Hibernate實作UserType之例子

說明：由於Hibernate並沒有提供特殊的原生類別當作Mapping欄位(如我們需要List集合之類別)，故Hibernate提供一個UserType Interface讓我們自己實作一個UserType。

實作方法如下：1.於t_user表格中加入一個email欄位，此email儲存資料的方式是以分號";"加以分隔，t_user表格schema如下：




drop table if exists t_user;




create table t_user(

id int(11) auto_increment,

name varchar(50) not null default '',

age int(3),

version int(4),

email varchar(300),

primary key (id));






2.建立一個EMailList類別實作UserType Interface，類別內容如下：


package org.redsaga.usertype;







import java.util.List;

import java.util.ArrayList;

import java.io.Serializable;

import java.sql.Types;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;




import org.hibernate.Hibernate;

import org.hibernate.HibernateException;

import org.hibernate.usertype.UserType;




public class EMailList implements Serializable,UserType {

 private static final char SPLITTER=';';

 


 private static final int[] TYPES = new int[]{Types.VARCHAR};

 


 public boolean isMutable(){

  return false;

 }

 


 public int[] sqlTypes(){

  return TYPES;

 }

 


 public Class returnedClass(){

  return List.class;

 }

 


 /**

  * 建立一個新的List實例，包含原有List實例中的所有元素

  */

 public Object deepCopy(Object value)throws HibernateException{

  List sourceList = (List)value;

  List targetList = new ArrayList();

  targetList.addAll(sourceList);

  return targetList;

 }

 


 /**

  * 判斷email list是否發生改變

  */

 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;

  }else{

   return false;

  }

 }

 


 /**

  * 將以";"分隔的字串解析為一個字串陣例

  *

  * @param value

  * @return List

  */

 public List parse(String value){

  String[] strs = org.apache.commons.lang.StringUtils.split(value, SPLITTER);

  List emailList = new ArrayList();

  for(int i=0;i<strs.length;i++){

   emailList.add(strs[i]);

  }

  return emailList;

 }

 


 /**

  * 將String拼裝為一個字串，以";"分隔巷

  */

 public 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();

 }

 


 /**

  * 從ResultSet中取出email欄位，並將其解析為List類型後回傳

  */

 public Object nullSafeGet(ResultSet rs, String[] names, Object owner)throws HibernateException,SQLException{

  System.out.println("nullSafeGet method executed");

  String value = (String)Hibernate.STRING.nullSafeGet(rs, names[0]);

  if(value!=null){

   return parse(value);

  }else{

   return null;

  }  


 }

 


 /**

  * 將List型的email資訊組裝成字串之後保存到email欄位

  */

 public void nullSafeSet(PreparedStatement st, Object value, int index)throws HibernateException,SQLException{

  System.out.println("nullSafeSet method executed");

  if(value!=null){

   String str = assemble((List)value);

   Hibernate.STRING.nullSafeSet(st, str, index);

  }else{

   Hibernate.STRING.nullSafeSet(st, value, index);

  }

 }

 


 public Object assemble(Serializable cached, Object owner)throws HibernateException{

  return null;  


 }

 


 public Serializable disassemble(Object value)throws HibernateException{

  return null;

 }

 


 public int hashCode(Object x)throws HibernateException{

  return 0;

 }

 


 public Object replace(Object original, Object target, Object owner)throws HibernateException{

  return null;

 }




}

=======================================




3.TUser.java及TUser.hbm.xml內容如下：


package org.redsaga.quickstart;




// Generated 2009/8/6 下午 11:08:15 by Hibernate Tools 3.2.4.GA




import java.util.List;

/**

 * TUser generated by hbm2java

 */

public class TUser implements java.io.Serializable {




 private Integer id;

 private Integer version;

 private String name;

 private Integer age;

 private List email;




 public TUser() {

 }




 public TUser(String name) {

  this.name = name;

 }




 public TUser(String name, Integer age, List email) {

  this.name = name;

  this.age = age;

  this.email = email;

 }




 public Integer getId() {

  return this.id;

 }




 public void setId(Integer id) {

  this.id = id;

 }




 public Integer getVersion() {

  return this.version;

 }




 public void setVersion(Integer version) {

  this.version = version;

 }




 public String getName() {

  return this.name;

 }




 public void setName(String name) {

  this.name = name;

 }




 public Integer getAge() {

  return this.age;

 }




 public void setAge(Integer age) {

  this.age = age;

 }




 public List getEmail() {

  return this.email;

 }




 public void setEmail(List email) {

  this.email = email;

 }




}

=========================================


<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!-- Generated 2009/8/6 ?U?? 11:08:15 by Hibernate Tools 3.2.4.GA -->

<hibernate-mapping>

    <class name="org.redsaga.quickstart.TUser" table="t_user" catalog="manning">

        <id name="id" type="java.lang.Integer">

            <column name="id" />

            <generator class="identity" />

        </id>

        <version name="version" type="java.lang.Integer">

            <column name="version" />

        </version>

        <property name="name" type="string">

            <column name="name" length="50" not-null="true" />

        </property>

        <property name="age" type="java.lang.Integer">

            <column name="age" />

        </property>

        <property name="email" type="org.redsaga.usertype.EMailList">

            <column name="email" length="300" />

        </property>

    </class>

</hibernate-mapping>

==========================================




4.Hibernate.cfg.xml，內容如下：


<?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">org.gjt.mm.mysql.Driver</property>

        <property name="hibernate.connection.password">action</property>

        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/manning</property>

        <property name="hibernate.connection.username">manning</property>

        <property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>

        <!-- 將SQL輸出到Console -->

        <property name="hibernate.show_sql">true</property>

        <!-- 使用JDBC Transaction  -->

        <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property>

        <!-- 將TUser.hbm.xml加到Hibernate.cfg.xml檔案中 -->

<mapping resource="org/redsaga/quickstart/TUser.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

======================================










5.利用JUnit建立一個測試method(testUserType)，內容如下：


 /**
 * testUserType 測試UserType for email欄位是否有效
 * @throws Exception
 */
public void testUserType() throws Exception {
 TUser user=null;
 Transaction tran = null;
 String hql = " from TUser where name='Emma'";
 try{
  tran = session.beginTransaction();
  List emailList = new ArrayList();
  user = new TUser();
  user.setName("Emma");
  user.setAge(19);
  emailList.add("Emma@org.redsaga");
  emailList.add("Emma@yahoo.com.tw");
  user.setEmail(emailList);
  session.save(user);
  session.flush();
  tran.commit();

  List userList = session.createQuery(hql).list();
  //添加一個Email後保存

  for(int i=0;i<userList.size();i++){
   user = (TUser)userList.get(i);
   System.out.println(user.getEmail());
  }
 }catch(HibernateException e){
  e.printStackTrace();
 }
}

==========================================




6.測試結果：

Mysql查詢結果：





console輸出結果：


Hibernate: insert into manning.t_user (version, name, age, email) values (?, ?, ?, ?)

nullSafeSet method executed

Hibernate: select tuser0_.id as id0_, tuser0_.version as version0_, tuser0_.name as name0_, tuser0_.age as age0_, tuser0_.email as email0_ from manning.t_user tuser0_ where tuser0_.name='Emma'

[Emma@org.redsaga, Emma@yahoo.com.tw]