UserType用法1

UserType是一个Hibernate提供的一个 接口，可以用它来自定义类型；写个简单的例子，用户有Email属性，当然为了安全考虑，我们可以允许用户设定多个email，也可以独立建立一个email，然后将其和user关联起来，但是仅仅为了一个属性，就建立一个表，从系统分配的角度来看，这样很浪费；那么我们需要自定义一个类型；看下联系的实例：

 

EmailList：

package com.keith;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
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,java.io.Serializable {
	private List emails;
	private static final String SPLITTER = ";";

	public int[] sqlTypes() {
		return new int[] { Hibernate.STRING.sqlType() };
	}

	/** 从二级缓存中取这个对象数据时要调用的方法 */
	public Object assemble(Serializable arg0, Object arg1)
			throws HibernateException {
		return arg0;
	}

	/** hibernate把这个数据放入二级缓存时要调用的方法 */
	public Serializable disassemble(Object arg0) throws HibernateException {
		return (Serializable) arg0;
	}

	/** 这是用于Hibernate缓存生成的快照 */
	public Object deepCopy(Object value) throws HibernateException {
		List sourcelist = (List) value;
		List targetlist = new ArrayList();
		targetlist.addAll(sourcelist);
		return targetlist;
	}

	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 {
		return arg0.hashCode();
	}

	/** 告诉hibernate这个类型是不可变的。有微小的性能优化 */
	public boolean isMutable() {
		return false;
	}

	/** 从JDBC的ResultSet读取属性值。这个方法是在从数据库查询数据时用到。 */
	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;
		}
	}

	/** 将属性的值设置到PreparedStatement。 */
	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);
		}
	}

	/** 处理脱管对象状态的合并。 */
	public Object replace(Object original, Object target, Object owner)
			throws HibernateException {
		return original;
	}

	/** 告诉Hibernate这个UserType用来映射的数据类型。 */
	public Class returnedClass() {
		return List.class;
	}

	private String assemble(List list) {
		StringBuffer strBuf = new StringBuffer();
		if (list.size() > 1) {
			for (int i = 0; i < list.size() - 1; i++) {
				strBuf.append(list.get(i)).append(SPLITTER);
			}
			strBuf.append(list.get(list.size() - 1));
		} else if (list.size() == 1) {
			strBuf.append(list.get(0));
		}
		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;
	}
}

 

Tuser：

 

package com.keith;

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

public class Tuser implements Serializable {

	private Integer uId;
	private String uName;
	private List email = new ArrayList();

	public Tuser() {
	}

	public List getEmail() {
		return email;
	}

	public void setEmail(List email) {
		this.email = email;
	}

	public Integer getuId() {
		return uId;
	}

	public void setuId(Integer uId) {
		this.uId = uId;
	}

	public String getuName() {
		return uName;
	}

	public void setuName(String uName) {
		this.uName = uName;
	}

}

 

Tuser.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 package="com.keith">

	<class name="Tuser" table="tUser">
	
		<id name="uId" column="uId">
			<generator class="native" />
		</id>
		
		<property name="uName" column="uName"/>
		<property name="email" type="com.keith.EmailList"></property>
	</class>
</hibernate-mapping>

 

测试代码：

 

                Tuser tUser = new Tuser();
		tUser.setuName("keith");
		List email = new ArrayList();
		email.add("[e-mail]");
		email.add("[e-mail]");
		tUser.setEmail(email);
		session.save(tUser);
		session.getTransaction().commit();

 看下数据库；