true</property> -->
        <!-- 自动生成student表 -->
         <property name="hbm2ddl.auto">update</property>  
        <!-- 关联小配置 -->
        <mapping resource="cn/happy/entity/Student.hbm.xml" />
        <!-- <mapping class="cn.happy.entity.Grade"/> -->
        
    </session-factory>

</hibernate-configuration>

⑤ 构建小配置(Student.hbm.xml)

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.entity">
        <class name="Student" table="STUDENT">
        <id name="sid" column="SID">
           <!-- 主键生成策略：native:
           native:如果后台是Oracle  
                               后台是mysql，自动应用自增
                               
                               
              assigned:程序员给主键赋值
              uuid:32位的16进制数
              sequence
              native
              
            -->
            
            <generator class="assigned">
               <param name="sequence">SEQ_NUM</param>
            </generator>
        </id>
       <!--  <version name="version"></version> -->
        <property name="name" type="string" column="NAME"/>
        <property name="age"/>
    </class>
</hibernate-mapping>

⑥ 工具类HibernateUtil、构建私有静态的Configuration、SessionFactory对象、定义返回session以及关闭session的方法

private static Configuration cf=new Configuration().configure();
    private static SessionFactory sf=cf.buildSessionFactory();
    
    //方法返回session
    public static Session getSession(){
        return sf.openSession();
    }
    
    //关闭Session
    
    public static void CloseSession(){
        getSession().close();
    }
复制代码

⑦测试类【增删改查】 使用标记After、Before可简化代码

package cn.happy.test;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import cn.happy.entity.Student;
import cn.happy.util.HibernateUtil;

public class Test1 { 
    Session session;
    Transaction tx; 

    @After
    public void afterTest(){
        tx.commit();
        HibernateUtil.CloseSession();
    }

    @Before
    public void initData(){
        session=HibernateUtil.getSession();
        tx=session.beginTransaction();
    }
    
    /*
     * get方法查询
     */
    @Test
    public void getData(){
        Student stu=(Student)session.get(Student.class, 3);
        System.out.println(stu);
    }
    /*
     * 增加
     */
    
    @Test
    public void addData(){
        Student stu=new Student();
        stu.setSid(12);
        stu.setAge(11);
        stu.setName("李小龙1");
    //读取大配置文件 获取连接信息
        Configuration cfg=new Configuration().configure();
    
    //创建SessionFactory
        SessionFactory fa=cfg.buildSessionFactory();
    //加工Session
    Session se=fa.openSession();
    Transaction tx = se.beginTransaction();
    //保存
    se.save(stu);
    //事务提交
    tx.commit();
    se.close();
    
    System.out.println("Save ok!");
    }
     
    /*
     * 删除
     */
    @Test
    public void delData(){
        Session session=HibernateUtil.getSession();
        Student stu=new Student();
        stu.setSid(2);
        Transaction tx=session.beginTransaction();
        session.delete(stu);
        tx.commit();
        HibernateUtil.CloseSession();
        System.out.println("del ok!");
    }
    
    /*
     * 修改
     */
    @Test
    public void updateData(){
        Session session=HibernateUtil.getSession();        
        Student stu=(Student)session.load(Student.class,3);
        stu.setName("呵呵");
        Transaction tx=session.beginTransaction();
        session.update(stu);
        tx.commit();
        HibernateUtil.CloseSession();
        System.out.println("update ok!");
    }
    }