Hibernate映射自訂資料類型

Hibernate映射自訂資料類型

資料庫中存在一個email欄位，並允許其中儲存多個email地址，各地址之間使用 ; 分割，但是在POJO中，為了便於處理，email定義為一個List對象。
如何將String欄位對應為List類型，Hibernate並沒有提供原生支援，需要我們實現自己的UserType。
1.資料庫定義

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.
實現了UserType的自訂資料類型類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.
設定檔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.
測試類別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初始化的時候會自動調用     * 一般用於初始化公用資源     */    protected void setUp() {        try {            /**             * 可以採用hibernate.properties或者hibernate.cfg.xml             * 設定檔的初始化代碼             *              * 採用hibernate.properties             * Configuration config = new Configuration()；             * config.addClass(TUser.class);             */                        //採用hibernate.cfg.xml設定檔，與上面的方法對比，兩個差異            //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執行完畢的時候會自動調用     * 一般用於釋放資源     */        protected void tearDown() {        try {            session.close();                } catch (HibernateException e) {            // TODO: handle exception            e.printStackTrace();        }            }            /**     * 對象持久化測試(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();                }            }        }    }        /**     * 對象讀取測試(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());        }    }}

運行測試代碼，觀察資料庫中，可以發現email地址資訊已經以";"分隔的形式儲存。同時，在資料讀取時，我們也無需面對原始的";"分隔字串，轉而只需要處理List類型資料即可。