Hibernate映射自定义数据类型
数据库中存在一个email字段，并允许其中存储多个email地址，各地址之间使用 ; 分割，但是在POJO中，为了便于处理，email定义为一个List对象。
如何将String字段映射为List类型，Hibernate并没有提供原生支持，需要我们实现自己的UserType。
1.数据库定义
DROP TABLE t_user;
CREATE TABLE t_user (
id INT NOT NULL AUTO_INCREMENT
, name VARCHAR ( 50 )
, age INT
, email VARCHAR ( 300 )
, PRIMARY KEY (id)
);
2.实现了UserType的自定义数据类型类EmailList
package tuser;
import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.ArrayList;
import java.util.List;
import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.usertype.UserType;
public class EmailList implements UserType {
private static final char SPLITTER = ';';
private static final int[] TYPES = new int[]{Types.VARCHAR};
@Override
public int[] sqlTypes() {
return TYPES;
}
@Override
public Class returnedClass() {
return List.class;
}
@Override
public boolean equals(Object x, Object y) throws HibernateException {
if(x == y){
return true;
}
if(x != null && y != null){
List xList = (List)x;
List yList = (List)y;
if(xList.size() != yList.size()){
return false;
}
for(int index = 0; index < xList.size(); index++){
String str1 = (String) xList.get(index);
String str2 = (String) yList.get(index);
if(str1 != str2){
return false;
}
}
return true;
}
return false;
}
@Override
public Object nullSafeGet(ResultSet rs, String[] names, Object owner)
throws HibernateException, SQLException {
String value = Hibernate.STRING.nullSafeGet(rs, names[0]);
if(value != null){
return parse(value);
}else{
return null;
}
}
@Override
public void nullSafeSet(PreparedStatement st, Object value, int index)
throws HibernateException, SQLException {
System.out.println("Set method executed");
if(value != null){
String str = assemble((List)value);
Hibernate.STRING.nullSafeSet(st, str, index);
}else{
Hibernate.STRING.nullSafeSet(st, null, index);
}
}
@Override
public Object deepCopy(Object value) throws HibernateException {
List sourceList = (List)value;
List targetList = new ArrayList();
targetList.addAll(sourceList);
return targetList;
}
@Override
public boolean isMutable() {
return false;
}
/**
* 将String拼装为一个字符串，以“；”分隔
* @param emailList
* @return
*/
private String assemble(List emailList){
StringBuffer strBuf = new StringBuffer();
for(int i = 0; i < emailList.size() - 1; i++){
strBuf.append(emailList.get(i)).append(SPLITTER);
}
strBuf.append(emailList.get(emailList.size() - 1));
return strBuf.toString();
}
/**
* 将以“；”分隔的字符串解析为一个字符串数组
* @param value
* @return
*/
private List parse(String value){
String[] strs = value.split(SPLITTER + "");
List emailList = new ArrayList();
for(int i = 0; i < strs.length; i++){
emailList.add(strs[i]);
}
return emailList;
}
@Override
public Object assemble(Serializable arg0, Object arg1)
throws HibernateException {
return null;
}
@Override
public Serializable disassemble(Object arg0) throws HibernateException {
return null;
}
@Override
public int hashCode(Object arg0) throws HibernateException {
return 0;
}
@Override
public Object replace(Object arg0, Object arg1, Object arg2)
throws HibernateException {
return null;
}
}
3.配置文件TUser.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="tuser.TUser" table="T_USER">
<id name="id" type="java.lang.Integer">
<column name="ID"/>
<generator class="native"></generator>
</id>
<property name="name" type="java.lang.String">
<column name="NAME"/>
</property>
<property name="age" type="java.lang.String">
<column name="AGE"/>
</property>
<property name="email" type="tuser.EmailList">
<column name="EMAIL"/>
</property>
</class>
</hibernate-mapping>
4.在hibernate.cfg.xml载入TUser.hbm.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<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">
system
</property>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="javax.persistence.validation.mode">
none
</property>
<property name="c3p0.min_size">5</property>
<property name="c3p0.max_size">20</property>
<property name="c3p0.timeout">300</property>
<property name="c3p0.max_statements">50</property>
<property name="c3p0.idle_test_period">3000</property>
<property name="show_sql">false</property>
<property name="format_sql">false</property>
<mapping resource="hello/Message.hbm.xml"/>
<mapping resource="user/User.hbm.xml"/>
<mapping resource="tuser/TUser.hbm.xml"/>
</session-factory>
</hibernate-configuration>
5.测试类HibernateTest.java
package test;
import java.util.ArrayList;
import java.util.List;
import junit.framework.TestCase;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;
import tuser.TUser;
import user.User;
public class HibernateTest extends TestCase {
Session session = null;
@Before
protected void setUp() throws Exception {
try {
Configuration configure = new Configuration().configure();
SessionFactory sessionFactory = configure.buildSessionFactory();
session = sessionFactory.openSession();
} catch (HibernateException e) {
e.printStackTrace();
}
}
@After
protected void tearDown() throws Exception {
try {
session.close();
} catch (HibernateException e) {
e.printStackTrace();
}
}
@Test
public void testTUser(){
Transaction tran = null;
try {
tran = session.beginTransaction();
TUser user = new TUser();
user.setName("byf");
List list = new ArrayList();
list.add("[email protected]");
list.add("[email protected]");
user.setEmail(list);
session.save(user);
session.flush();
tran.commit();
Assert.assertEquals(user.getId().intValue()>0 ,true);
} catch (HibernateException e) {
e.printStackTrace();
Assert.fail(e.getMessage());
if(tran != null) {
try {
tran.rollback();
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
}
/**
* 对象读取测试(Select方法)
*/
public void testSelect(){
String hql = " from TUser where name='byf'";
try {
List userList = session.createQuery(hql).list();
TUser user = (TUser)userList.get(0);
List mailList = user.getEmail();
Assert.assertEquals((String)mailList.get(0), "[email protected]");
Assert.assertEquals((String)mailList.get(1), "[email protected]");
} catch (Exception e) {
e.printStackTrace();
Assert.fail(e.getMessage());
}
}
}
6.TUser类
package tuser;
import java.io.Serializable;
import java.util.List;
public class TUser implements Serializable {
private static final long serialVersionUID = 1901560971512450430L;
private Integer id;
private String name;
private Integer age;
private List email;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public List getEmail() {
return email;
}
public void setEmail(List email) {
this.email = email;
}
}
运行测试代码，观察数据库中，可以发现email地址信息已经以";"分隔的形式保存。同时，在数据读取时，我们也无需面对原始的";"分隔字符串，转而只需要处理List类型数据即可。