EJB---->一对一映射

一个人（Person）只有唯一的身份证号(IDCard)，Person 与IDCard 是一对一关系。

需要映射的数据库表

一对一关系需要在关系维护端（owner side）的@OneToOne 注释中定义mappedBy 属性。在关系被维护端（inverseside）建立外键列指向关系维护端的主键列

Person.java

package com.foshanshop.ejb3.bean;
import java.io.Serializable;
import java.util.Date;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@SuppressWarnings("serial")
@Entity
@Table(name = "Person")
public class Person implements Serializable{
private Integer personid;
private String name;
private boolean sex;
private Short age;
private Date birthday;
private IDCard idcard;
@Id
@GeneratedValue
public Integer getPersonid() {
return personid;
}
public void setPersonid(Integer personid) {
this.personid = personid;
}
@Column(name = "PersonName",nullable=false,length=32)
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Column(nullable=false)
public boolean getSex() {return sex;
}
public void setSex(boolean sex) {
this.sex = sex;
}
@Column(nullable=false)
public Short getAge() {
return age;
}
public void setAge(Short age) {
this.age = age;
}
@Temporal(value=TemporalType.DATE)
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@OneToOne(optional = true,cascade = CascadeType.ALL, mappedBy = "person")
public IDCard getIdcard() {
return idcard;
}
public void setIdcard(IDCard idcard) {
this.idcard = idcard;
}
}

@OneToOne 注释指明Person 与IDCard 为一对一关系，@OneToOne 注释五个属性：targetEntity、cascade、fetch、optional 和mappedBy, 前四个属性的具体含义与@ManyToOne 注释的同名属性，fetch 属性默认值是FetchType.EAGER。mappedBy 属性的具体含义与@OneToMany 注释的同名属性相同。
上面的optional = true 设置idcard 属性可以为null,也就是允讦没有身份证，未成年人就是没有身份证的。
IDCard.javaIDCard.java

package com.foshanshop.ejb3.bean;
import java.io.Serializable;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;
@SuppressWarnings("serial")
@Entity
@Table(name = "IDCard")
public class IDCard implements Serializable{
private Integer id;
private String cardno;
private Person person;
public IDCard() {
}
public IDCard(String cardno) {
this.cardno = cardno;
}
@Id
@GeneratedValue
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
@Column(nullable=false,length=18,unique = true)
public String getCardno() {
return cardno;
}
public void setCardno(String cardno) {
this.cardno = cardno;
}
@OneToOne(optional = false, cascade = CascadeType.REFRESH)
@JoinColumn(name = "Person_ID", referencedColumnName = "personid",unique = true)
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
}

@OneToOne 注释指明IDCard 与Person 为一对一关系，IDCard 是关系被维护端，optional = false 设置person 属性
值不能为null，也就是身份证必须有对应的主人。@JoinColumn(name = "Person_ID", referencedColumnName =
"personid",unique = true)指明IDCard 对应表的Person_ID列作为外键与Person对应表的personid列进行关联, unique
= true 指明Person_ID 列的值不可重复。
OneToOneDAOBea

package com.foshanshop.ejb3.impl;
import java.util.Date;
import javax.ejb.Remote;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import com.foshanshop.ejb3.OneToOneDAO;
import com.foshanshop.ejb3.bean.IDCard;
import com.foshanshop.ejb3.bean.Person;
@Stateless
@Remote ({OneToOneDAO.class})
public class OneToOneDAOBean implements OneToOneDAO {
@PersistenceContext
protected EntityManager em;
public void insertPerson(String name, boolean sex,short age, Date birthday,String cardID) {
Person person = new Person();
person.setName(name);
person.setSex(sex);
person.setAge(Short.valueOf(age));
person.setBirthday(birthday);
IDCard idcard = new IDCard(cardID);
idcard.setPerson(person);
person.setIdcard(idcard);
em.persist(person);
}
public Person getPersonByID(Integer personid) {
Person person = em.find(Person.class, personid);
return person;
}
public void updatePersonInfo(Integer personid, String newname, String newIDcard) {
Person person = em.find(Person.class, personid);
if (person!=null) {
person.setName(newname);
if (person.getIdcard()!=null){
person.getIdcard().setCardno(newIDcard);
}
em.merge(person);
}
}
public void deletePerson(Integer personid) {
Person person = em.find(Person.class, personid);
if (person!=null) em.remove(person);
}
}

OneToOneTest.jsp

import="com.foshanshop.ejb3.OneToOneDAO,
com.foshanshop.ejb3.bean.*,
javax.naming.*,
java.util.Date,
java.text.SimpleDateFormat,
java.util.*"%>
<%
Properties props = new Properties();
props.setProperty("java.naming.factory.initial",
"org.jnp.interfaces.NamingContextFactory");
props.setProperty("java.naming.provider.url", "localhost:1099");
props.setProperty("java.naming.factory.url.pkgs", "org.jboss.naming");
InitialContext ctx = new InitialContext(props);
try {
String outformate = "<font color=blue>CMD>>Out>></font> ";
OneToOneDAO oneToonedao = (OneToOneDAO) ctx.lookup("OneToOneDAOBean/remote");
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
SimpleDateFormat formatter1 = new SimpleDateFormat("MMddhhmmss");
String endno = formatter1.format(new Date()).toString();
oneToonedao.insertPerson("黎活明", true, (short)26,formatter.parse("1980-9-30"),
"44011"+endno);
//添加时请注意，身份证号不要重复，因为数据库字段身份证号是唯一的
Person person = oneToonedao.getPersonByID(new Integer(1));
if (person!=null){
out.println(outformate +"寻找编号为1的人员<br>");
out.println("姓名:"+ person.getName() +" 身份证："+
person.getIdcard().getCardno() +"<br>");
}else{
out.println("没有找到编号为1的人员<br>");
}
out.println(outformate +"更新编号为1的人员的姓名为李明,身份证号为33012" +endno
+"<br>");
oneToonedao.updatePersonInfo(new Integer(1), "李明", "33012" +endno);
out.println("================删除编号为3的人员==============<br>");
oneToonedao.deletePerson(new Integer(3));
} catch (Exception e) {
out.println(e.getMessage());
}
%>