usertype的详细解释和使用实例

 usertype的详细解释和使用实例

java 代码

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import net.sf.hibernate.HibernateException;

/**
 * @author hy-he
 *
 */
public interface UserType {

 /**
  * 返回UserType所映射字段的SQL类型（java.sql.Types)
  * 返回类型为int[]，其中包含了映射个字段的SQL类型代码
  * (UserType可以映射到一个或者多个字段)
  * @return
  */
 public int[]sqlTypes();


 /**
  * UserType.nullSafeGet()所返回的自定义数据类型
  * @return
  */
 public Class returnedClass();


 /**
  * 自定义数据类型的比对方法
  * 此方法将用作脏数据检查，参数x、y分别为数据的两个副本
  * 如果equals方法返回false,则Hibernate将认为数据发生变化,并将变化更新到数据库表中
  * @param x
  * @param y
  * @return
  * @throws HibernateException
  */
 public boolean equals(Object x,Object y)throws HibernateException;


 /**
  * 从JDBC ResultSet读取数据,将其转换为自定义类型后返回
  * (此方法要求对克能出现null值进行处理)
  * names中包含了当前自定义类型的映射字段名称
  * @param rs
  * @param names
  * @param owner
  * @return
  * @throws HibernateException
  * @throws SQLException
  */
 public Object nullSafeGet(ResultSet rs,String[] names,Object owner)throws HibernateException,SQLException;


 /**
  * 本方法将在Hibernate进行数据保存时被调用
  * 我们可以通过PreparedStateme将自定义数据写入到对应的数据库表字段
  * @param st
  * @param value
  * @param index
  * @throws HibernateException
  * @throws SQLException
  */
 public void nullSafeSet(PreparedStatement st,Object value,int index)throws HibernateException,SQLException;


 /**
  * 提供自定义类型的完全复制方法
  * 本方法将用构造返回对象
  * 当nullSafeGet方法调用之后，我们获得了自定义数据对象，在向用户返回自定义数据之前，
  * deepCopy方法将被调用，它将根据自定义数据对象构造一个完全拷贝，并将此拷贝返回给用户
  * 此时我们就得到了自定义数据对象的两个版本，第一个是从数据库读出的原始版本，其二是我们通过
  * deepCopy方法构造的复制版本，原始的版本将有Hibernate维护，复制版由用户使用。原始版本用作
  * 稍后的脏数据检查依据；Hibernate将在脏数据检查过程中将两个版本的数据进行对比（通过调用
  * equals方法），如果数据发生了变化（equals方法返回false），则执行对应的持久化操作
  *
  * @param value
  * @return
  * @throws HibernateException
  */
 public Object deppCopy(Object value)throws HibernateException;


 /**
  * 本类型实例是否可变
  * @return
  */
 public boolean isMutable();
}

1.实现UserType接口的EMailList自定义类型

java 代码

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 net.sf.hibernate.Hibernate;
import net.sf.hibernate.HibernateException;
import net.sf.hibernate.UserType;
import net.sf.hibernate.hql.Parser;

/**
 * @author hy-he
 *
 */
public class EMailList implements UserType {
 private List emails;
 private static final String SPLITTER = ";";
 private static final int[] TYPES = new int[]{
  Types.VARCHAR
 };
 /* (non-Javadoc)
  * @see net.sf.hibernate.UserType#sqlTypes()
  */
 public int[] sqlTypes() {
  // TODO Auto-generated method stub
  return TYPES;
 }

 /* (non-Javadoc)
  * @see net.sf.hibernate.UserType#returnedClass()
  */
 public Class returnedClass() {
  // TODO Auto-generated method stub
  return List.class;
 }

 /* (non-Javadoc)
  * @see net.sf.hibernate.UserType#equals(java.lang.Object, java.lang.Object)
  */
 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;
 }

 /* (non-Javadoc)
  * @see net.sf.hibernate.UserType#nullSafeGet(java.sql.ResultSet, java.lang.String[], java.lang.Object)
  */
 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;
  }
 }

 /* (non-Javadoc)
  * @see net.sf.hibernate.UserType#nullSafeSet(java.sql.PreparedStatement, java.lang.Object, int)
  */
 public void nullSafeSet(PreparedStatement st, Object value, int index) throws HibernateException, SQLException {
  System.out.println("Set method excecuted");
  if(value != null){
   String str = assemble((List)value);
   Hibernate.STRING.nullSafeSet(st,str,index);
  }else{
   Hibernate.STRING.nullSafeSet(st,value,index);
  }

 }

 /* (non-Javadoc)
  * @see net.sf.hibernate.UserType#deepCopy(java.lang.Object)
  */
 public Object deepCopy(Object value) throws HibernateException {
  List sourcelist = (List)value;
  List targetlist = new ArrayList();
  targetlist.addAll(sourcelist);
  return targetlist;
 }

 /* (non-Javadoc)
  * @see net.sf.hibernate.UserType#isMutable()
  */
 public boolean isMutable() {
  // TODO Auto-generated method stub
  return false;
 }
 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();
 }
 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;
 }
}

2.POJO：

java 代码

import java.io.Serializable;
import java.util.List;

/**
 * @author hy-he
 * @hibernate.class
 * table = "USER_TYPE_USER"
 */
public class UserTypeUser implements Serializable {
 private Long id;
 private String name;
 private Integer age;
 private List email = new ArrayList();
 /**
  * @hibernate.id
  * column = "USER_ID"
  * generator-class = "increment"
  * @return
  */
 public Long getId() {
  return id;
 }
 /**
  * @hibernate.property
  * column = "AGE"
  * @return
  */
 public Integer getAge() {
  return age;
 }
 /**
  * @hibernate.property
  * column = "EMAIL"
  * type = "hibernate.usertype.EMailList"
  * @return
  */
 public List getEmail() {
  return email;
 }
 /**
  * @hibernate.property
  * column = "NAME"
  * @return
  */
 public String getName() {
  return name;
 }
 public void setAge(Integer age) {
  this.age = age;
 }
 public void setEmail(List email) {
  this.email = email;
 }
 public void setId(Long id) {
  this.id = id;
 }
 public void setName(String name) {
  this.name = name;
 }

}

3.xml：

xml 代码

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
    <class
        name="hibernate.usertype.UserTypeUser"
        table="USER_TYPE_USER"
        dynamic-update="false"
        dynamic-insert="false"
    >

        <id
            name="id"
            column="USER_ID"
            type="java.lang.Long"
        >
            <generator class="increment">
            </generator>
        </id>

        <property
            name="age"
            type="java.lang.Integer"
            update="true"
            insert="true"
            access="property"
            column="AGE"
        />

        <property
            name="email"
            type="hibernate.usertype.EMailList"
            update="true"
            insert="true"
            access="property"
            column="EMAIL"
        />

        <property
            name="name"
            type="java.lang.String"
            update="true"
            insert="true"
            access="property"
            column="NAME"
        />

        <!--
            To add non XDoclet property mappings, create a file named
                hibernate-properties-UserTypeUser.xml
            containing the additional properties and place it in your merge dir.
        -->

    </class>

</hibernate-mapping>

4.运用：

java 代码

insert方法：

public static void insertUser() throws HibernateException {
  UserTypeUser user = new UserTypeUser();
  user.setAge(new Integer(23));
  user.setName("Test UserType");
  user.getEmail().add("[e-mail]");
  user.getEmail().add("[e-mail]");
  user.getEmail().add("[e-mail]");
  user.getEmail().add("[e-mail]");
  Session session = HibernateUtil.currentSession();
  Transaction tx = session.beginTransaction();
  session.save(user);

  tx.commit();
  HibernateUtil.closeSession();
 }

display方法：

 public static void display() throws HibernateException {
  Session session = HibernateUtil.currentSession();
  List users = session.find("from UserTypeUser");
  HibernateUtil.closeSession();

  for (ListIterator iterator = users.listIterator(); iterator.hasNext();) {
   UserTypeUser pu = (UserTypeUser) iterator.next();
   System.out.println(pu.getName());
   List emails = pu.getEmail();
   for(int i = 0;i<emails.size();i++){
    System.out.println(emails.get(i));
   }
  }
 }