Hibernate学习2—Hibernate4 CRUD体验初步

接着上一节，工程结构：

jar包没有变化；

一、HibernateUtil 封装：　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

com.cy.util.HibernateUtil.java:

package com.cy.util;

import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {

    private static final SessionFactory sessionFactory = buildSessionFactory();

    private static SessionFactory buildSessionFactory(){
        Configuration configuration = new Configuration().configure();    //实例化配置文件,默认指定的就是hibernate.cfg.xml
        StandardServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();//实例化服务登记,服务注册
        return configuration.buildSessionFactory(serviceRegistry);    //获取session工厂
    }

    //获取sessionFactory，是单例的
    public static SessionFactory getSessionFactory(){
        return sessionFactory;
    }
}

二、XML 版CRUD 实现：　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

对Student类进行xml配置，crud操作；

com.cy.model.student.java:

package com.cy.model;

public class Student {
    private long id;
    private String name;

    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + "]";
    }

}

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="com.cy.model">
    <class name="Student" table="t_student">
        <!--
            <id>代表主键
            类的属性名是id，对应表中列名是stuId
         -->
        <id name="id" column="stuId">
            <!-- 主键生成策略，这里采用mysql的native，自增 -->
            <generator class="native"></generator>
        </id>

        <!-- 普通属性采用property
             不写column，那么数据库table的列名也叫name
        -->
        <property name="name"></property>

    </class>

</hibernate-mapping>

com.cy.service.StudentTest.java:--这里是测试类，对Student进行CRUD：

package com.cy.service;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;

import com.cy.model.Student;
import com.cy.util.HibernateUtil;

public class StudentTest {

    private static SessionFactory sessionFactory = HibernateUtil.getSessionFactory();

    //添加学生
    private void add(){
        Session session = sessionFactory.openSession();    //生成一个session
        session.beginTransaction();        //开启事务

        Student s = new Student();
        s.setName("张三");
        session.save(s);

        session.getTransaction().commit();    //提交事务
        session.close();    //关闭session
    }

    //删除学生
    private void delete(){
        Session session = sessionFactory.openSession();
        session.beginTransaction();    

        Student student = (Student) session.get(Student.class, 1L);
        session.delete(student);

        session.getTransaction().commit();
        session.close();
    }

    //更新学生
    private void update(){
        Session session = sessionFactory.openSession();
        session.beginTransaction();    

        Student student = (Student) session.get(Student.class, 6L);
        student.setName("张三22");
        session.save(student);

        session.getTransaction().commit();
        session.close();
    }

    //查找所有学生
    private void getAllStudents(){
        Session session = sessionFactory.openSession();
        session.beginTransaction();    

        String hql = "from Student";
        Query query = session.createQuery(hql);
        List<Student> studentList = query.list();
        for(Student student : studentList){
            System.out.println(student);
        }

        session.getTransaction().commit();
        session.close();
    }

    public static void main(String[] args) {
        StudentTest studentTest = new StudentTest();
//        studentTest.add();
//        studentTest.delete();
//        studentTest.update();
        studentTest.getAllStudents();
    }
}

hibernate.cfg.xml中加入Student映射（为了方便后面，也加入了Teacher）：

<?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>

        <!--数据库连接设置 -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>

        <!-- 方言 -->
        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>

        <!-- 控制台显示SQL -->
        <property name="show_sql">true</property>

        <!-- 自动更新表结构 -->
        <property name="hbm2ddl.auto">update</property>

        <mapping resource="com/cy/model/Student.hbm.xml"/>
        <mapping class="com.cy.model.Teacher"/>
    </session-factory>

</hibernate-configuration>

StudentTest.java运行main函数，结果：

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三、注解版CRUD 实现　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

1.注解版CRUD：注解版的很方便，官方也推荐使用；

2.运行测试程序，hibernate会根据映射关系，如有没有表的话，自动创建表。（如果配置了hbm2ddl.auto为update）；

这里是对Teacher类进行注解的配置，然后进行CRUD操作:

com.cy.model.Teacher.java:

package com.cy.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

//@Entity代表Teacher是一个映射实体
@Entity
@Table(name="t_teacher")
public class Teacher {
    private long id;
    private String name;

    //@Id代表id是一个主键
    //@GenericGenerator配置主键生成策略 name是起个名字，strategy是具体的策略;
    //@GeneratedValue配置生成策略为@GenericGenerator的名字
    @Id
    @GeneratedValue(generator="_native")
    @GenericGenerator(name="_native",strategy="native")
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Teacher [id=" + id + ", name=" + name + "]";
    }

}

将Teacher类加入hibernate.cfg.xml：

<mapping class="com.cy.model.Teacher"/>

com.cy.service.TeacherTest.java测试代码：

package com.cy.service;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;

import com.cy.model.Teacher;
import com.cy.util.HibernateUtil;

public class TeacherTest {

    private static SessionFactory sessionFactory = HibernateUtil.getSessionFactory();

    //添加老师
    private void add(){
        Session session = sessionFactory.openSession();    //生成一个session
        session.beginTransaction();        //开启事务

        Teacher s = new Teacher();
        s.setName("张三");
        session.save(s);

        session.getTransaction().commit();    //提交事务
        session.close();    //关闭session
    }

    //删除老师
    private void delete(){
        Session session = sessionFactory.openSession();
        session.beginTransaction();    

        Teacher Teacher = (Teacher) session.get(Teacher.class, 1L);
        session.delete(Teacher);

        session.getTransaction().commit();
        session.close();
    }

    //更新老师
    private void update(){
        Session session = sessionFactory.openSession();
        session.beginTransaction();    

        Teacher Teacher = (Teacher) session.get(Teacher.class, 4L);
        Teacher.setName("张老师22");
        session.save(Teacher);

        session.getTransaction().commit();
        session.close();
    }

    //查找所有老师
    private void getAllTeachers(){
        Session session = sessionFactory.openSession();
        session.beginTransaction();    

        String hql = "from Teacher";
        Query query = session.createQuery(hql);
        List<Teacher> TeacherList = query.list();
        for(Teacher Teacher : TeacherList){
            System.out.println(Teacher);
        }

        session.getTransaction().commit();
        session.close();
    }

    public static void main(String[] args) {
        TeacherTest TeacherTest = new TeacherTest();
//        TeacherTest.add();
//        TeacherTest.delete();
//        TeacherTest.update();
        TeacherTest.getAllTeachers();
    }
}

测试结果和StudentTest结果差不多，不再说明了。打印出来的语句也基本一样的。