hibernate注解-属性级别注解
来源：程序员人生 发布时间：2016-07-07 08:54:09 阅读次数：2959次
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，定义了映照到数据库表的主键的属性，1个实体类可以有1个或多个属性被映照为主键，
可置于主键属性或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（默许）
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-可将属性映照到列，使用该注解来覆盖默许值，@Column描写了数据库表中该字段的详细定义，这对根据JPA
注解生成数据库表结构的工具非常有作用。
经常使用属性：
name:可选，表示数据库表中该字段的名称，默许情形属性名称1致
nullable:可选，表示该字段是不是允许为null,默许为true
unique:可选，表示该字段是不是为唯1标识，默许为false
length:可选，表示该字段的大小，仅对String类型的字段有效，默许值225，主键不能使用默许值
insertable:可选，表示在ORM框架履行插入操作时，该字段是不是应出现INSERTRT语句中，默许为true
updateable:可选，表示在ORM框架履行更新操作时，该字段是不是应当出现在UPDATE语句中，默许为true。对已创建
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、必须有默许的public无参数的构造方法、必须覆盖equals和hashCode方法
@Lob
@Version
@Basic
@Transient
可选，表示该属性并不是1个到数据库表的字段的映照，ORM框架将疏忽该属性，如果1个属性并不是数据库表的字段映照，就
务势必其标示为@Transient，否则ORM框架默许其注解为@Basic
实例：
hibernate.properties配置：
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration⑶.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，则默许与实体类名字相同，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;//诞生日期
private String major;//专业
private Address add;
@Transient //表示该字段不会被ORM映照到表里的字段
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1个嵌入类，这个类的对象在另外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3丰","男",new Date(),"太极拳",add,7899);
session.save(s);
tx.commit();
// SchemaExport export = new SchemaExport(config);
// export.create(true,true);
}
}
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