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慕课网_《Hibernate注解》学习总结

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摘要:时间年月日星期二说明本文部分内容均来自慕课网。文件如下在目录下,创建文件指定映射文件的路径注解映射实体类可选,对应数据库中的一个表。

时间:2017年07月11日星期二
说明:本文部分内容均来自慕课网。@慕课网:http://www.imooc.com
教学源码:无
学习源码:https://github.com/zccodere/s...

第一章:类级别注解 1-1 本章简介

本章简介

Hibernate注解简介
JPA与Hibernate的关系
Hibernate注解分类
@Entity
@Table
@Embeddable
schema与catalog

Hibernate注解简介

使用注解的目的:为了简化繁琐的ORM映射文件(*.hbm)的配置

JPA与Hibernate的关系

什么是JPA
    全称Java Persistence API
    JPA注解是JavaEE的规范和标准
JPA和Hibernate的关系:

JPA是标准接口
Hibernate是实现,但是其功能是JPA的超集

Hibernate如何实现与JPA的关系
    通过hibernate-annotation
    hibernate-entitymanager
    hibernate-core三个组件来实现
一般在实际开发中,优先考虑使用JPA注解

这样更有利于程序的移植和扩展
Hibernate注解的分类

类级别注解
属性级别注解
映射关系注解

类级别注解

@Entity:表示一个实体,一个实体对应数据库一张表
@Table:配置表的属性
@Embeddable:表示当前类是一个嵌入类
1-2 准备工作

回顾hibernate.cfg.xml

创建一个名为hibernateca的maven项目,并添加相关依赖。POM文件如下


  4.0.0

  com.myimooc
  hibernateca
  0.0.1-SNAPSHOT
  jar

  hibernateca
  http://maven.apache.org


        UTF-8
        UTF-8
    

    
        
        
            org.hibernate
            hibernate-core
            4.2.4.Final
        

        
        
            mysql
            mysql-connector-java
            5.1.38
        
        
        
            junit
            junit
            4.10
            test
        
    

    
        
            
                org.apache.maven.plugins
                maven-compiler-plugin
                
                    1.8
                    1.8
                
            
        
    

在src/main/ resources目录下,创建hibernate.cfg.xml文件




    
        org.hibernate.dialect.MySQLDialect
        com.mysql.jdbc.Driver
        root
        root
        
            
        
        true
        update
         
        
         

    
1-3 @Entity注解

@Entity

@Entity:映射实体类
@Entity(name=”tableName”)
name:可选,对应数据库中的一个表。若表名与实体类名相同,则可以省略
注意:使用@Entity时必须指定实体类的主键属性

代码演示

1.编写Students实体类

package com.myimooc.hibernateca.entity;

import java.util.Date;

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

/**
 * 学生实体类
 * @author ZhangCheng on 2017-07-12
 *
 */
//JPA注解
@Entity(name="t_students")
public class Students {
    
    /** 学号 */
    @Id
    private Integer sid;
    /** 姓名 */
    private String sname;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    
    @Override
    public String toString() {
        return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday
                + ", major=" + major + "]";
    }
    
    public Students() {
        super();
    }
    public Students(Integer sid, String sname, String gender, Date birthday, String major) {
        super();
        this.sid = sid;
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
        this.address = address;
    }

    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}

2.配置映射


 

3.编写StudentTest测试类

package com.myimooc.hibernateca.entity;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

/**
 * 单元测试类
 * @author ZhangCheng on 2017-07-12
 *
 */
public class StudentsTest {
    
    @Test
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        @SuppressWarnings("unused")
        SessionFactory sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
        SchemaExport export = new SchemaExport(config);
        
        export.create(true, true);
    }
    
}
1-4 @Table注解

@Table

@Table(name=””,catalog=””,schema=””)
@Entity配置使用,只能标注在实体的class定义处,表示实体对应的数据库表的信息
name:可选,映射表的名称,默认表名和实体名称一致,只有在不一致的情况下才需要指定表名
catalog:可选,表示目录Catalog名称,默认为Catalog(“”)
schema:可选,表示模式Schema名称,默认为Schema(“”)

schema与catalog示意图

schema与catalog

从实现的角度来看,各种数据库系统对Catalog和Schema的支持和实现方式千差万别的

供应商的支持和实现

代码演示,修改Student类如下

package com.myimooc.hibernateca.entity;

import java.util.Date;

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

/**
 * 学生实体类
 * @author ZhangCheng on 2017-07-12
 *
 */
//JPA注解
//@Entity(name="t_students")

@Entity
@Table(name="t_students",schema="hibernatemtm")
public class Students {
    
    /** 学号 */
    @Id
    private Integer sid;
    /** 姓名 */
    private String sname;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    
    @Override
    public String toString() {
        return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday
                + ", major=" + major + "]";
    }
    
    public Students() {
        super();
    }
    public Students(Integer sid, String sname, String gender, Date birthday, String major) {
        super();
        this.sid = sid;
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
    }

    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}
1-5 @Embeddable注解

@Embeddable
@Embeddable表示一个非Entity类可以嵌入到另一个Entity类中作为属性而存在

代码演示

1.编写Address类

package com.myimooc.hibernateca.entity;

import javax.persistence.Embeddable;

/**
 * 地址类(嵌入类)
 * @author ZhangCheng on 2017-07-12
 *
 */
// 表示是一个嵌入类,这个类的对象在另一个实体类中充当属性
@Embeddable
public class Address {
    
    /** 邮编 */
    private String postCode;
    /** 地址 */
    private String address;
    /** 联系电话 */
    private String phone;
    
    @Override
    public String toString() {
        return "Address [postCode=" + postCode + ", address=" + address + ", phone=" + phone + "]";
    }
    
    public Address() {
    }
    
    public Address(String postCode, String address, String phone) {
        this.postCode = postCode;
        this.address = address;
        this.phone = phone;
    }
    
    public String getPostCode() {
        return postCode;
    }
    public void setPostCode(String postCode) {
        this.postCode = postCode;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public String getPhone() {
        return phone;
    }
    public void setPhone(String phone) {
        this.phone = phone;
    }
    
    
}

2.修改Student类如下

package com.myimooc.hibernateca.entity;

import java.util.Date;

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

/**
 * 学生实体类
 * @author ZhangCheng on 2017-07-12
 *
 */
//JPA注解
//@Entity(name="t_students")

@Entity
@Table(name="t_students",schema="hibernatemtm")
public class Students {
    
    /** 学号 */
    @Id
    private Integer sid;
    /** 姓名 */
    private String sname;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    /** 地址 */
    private Address address;
    
    @Override
    public String toString() {
        return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday
                + ", major=" + major + "]";
    }
    
    public Students() {
        super();
    }
    public Students(Integer sid, String sname, String gender, Date birthday, String major,Address address) {
        super();
        this.sid = sid;
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
        this.address = address;
    }
    
    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}
第二章:属性级别注解 2-1 本章简介

Hibernate属性级别注解

添加方式:写在属性字段方面 或 写在属性的get访问器的上面
@Id
-@SequenceGenerator
@GeneratedValue
@Column
@Embedded
@EmbeddedId
-@Lob
-@Version
-@Basic
@Transient
2-2 @Id注解

@Id

@Id:必须,定义了映射到数据库表的主键的属性,
一个实体类可以有一个或者多个属性被映射为主键,
可置于主键属性或者get方法前
注意:如果有多个属性定义为主键属性,
该实体类必须实现serializable接口

拷贝hibernateca项目,重命名为hibernateaa,POM与Hibernate配置文件均相同

2-3 @GeneratedValue注解(一)

@GeneratedValue

@GeneratedValue(strategy=GenerationType,generator=””)
可选,用户定义主键生成策略
strategy表示主键生成策略,取值有
    GenerationType.AUTO:根据底层数据库自动选择(默认)
    GenerationType.INDENTITY:根据数据库的Identity字段生成
    GenerationType.SEQUENCE:使用Sequence来决定主键的取值
    GenerationType.TABLE:使用指定表来决定主键取值,结合@TableGenerator使用

使用示例

2-4 @GeneratedValue注解(二)

代码演示

1.修改Students类

package com.myimooc.hibernateaa.entity;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;

import org.hibernate.annotations.GenericGenerator;

/**
 * 学生实体类
 * @author ZhangCheng on 2017-07-12
 *
 */

@SuppressWarnings("unused")
@Entity
@Table(name="t_students",schema="hibernatemtm")
public class Students {
    
    /** 学号 */
    /* 方式一:使用自动生成主键
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer sid;
    */
    
    /* 方式二:使用手工赋值方式生成主键
    @Id
    @GeneratedValue(generator="sid")
    @GenericGenerator(name="sid",strategy="assigned")//
    @Column(length=8)
    private String sid;
    */
    
    /* 方式三:使用复合主键 */
    @EmbeddedId
    private StudentsPK pk;
    
    /** 姓名 */
    private String sname;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    /** 薪水 */
    @Transient // 表示该属性不会被ORM映射到表里的字段
    private double salary;
    /** 地址 */
    @Embedded
    private Address address;
    
    @Override
    public String toString() {
        return "Students [pk=" + pk + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday + ", major="
                + major + ", salary=" + salary + ", address=" + address + "]";
    }
    
    public Students() {
        super();
    }
    
    public Students(StudentsPK pk, String sname, String gender, Date birthday, String major,Address address) {
        super();
        this.pk = pk;
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
        this.address = address;
    }
    
    public Students(StudentsPK pk, String sname, String gender, Date birthday, String major, double salary,
            Address address) {
        super();
        this.pk = pk;
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
        this.salary = salary;
        this.address = address;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
    public StudentsPK getPk() {
        return pk;
    }

    public void setPk(StudentsPK pk) {
        this.pk = pk;
    }

    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}
2-5 @GeneratedValue注解(三)

代码演示

1.修改StudentsTest类

package com.myimooc.hibernateaa.entity;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 单元测试类
 * @author ZhangCheng on 2017-07-12
 *
 */
@SuppressWarnings("unused")
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
//        SchemaExport export = new SchemaExport(config);
//        export.create(true, true);
    }
    
    @Test
    public void addStudents(){
        // 创建会话
        Session session = sessionFactory.getCurrentSession();
        // 创建事务
        Transaction tx = session.beginTransaction();
        
        // 创建一个学生对象
        Address address = new Address("700005","湖北武当山","18991167346");
//        Students s = new Students("S0000002","张三丰","男",new Date(),"太极拳",address);
//        
//        session.save(s);
        tx.commit();
        
    }
    
    @Test
    public void addStudentsByPk(){
        // 创建会话
        Session session = sessionFactory.getCurrentSession();
        // 创建事务
        Transaction tx = session.beginTransaction();
        
        // 创建一个学生对象
        Address address = new Address("700005","湖北武当山","18991167346");
        // 创建学生主键对象
        StudentsPK pk = new StudentsPK();
        pk.setId("123456789012345678");
        pk.setSid("1235241231");
        
        Students s = new Students(pk,"张三丰","男",new Date(),"太极拳",address);
        session.save(s);
        tx.commit();
        
    }
}
2-6 @Column注解

@Column

@Column:可将属性映射到列,使用该注解来覆盖默认值
@Column描述了数据库表中该字段的详细定义
这对于根据JPA注解生成数据库表结构的工具非常有作用

常用属性

name:可选,表示数据库表中该字段的名称,默认与属性名称一致
nullable:可选,表示该字段是否允许为null,默认为true
unique:可选,表示该字段是否是唯一标识,默认为false
length:可选,表示该字段的大小,仅对String类型的字段有效,默认为255
(如果是主键不能使用默认值)
insertable:可选,表示在ORM框架执行插入操作时,该字段是否应出现INSERT语句中,默认为true
updateable:可选,表示在ORM框架执行更新操作时,该字段是否应该出现在UPDATE语句中,默认为true
    对于一经创建就不可以更改的字段,该属性非常有用,如对于birthday字段
2-7 @Embedded注解

@Embedded

@Embedded是注释属性的,表示该属性的类是嵌入类
注意:同时嵌入类也必须标注@Embeddable注解
2-8 @EmbeddedId注解

@EmbeddedId

@EmbeddedId使用嵌入式主键类实现复合主键
注意:嵌入式主键类
必须实现Serializable接口
必须有默认的public无参数的构造方法
必须覆盖equals和hashCode方法

代码演示

1.编写StudentsPK类

package com.myimooc.hibernateaa.entity;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Embeddable;

/**
 * 学生主键类
 * @author ZhangCheng on 2017-07-12
 *
 */
@Embeddable
public class StudentsPK implements Serializable{
    
    private static final long serialVersionUID = 1L;
    
    /** 省份证号码 */
    @Column(length=18)
    private String id;
    /** 学号 */
    @Column(length=10)
    private String sid;
    
    public StudentsPK() {
    }

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

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((id == null) ? 0 : id.hashCode());
        result = prime * result + ((sid == null) ? 0 : sid.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        StudentsPK other = (StudentsPK) obj;
        if (id == null) {
            if (other.id != null)
                return false;
        } else if (!id.equals(other.id))
            return false;
        if (sid == null) {
            if (other.sid != null)
                return false;
        } else if (!sid.equals(other.sid))
            return false;
        return true;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getSid() {
        return sid;
    }

    public void setSid(String sid) {
        this.sid = sid;
    }

    
}

2.修改Students类

package com.myimooc.hibernateaa.entity;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;

import org.hibernate.annotations.GenericGenerator;

/**
 * 学生实体类
 * @author ZhangCheng on 2017-07-12
 *
 */

@SuppressWarnings("unused")
@Entity
@Table(name="t_students",schema="hibernatemtm")
public class Students {
    
    /** 学号 */
    /* 方式一:使用自动生成主键
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer sid;
    */
    
    /* 方式二:使用手工赋值方式生成主键
    @Id
    @GeneratedValue(generator="sid")
    @GenericGenerator(name="sid",strategy="assigned")//
    @Column(length=8)
    private String sid;
    */
    
    /* 方式三:使用复合主键 */
    @EmbeddedId
    private StudentsPK pk;
    
    /** 姓名 */
    private String sname;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    /** 薪水 */
    @Transient // 表示该属性不会被ORM映射到表里的字段
    private double salary;
    /** 地址 */
    @Embedded
    private Address address;
    
    @Override
    public String toString() {
        return "Students [pk=" + pk + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday + ", major="
                + major + ", salary=" + salary + ", address=" + address + "]";
    }
    
    public Students() {
        super();
    }
    
    public Students(StudentsPK pk, String sname, String gender, Date birthday, String major,Address address) {
        super();
        this.pk = pk;
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
        this.address = address;
    }
    
    public Students(StudentsPK pk, String sname, String gender, Date birthday, String major, double salary,
            Address address) {
        super();
        this.pk = pk;
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
        this.salary = salary;
        this.address = address;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
    public StudentsPK getPk() {
        return pk;
    }

    public void setPk(StudentsPK pk) {
        this.pk = pk;
    }

    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}

3.修改StudentsTest类

package com.myimooc.hibernateaa.entity;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 单元测试类
 * @author ZhangCheng on 2017-07-12
 *
 */
@SuppressWarnings("unused")
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
//        SchemaExport export = new SchemaExport(config);
//        export.create(true, true);
    }
    
    @Test
    public void addStudents(){
        // 创建会话
        Session session = sessionFactory.getCurrentSession();
        // 创建事务
        Transaction tx = session.beginTransaction();
        
        // 创建一个学生对象
        Address address = new Address("700005","湖北武当山","18991167346");
//        Students s = new Students("S0000002","张三丰","男",new Date(),"太极拳",address);
//        
//        session.save(s);
        tx.commit();
        
    }
    
    @Test
    public void addStudentsByPk(){
        // 创建会话
        Session session = sessionFactory.getCurrentSession();
        // 创建事务
        Transaction tx = session.beginTransaction();
        
        // 创建一个学生对象
        Address address = new Address("700005","湖北武当山","18991167346");
        // 创建学生主键对象
        StudentsPK pk = new StudentsPK();
        pk.setId("123456789012345678");
        pk.setSid("1235241231");
        
        Students s = new Students(pk,"张三丰","男",new Date(),"太极拳",address);
        session.save(s);
        tx.commit();
        
    }
}
2-9 @Transient注解

@Transient

可选,表示该属性并非一个到数据库表的字段的映射,ORM框架将忽略该属性,如果一个属性并非数据库表的字段映射,就务必将其表示为@Transient,否则ORM框架默认其注解为@Basic
第三章:关联映射注解 3-1 本章简介

简介

一对一单向外键关联
一对一双向外键关联
一对一单向外键联合主键
多对一单向外键关联
一对多单向外键关联
一对多双向外键关联
多对多单向外键关联
多对多双向外键关联
3-2 实体之间的关系

实体之间的映射关系

一对一:一个公民对应一个身份证号码
一对多(多对一):一个公民有多个银行账号
多对多:一个学生有多个老师,一个老师有多个学生
3-3 一对一单向外键关联(一)

一对一单向外键

@OneToOne(cascade=CascadeType.ALL)
@JoinColumn(name=”pid”,unique=true)
注意:保存时应该先保存外键对象,再保存主表对象

拷贝hibernateca项目,重命名为hibernatera,POM与Hibernate配置文件均相同

代码演示

1.编写Students类

package com.myimooc.hibernatera.onetoonefk;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

/**
 * 一对一单向外键关联
 * 学生实体类
 * @author ZhangCheng on 2017-07-12
 *
 */
@Entity
public class Students {
    
    /** 学号 */
    @Id
    @GeneratedValue
    private Integer sid;
    
    /** 身份证类 */
    @OneToOne(cascade=CascadeType.ALL)
    @JoinColumn(name="pid",unique=true)
    private IdCard card;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    
    @Override
    public String toString() {
        return "Students [sid=" + sid + ", sname=" + ", gender=" + gender + ", birthday=" + birthday
                + ", major=" + major + "]";
    }
    
    public Students() {
    }
    
    public Students(IdCard card, String gender, Date birthday, String major) {
        super();
        this.card = card;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
    }

    public Students(IdCard card,Integer sid,  String gender, Date birthday, String major) {
        this.card = card;
        this.sid = sid;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
    }
    
    public IdCard getCard() {
        return card;
    }

    public void setCard(IdCard card) {
        this.card = card;
    }

    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}

2.编写IdCard类

package com.myimooc.hibernatera.onetoonefk;

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

import org.hibernate.annotations.GenericGenerator;

/**
 * 一对一单向外键关联
 * 身份证实体类
 * @author ZhangCheng on 2017-07-12
 *
 */
@Entity
public class IdCard {
    
    @Id
    @GeneratedValue(generator = "pid")
    @GenericGenerator(name="pid",strategy="assigned")
    @Column(length=18)
    /** 身份证号码 */
    private String pid;
    /** 学生的姓名 */
    private String sname;
    
    public IdCard() {
    }
    public IdCard(String pid, String sname) {
        this.pid = pid;
        this.sname = sname;
    }
    public String getPid() {
        return pid;
    }
    public void setPid(String pid) {
        this.pid = pid;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    
}

3.修改Hibernate配置文件




    
        org.hibernate.dialect.MySQLDialect
        com.mysql.jdbc.Driver
        root
        root
        
            
        
        true
        update
        thread
         
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
         
        
        
    

4.编写StudentsTest类

package com.myimooc.hibernatera.onetoonefk;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 一对一双单外键关联
 * 单元测试类
 * @author ZhangCheng on 2017-07-12
 *
 */
@SuppressWarnings("unused")
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
//        SchemaExport export = new SchemaExport(config);
//        
//        export.create(true, true);
    }
    
    
}
3-4 一对一单向外键关联(二)

代码演示

1.修改StudentsTest类

package com.myimooc.hibernatera.onetoonefk;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 一对一双单外键关联
 * 单元测试类
 * @author ZhangCheng on 2017-07-12
 *
 */
@SuppressWarnings("unused")
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
//        SchemaExport export = new SchemaExport(config);
//        
//        export.create(true, true);
    }
    
    /**
     * 一对一单向外键关联保存测试
     */
    @Test
    public void addStudents(){
        
        Session session = sessionFactory.getCurrentSession();
        
        // 生成一个身份证对象
        IdCard card = new IdCard("123456789012345678","张无忌");
        Transaction tx = session.beginTransaction();
        // 生成学生对象
        Students s = new Students(card, "男", new Date(), "太极拳");
        // 先保存身份证类的对象
        session.save(card);
        session.save(s);
        
        tx.commit();
        
    }
    
}
3-5 一对一双向外键关联

一对一双向外键

主控方的配置同一对一单向外键关联相同
@OneToOne(mappedBy=”card”)//被控方
双向关联,必须设置mappedBy属性。因为双向关联只能交给一方去控制
不可能在双方都设置外键保存关联关系,否则双方都无法保存

代码演示

1.编写Students类

package com.myimooc.hibernatera.onetoonebfk;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

/**
 * 一对一双向外键关联
 * 学生实体类
 * @author ZhangCheng on 2017-07-12
 *
 */
@Entity
public class Students {
    
    /** 学号 */
    @Id
    @GeneratedValue
    private Integer sid;
    
    /** 身份证类 */
    @OneToOne(cascade=CascadeType.ALL)
    @JoinColumn(name="pid",unique=true)
    private IdCard card;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    
    @Override
    public String toString() {
        return "Students [sid=" + sid + ", sname=" + ", gender=" + gender + ", birthday=" + birthday
                + ", major=" + major + "]";
    }
    
    public Students() {
    }
    
    public Students(IdCard card, String gender, Date birthday, String major) {
        super();
        this.card = card;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
    }

    public Students(IdCard card,Integer sid,  String gender, Date birthday, String major) {
        this.card = card;
        this.sid = sid;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
    }
    
    public IdCard getCard() {
        return card;
    }

    public void setCard(IdCard card) {
        this.card = card;
    }

    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}

2.编写IdCard类

package com.myimooc.hibernatera.onetoonebfk;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;

import org.hibernate.annotations.GenericGenerator;

/**
 * 一对一双向外键关联
 * 身份证实体类
 * @author ZhangCheng on 2017-07-12
 *
 */
@Entity
public class IdCard {
    
    @Id
    @GeneratedValue(generator = "pid")
    @GenericGenerator(name="pid",strategy="assigned")
    @Column(length=18)
    /** 身份证号码 */
    private String pid;
    /** 学生的姓名 */
    private String sname;
    /** 学生的引用 */
    @OneToOne(mappedBy="card")
    private Students stu;
    
    public Students getStu() {
        return stu;
    }
    public void setStu(Students stu) {
        this.stu = stu;
    }
    public IdCard() {
    }
    public IdCard(String pid, String sname) {
        this.pid = pid;
        this.sname = sname;
    }
    public String getPid() {
        return pid;
    }
    public void setPid(String pid) {
        this.pid = pid;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    
}

3.修改hibernate配置文件




    
        org.hibernate.dialect.MySQLDialect
        com.mysql.jdbc.Driver
        root
        root
        
            
        
        true
        update
        thread
         
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
         
        
        
    

4.编写StudentsTest类

package com.myimooc.hibernatera.onetoonebfk;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 一对一双向外键关联
 * 单元测试类
 * @author ZhangCheng on 2017-07-12
 *
 */
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    //@Test
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
        SchemaExport export = new SchemaExport(config);
        
        export.create(true, true);
    }
    
    /**
     * 一对一双向外键关联保存测试
     */
    @Test
    public void addStudents(){
        
        Session session = sessionFactory.getCurrentSession();
        
        // 生成一个身份证对象
        IdCard card = new IdCard("123456789012345678","张无忌");
        Transaction tx = session.beginTransaction();
        // 生成学生对象
        Students s = new Students(card, "男", new Date(), "太极拳");
        // 先保存身份证类的对象
        session.save(card);
        session.save(s);
        
        tx.commit();
        
    }
    
}
3-6 一对一单向外键联合主键

一对一双向外键联合主键

创建主键类
主键类必须实现serializable接口,重写hashCode()和equals()方法
主键类:@Embeddable
实体类:@EmbeddedId
3-7 多对一单向外键关联(一)

多对一单向外键

多方持有一方的引用,比如:多个学生对应一个班级(多对一)
在多方添加以下注解
@ManyToOne(cascade={CascadeType.ALL},fetch=FetchType.EAGER)
@JoinColumn(name=”cid”,referencedColumnName=”CID”)

代码演示

1.编写Students类

package com.myimooc.hibernatera.manytoonefk;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;

/**
 * 多对一单向外键关联
 * 学生实体类(多方)
 * @author ZhangCheng on 2017-07-13
 *
 */
@Entity
public class Students {
    
    /** 学号 */
    @Id
    @GeneratedValue
    private Integer sid;
    /** 学生姓名 */
    private String sname;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;
    // 多方持有一方的引用
    @ManyToOne(cascade={CascadeType.ALL},fetch=FetchType.EAGER)// 配置级联关系和抓取策略
    @JoinColumn(name="cid",referencedColumnName="CID") // 指定外键
    private ClassRoom classRoom;
    
    @Override
    public String toString() {
        return "Students [sid=" + sid + ", sname=" + ", gender=" + gender + ", birthday=" + birthday
                + ", major=" + major + "]";
    }
    
    public Students() {
    }
    
    public Students(String sname, String gender, Date birthday, String major) {
        super();
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public ClassRoom getClassRoom() {
        return classRoom;
    }

    public void setClassRoom(ClassRoom classRoom) {
        this.classRoom = classRoom;
    }

    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}

2.编写ClassRoom类

package com.myimooc.hibernatera.manytoonefk;

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

import org.hibernate.annotations.GenericGenerator;

/**
 * 多对一单向外键关联
 * 班级实体类(一方)
 * @author ZhangCheng on 2017-07-13
 *
 */
@Entity
public class ClassRoom {
    
    /** 班级编号 */
    @Id
    @GeneratedValue(generator="cid")
    @GenericGenerator(name="cid",strategy="assigned")
    @Column(length=4)
    private String cid;
    /** 班级名字 */
    private String cname;
    
    public ClassRoom() {
    }

    public ClassRoom(String cid, String cname) {
        this.cid = cid;
        this.cname = cname;
    }

    public String getCid() {
        return cid;
    }

    public void setCid(String cid) {
        this.cid = cid;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }

    @Override
    public String toString() {
        return "ClassRoom [cid=" + cid + ", cname=" + cname + "]";
    }
    
    
}

3.修改hibernate配置文件




    
        org.hibernate.dialect.MySQLDialect
        com.mysql.jdbc.Driver
        root
        root
        
            
        
        true
        update
        thread
         
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
         
        
        
    

4.编写StudentsTest类

package com.myimooc.hibernatera.manytoonefk;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 多对一单向外键关联
 * 单元测试类
 * @author ZhangCheng on 2017-07-13
 *
 */
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    //@Test
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
        SchemaExport export = new SchemaExport(config);
        
        export.create(true, true);
    }
    
    
}
3-8 多对一单向外键关联(二)

代码演示
1.修改StudentsTest类

package com.myimooc.hibernatera.manytoonefk;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 多对一单向外键关联
 * 单元测试类
 * @author ZhangCheng on 2017-07-13
 *
 */
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    //@Test
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        // 创建服务注册对象
        ServiceRegistry ServiceRegistry = new ServiceRegistryBuilder()
            .applySettings(config.getProperties()).buildServiceRegistry();
        // 生成sessionFactory
        sessionFactory = config.buildSessionFactory(ServiceRegistry);
        
        SchemaExport export = new SchemaExport(config);
        
        export.create(true, true);
    }
    
    @Test
    public void addStudents(){
        
        Session session = sessionFactory.getCurrentSession();
        Transaction tx = session.beginTransaction();
        
        // 创建班级对象
        ClassRoom c1 = new ClassRoom("C001","软件工程");
        ClassRoom c2 = new ClassRoom("C002","网络工程");
        // 创建学生对象
        Students s1 = new Students("张三","男", new Date(), "计算机");
        Students s2 = new Students("李四","男", new Date(), "计算机");
        Students s3 = new Students("王五","女", new Date(), "计算机");
        Students s4 = new Students("赵六","女", new Date(), "计算机");
        
        s1.setClassRoom(c1);
        s2.setClassRoom(c1);
        s3.setClassRoom(c2);
        s4.setClassRoom(c2);
        
        // 先保存班级
        session.save(c1);
        session.save(c2);
        session.save(s1);
        session.save(s2);
        session.save(s3);
        session.save(s4);
        
        tx.commit();
        
    }
    
}
3-9 一对多单向外键关联

一对多单向外键

一方持有多方的集合,一个班级有多个学生(一对多)
在一方添加以下注解
@OneToMany(cascade={CascadeType.ALL},fetch=FetchType.LAZY)
@JoinColumn(name=”cid”)

抓取策略总结

多对一时候
多方设置EAGER:表示积极加载
一方设置LAZY:表示懒加载

代码演示

1.编写Students类

package com.myimooc.hibernatera.onetomanyfk;

import java.util.Date;

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

/**
 * 一对多单向外键关联
 * 学生实体类(多方)
 * @author ZhangCheng on 2017-07-13
 *
 */
@Entity
public class Students {
    
    /** 学号 */
    @Id
    @GeneratedValue
    private Integer sid;
    /** 学生姓名 */
    private String sname;
    /** 性别 */
    private String gender;
    /** 出生日期 */
    private Date birthday;
    /** 专业 */
    private String major;

    @Override
    public String toString() {
        return "Students [sid=" + sid + ", sname=" + ", gender=" + gender + ", birthday=" + birthday
                + ", major=" + major + "]";
    }
    
    public Students() {
    }
    
    public Students(String sname, String gender, Date birthday, String major) {
        super();
        this.sname = sname;
        this.gender = gender;
        this.birthday = birthday;
        this.major = major;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public Integer getSid() {
        return sid;
    }
    public void setSid(Integer sid) {
        this.sid = sid;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getMajor() {
        return major;
    }
    public void setMajor(String major) {
        this.major = major;
    }
}

2.编写ClassRoom类

package com.myimooc.hibernatera.onetomanyfk;

import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;

import org.hibernate.annotations.GenericGenerator;

/**
 * 一对多单向外键关联
 * 班级实体类(一方)
 * @author ZhangCheng on 2017-07-13
 *
 */
@Entity
public class ClassRoom {
    
    /** 班级编号 */
    @Id
    @GeneratedValue(generator="cid")
    @GenericGenerator(name="cid",strategy="assigned")
    @Column(length=4)
    private String cid;
    /** 班级名字 */
    private String cname;
    
    // 一方持有多方的集合
    @OneToMany(cascade={CascadeType.ALL},fetch=FetchType.LAZY)
    @JoinColumn(name="cid")
    private Set stus;
    
    public ClassRoom() {
    }

    public ClassRoom(String cid, String cname) {
        this.cid = cid;
        this.cname = cname;
    }

    public Set getStus() {
        return stus;
    }

    public void setStus(Set stus) {
        this.stus = stus;
    }

    public String getCid() {
        return cid;
    }

    public void setCid(String cid) {
        this.cid = cid;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }

    @Override
    public String toString() {
        return "ClassRoom [cid=" + cid + ", cname=" + cname + "]";
    }
    
    
}

3.修改hibernate配置文件

同上

4.编写StudentsTest类

package com.myimooc.hibernatera.onetomanyfk;

import java.util.Date;
import java.util.HashSet;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Before;
import org.junit.Test;

/**
 * 一对多单向外键关联
 * 单元测试类
 * @author ZhangCheng on 2017-07-13
 *
 */
public class StudentsTest {
    
    private SessionFactory sessionFactory = null;
    
    @Before
    //@Test
    public void schemaExportTest(){
        // 创建hibernate配置对象
        Configuration config = new Configuration().configure();
        /           
               
                                           
                       
                 

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