數(shù)據(jù)庫(kù)中存在一個(gè)email字段，并允許其中存儲(chǔ)多個(gè)email地址，各地址之間使用 ; 分割，但是在POJO中，為了便于處理，email定義為一個(gè)List對(duì)象。
如何將String字段映射為L(zhǎng)ist類(lèi)型，Hibernate并沒(méi)有提供原生支持，需要我們實(shí)現(xiàn)自己的UserType。
1.數(shù)據(jù)庫(kù)定義
DROP
?
TABLE
?t_user_mail;
CREATE
?
TABLE
?t_user_mail?(
???????id?
INT
?
NOT
?
NULL
?AUTO_INCREMENT
?????,?name?
VARCHAR
(
50
)
?????,?age?
INT
?????,?email?
VARCHAR
(
300
)
?????,?
PRIMARY
?
KEY
?(id)
);
2.
實(shí)現(xiàn)了UserType的自定義數(shù)據(jù)類(lèi)型類(lèi)EMailList
package
?cn.blogjava.usertype;
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.apache.commons.lang.StringUtils;
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};
????
????
public
?
int
[]?sqlTypes()?{
????????
//
?TODO?Auto-generated?method?stub
????????
return
?TYPES;
????}
????
public
?Class?returnedClass()?{
????????
//
?TODO?Auto-generated?method?stub
????????
return
?List.
class
;
????}
????
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
?i?
=
?
0
;?i?
<
?xlist.size();?i
++
)?{
????????????????String?str1?
=
?(String)xlist.get(i);
????????????????String?str2?
=
?(String)ylist.get(i);
????????????????
if
(
!
str1.equals(str2))?
return
?
false
;
????????????}
????????????
return
?
true
;
????????}
????????
return
?
false
;
????}
????
public
?
int
?hashCode(Object?arg0)?
throws
?HibernateException?{
????????
//
?TODO?Auto-generated?method?stub
????????
return
?
0
;
????}
????
public
?Object?nullSafeGet(ResultSet?rs,?String[]?names,?Object?owner)
????????????
throws
?HibernateException,?SQLException?{
????????String?value?
=
?(String)Hibernate.STRING.nullSafeGet(rs,?names[
0
]);
????????
if
(value?
!=
?
null
)?{
????????????
return
?parse(value);
????????}?
else
?{
????????????
return
?
null
;
????????}
????}
????
public
?
void
?nullSafeSet(PreparedStatement?st,?Object?value,?
int
?index)
????????????
throws
?HibernateException,?SQLException?{
????????
if
(value?
!=
?
null
)?{
????????????String?str?
=
?assemble((List)value);
????????????Hibernate.STRING.nullSafeSet(st,?str,?index);
????????}?
else
?{
????????????Hibernate.STRING.nullSafeSet(st,?value,?index);
????????}
????}
????
public
?Object?deepCopy(Object?value)?
throws
?HibernateException?{
????????List?sourceList?
=
?(List)value;
????????List?targetList?
=
?
new
?ArrayList();
????????targetList.addAll(sourceList);
????????
return
?targetList;
????}
????
public
?
boolean
?isMutable()?{
????????
//
?TODO?Auto-generated?method?stub
????????
return
?
false
;
????}
????
public
?Serializable?disassemble(Object?arg0)?
throws
?HibernateException?{
????????
//
?TODO?Auto-generated?method?stub
????????
return
?
null
;
????}
????
public
?Object?assemble(Serializable?arg0,?Object?arg1)
????????????
throws
?HibernateException?{
????????
//
?TODO?Auto-generated?method?stub
????????
return
?
null
;
????}
????
public
?Object?replace(Object?arg0,?Object?arg1,?Object?arg2)
????????????
throws
?HibernateException?{
????????
//
?TODO?Auto-generated?method?stub
????????
return
?
null
;
????}
????
????
private
?String?assemble(List?emailList)?{
????????StringBuffer?strBuf?
=
?
new
?StringBuffer();
????????
for
?(
int
?i?
=
?
0
;?i?
<
?emailList.size()
-
1
;?i
++
)?{
????????????strBuf.append((String)emailList.get(i)).append(SPLITTER);????????????
????????}
????????strBuf.append(emailList.get(emailList.size()
-
1
));
????????
return
?strBuf.toString();
????}
????
????
private
?List?parse(String?value)?{
????????String[]?strs?
=
?StringUtils.split(value,?SPLITTER);
????????List?emailList?
=
?
new
?ArrayList();
????????
for
?(
int
?i?
=
?
0
;?i?
<
?strs.length;?i
++
)?{
????????????emailList.add(strs[i]);
????????}
????????
return
?emailList;
????}
}
3.
配置文件TUserMail.hbm.xml
<?xml?version="1.0"?>
<!DOCTYPE?hibernate-mapping?PUBLIC?"-//Hibernate/Hibernate?Mapping?DTD?3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<!--?
????????Auto-generated?mapping?file?from
????????the?hibernate.org?cfg2hbm?engine
-->
????<class?name="cn.blogjava.usertype.TUserMail"?table="t_user_mail"?catalog="sample">
????????<id?name="id"?type="integer">
????????????<column?name="id"?/>
????????????<generator?class="native"?/>
????????</id>
????????<property?name="name"?type="string">
????????????<column?name="name"?length="50"?/>
????????</property>
????????<property?name="age"?type="integer">
????????????<column?name="age"?/>
????????</property>
????????<property?name="email"?type="cn.blogjava.usertype.EMailList">
????????????<column?name="email"?length="300"?/>
????????</property>
????</class>
</hibernate-mapping>
4.
在hibernate.cfg.xml載入TUserMail.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="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
????????<property?name="hibernate.connection.password">1234</property>
????????<property?name="hibernate.connection.url">jdbc:mysql://localhost:3306/sample</property>
????????<property?name="hibernate.connection.username">root</property>
????????<property?name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
????????<mapping?resource="cn/blogjava/start/TUser.hbm.xml"?/>
????????<mapping?resource="cn/blogjava/usertype/TUserMail.hbm.xml"?/>
????</session-factory>
</hibernate-configuration>
5.
測(cè)試類(lèi)HibernateTest.java
package?cn.blogjava.usertype;
import?java.util.ArrayList;
import?java.util.List;
import?junit.framework.Assert;
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;
public?class?HibernateTest?extends?TestCase?{
????
????Session?session?=?null;
????/**
?????*?JUnit中的setUp方法在TestCase初始化的時(shí)候會(huì)自動(dòng)調(diào)用
?????*?一般用于初始化公用資源
?????*/
????protected?void?setUp()?{
????????try?{
????????????/**
?????????????*?可以采用hibernate.properties或者h(yuǎn)ibernate.cfg.xml
?????????????*?配置文件的初始化代碼
?????????????*?
?????????????*?采用hibernate.properties
?????????????*?Configuration?config?=?new?Configuration()；
?????????????*?config.addClass(TUser.class);
?????????????*/
????????????
????????????//采用hibernate.cfg.xml配置文件，與上面的方法對(duì)比，兩個(gè)差異
????????????//1.Configuration的初始化方式
????????????//2.xml
????????????Configuration?config?=?new?Configuration().configure();
????????????SessionFactory?sessionFactory?=?config.buildSessionFactory();
????????????session?=?sessionFactory.openSession();
????????????
????????}?catch?(HibernateException?e)?{
????????????//?TODO:?handle?exception
????????????e.printStackTrace();
????????}????????
????}
????/**
?????*?JUnit中的tearDown方法在TestCase執(zhí)行完畢的時(shí)候會(huì)自動(dòng)調(diào)用
?????*?一般用于釋放資源
?????*/????
????protected?void?tearDown()?{
????????try?{
????????????session.close();????????
????????}?catch?(HibernateException?e)?{
????????????//?TODO:?handle?exception
????????????e.printStackTrace();
????????}????????
????}????
????
????/**
?????*?對(duì)象持久化測(cè)試(Insert方法)
?????*/????????
????public?void?testInsert()?{
????????Transaction?tran?=?null;
????????try?{
????????????tran?=?session.beginTransaction();
????????????TUserMail?user?=?new?TUserMail();
????????????user.setName("byf");
????????????List?list?=?new?ArrayList();
????????????list.add("baiyf@msn.com");
????????????list.add("bexy@163.com");
????????????user.setEmail(list);
????????????session.save(user);
????????????session.flush();
????????????tran.commit();
????????????Assert.assertEquals(user.getId().intValue()>0?,true);
????????}?catch?(HibernateException?e)?{
????????????//?TODO:?handle?exception
????????????e.printStackTrace();
????????????Assert.fail(e.getMessage());
????????????if(tran?!=?null)?{
????????????????try?{
????????????????????tran.rollback();
????????????????}?catch?(Exception?e1)?{
????????????????????//?TODO:?handle?exception
????????????????????e1.printStackTrace();
????????????????}
????????????}
????????}
????}
????
????/**
?????*?對(duì)象讀取測(cè)試(Select方法)
?????*/????????????
????public?void?testSelect(){
????????String?hql?=?"?from?TUserMail?where?name='byf'";
????????try?{
????????????List?userList?=?session.createQuery(hql).list();
????????????TUserMail?user?=?(TUserMail)userList.get(0);
????????????List?mailList?=?user.getEmail();
????????????Assert.assertEquals((String)mailList.get(0),?"baiyf@msn.com");
????????????Assert.assertEquals((String)mailList.get(1),?"bexy@163.com");
????????}?catch?(Exception?e)?{
????????????//?TODO:?handle?exception
????????????e.printStackTrace();
????????????Assert.fail(e.getMessage());
????????}
????}
}
運(yùn)行測(cè)試代碼，觀察數(shù)據(jù)庫(kù)中，可以發(fā)現(xiàn)email地址信息已經(jīng)以";"分隔的形式保存。同時(shí)，在數(shù)據(jù)讀取時(shí)，我們也無(wú)需面對(duì)原始的";"分隔字符串，轉(zhuǎn)而只需要處理List類(lèi)型數(shù)據(jù)即可。
posted on 2006-07-05 14:46
knowhow 閱讀(298)
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