hibernate注解-属性级别注解

属性级别注解

添加方式：

写在属性字段上面

写在属性的get访问器的上面

@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getXxx()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

@SequenceGenerator

@GeneratedValue

@GeneratedValue(strategy=GenerationType,generator=""):可选，用于定义主键生成策略

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

@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，默认情形属性名称一致

nullable:可选，表示该字段是否允许为null,默认为true

unique:可选，表示该字段是否为唯一标识，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，默认值225，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INSERTRT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。对于已经创建

就不可以更改的字段，该属性非常有用

@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

@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

@Lob

@Version

@Basic

@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

务必将其标示为@Transient，否则ORM框架默认其注解为@Basic

实例：
hibernate.properties配置：

<!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>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<!--
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql:///hibernate_struts_stumanager</property>
-->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mypage</property>

<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">root</property>
<property name="hibernate.show_sql">false</property>
<property name="hibernate.hbm2ddl.auto">create</property>
<!-- 	<property name="hibernate_current_session_context_class">thread</property> -->
<property name="current_session_context_class">thread</property>
<mapping class="com.entity.Students"/>
</session-factory>
</hibernate-configuration>

实体类Student：

package com.entity;

import java.io.Serializable;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;//JPA注解
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
*/
//@Entity//
//@Entity(name="t_students")//如果不添加名字，则默认与实体类名字相同，如果想要自行设置表明，就需要自己进行添加
@Entity
@Table(name="t_students1",schema="mypage")
public class Students implements Serializable{
@Id
//	     @GeneratedValue
//	     @GeneratedValue(strategy=GenerationType.AUTO)//与@GeneratedValue结果相同，字符串类型不能指定为AUTO类型
//         private int sid; //学号
//	     @GeneratedValue(generator="sid")
//	     @GenericGenerator(name="sid",strategy="assigned")
//	     @Column(length=11)
//	     private String sid;
@EmbeddedId
private StudentPK pk;
//	     @Id
//

//	     @Column(length=11)
private String sname;//姓名
private String gender;//性别
private Date birthday;//出生日期
private String major;//专业
private Address add;
@Transient     //表示该字段不会被ORM映射到表里的字段
private double salary;//薪水
public Students(){

}

public Students(StudentPK pk, String sname, String gender,
Date date, String major,Address add,double salary) {
//			super();
this.pk = pk;
this.sname = sname;
this.gender = gender;
this.birthday = date;
this.major = major;
this.add = add;
this.salary = salary;
}
public StudentPK getPk() {
return pk;
}

public void setPk(StudentPK 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;
}

public Address getAdd() {
return add;
}

public void setAdd(Address add) {
this.add = add;
}

public double getSalary() {
return salary;
}

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

}

StudentPK实体类：

package com.entity;

import java.io.Serializable;

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

@Embeddable
public class StudentPK implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
@Column(length=18)
private String id;//身份证号
@Column(length=8)
private String sid;//学号

public StudentPK(){

}

public StudentPK(String id, String sid) {
this.id = id;
this.sid = sid;
}

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;
}

@Override
public boolean equals(Object obj) {
// TODO Auto-generated method stub
return super.equals(obj);
}

@Override
public int hashCode() {
// TODO Auto-generated method stub
return super.hashCode();
}

}

地址类：

package com.entity;

import javax.persistence.Embeddable;
import javax.persistence.Embedded;

// 地址类
@Embeddable //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
public class Address {
private String postCode;//邮编
private String address;//地址
private String phone;//联系电话
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;
}
@Embedded
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;
}

}

测试类：

package com.entity;

import java.util.Date;
import java.util.EnumSet;

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.Test;

public class TestStudents {
@Test
public void testShemaExport(){
//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 sessionFactory = config.buildSessionFactory(serviceRegistry);
SchemaExport export = new SchemaExport(config);
export.create(true,true);
}
@Test
public void addStudents(){
//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 sessionFactory = config.buildSessionFactory(serviceRegistry);
//创建会话
Session session = sessionFactory.getCurrentSession();
//创建事务
Transaction tx = session.beginTransaction();
Address add = new Address("700005","河南理工大学","15039117115");
StudentPK pk = new StudentPK("012345678912345678","55555555");

Students s = new Students(pk,"张三丰","男",new Date(),"太极拳",add,7899);
session.save(s);
tx.commit();
// 	   SchemaExport export = new SchemaExport(config);
//        export.create(true,true);
}

}