介绍Hibernate使用UserType--ClobStringType

这里介绍Hibernate使用UserType，UserType就是用户自定义类型，这里的类型指的是除了Hibernate定义的那些类型之外的用户自己定义的。

UserType就是用户自定义类型，这里的类型指的是除了Hibernate定义的那些类型之外的用户自己定义的。

一个实现Hibernate使用UserType接口的 email 类如下(里面的每个方法都是必须实现的接口方法，许多都可以复制粘贴的，不复杂)：

/*
* $HeadURL$
* Copyright (c) 2003-2007 Untangle, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* AS-IS and WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, TITLE, or
* NONINFRINGEMENT.? See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*/

package com.untangle.uvm.type;

import java.io.Serializable;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import org.hibernate.HibernateException;
import org.hibernate.usertype.UserType;

/**
* Hibernate <code>UserType</code> for persisting
* <code>InetAddress</code> objects.
*
* @author <a href="mailto:amread@untangle.com">Aaron Read</a>
* @version 1.0
*/
public class InetAddressUserType implements UserType
{
??? private static final int[] SQL_TYPES = { Types.VARCHAR };

??? public int[] sqlTypes() { return SQL_TYPES; }//该类型对应的?sql?类型??
??? public Class<InetAddress> returnedClass() { return InetAddress.class; }

??? public boolean equals(Object x, Object y) //equals方法，这个就不用多说了吧，肯定是要用户自定义的
??? {
??????? if (x == y) { return true; }
??????? if (x == null || y == null) { return false; }
??????? return x.equals(y);
??? }

??? public Object deepCopy(Object value) { return value; } //?完全复制的方法，由于是用户自己定义的类型//所以hibernate并不知道要如何来复制这个类，需要用户自己定义??
??? public boolean isMutable() { return false; }?//?表示本类型实例是否可变，一般是不可变 ?

1. /**?*//**//* ?这才是重头戏！nullSafeGet?和nullSafeSet?是核心所在，对数据的后期处理都在这两个方法里面 ?
2. nullSafeGet?是读取的方法 ?owner?目前没用到过。 ?
3. names?是对应的数据库列名，UserType是可以对应多个列的 ?*/
   ??? public Object nullSafeGet(ResultSet rs, String[] names, Object owner)
   ??????? throws HibernateException, SQLException
   ??? {
   ??????? String name = rs.getString(names[0]);
   
   ??????? if (rs.wasNull()) { return null; }
   
   ??????? try {
   ??????????? return InetAddress.getByName(name);
   ??????? } catch (UnknownHostException exn) {
   ??????????? throw new HibernateException(exn);
   ??????? }
   ??? }
   
1. /**//* ?保存的方法 ?
2. index?是那个?PreparedStatement?的参数序号，一般来说不用管直接往下传 ?value?就是要保存的数据，在这边是一个保存着?email?列表的?List ?
3. */ ?
   ??? public void nullSafeSet(PreparedStatement ps, Object v, int i)
   ??????? throws HibernateException, SQLException
   ??? {
   ??????? if (null == v) {
   ??????????? ps.setNull(i, Types.VARCHAR);
   ??????? } else {
   ??????????? InetAddress addr = (InetAddress)v;
   ??????????? ps.setString(i, addr.getHostAddress());
   ??????? }
   ??? }
   
   ??? public Object replace(Object original, Object target, Object owner)
   ??? {
   ??????? return original;
   ??? }
   
   ??? public Object assemble(Serializable cached, Object owner)
   ??? {
   ??????? return deepCopy(cached);
   ??? }
   
   ??? public Serializable disassemble(Object value)
   ??? {
   ??????? return (Serializable)deepCopy(value);
   ??? }
   
   ??? public int hashCode(Object x)
   ??? {
   ??????? return x.hashCode();
   ??? }
   }
   

?

?

下来是对应pojo类，这个类用了相应的注解

package com.untangle.uvm.logging;

import java.net.InetAddress;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;

import org.hibernate.annotations.Type;

import com.untangle.uvm.logging.PipelineEvent;
import com.untangle.uvm.logging.SyslogBuilder;
import com.untangle.uvm.logging.SyslogPriority;
import com.untangle.uvm.node.PipelineEndpoints;

/**
?* Log event from the denormalized reports.n_cpd_block_events reports table
?*
?* @author Sebastien Delafond
?* @version 1.0
?*/
@Entity
??? @org.hibernate.annotations.Entity(mutable=false)
??? @Table(name="n_cpd_block_events", schema="reports")
??? @SuppressWarnings("serial")
??? public class CpdBlockEventsFromReports extends LogEvent
??? {
??????? private InetAddress clientAddress;
??????? private InetAddress serverAddress;
??????? private Integer clientPort;
??????? private Integer serverPort;
??????? private Integer clientIntf;
??????? private Integer proto;

??????? @Column(name="client_address")
??????? @Type(type="com.untangle.uvm.type.InetAddressUserType")//自定义的usertype
??????? public InetAddress getClientAddress() { return clientAddress; }
??????? public void setClientAddress(InetAddress clientAddress) { this.clientAddress = clientAddress; }

??????? @Column(name="server_address")
??????? @Type(type="com.untangle.uvm.type.InetAddressUserType")
??????? public InetAddress getServerAddress() { return serverAddress; }
??????? public void setServerAddress(InetAddress serverAddress) { this.serverAddress = serverAddress; }

??????? @Column(name="client_port")
??????? public Integer getClientPort() { return clientPort; }
??????? public void setClientPort(Integer clientPort) { this.clientPort = clientPort; }

??????? @Column(name="server_port")
??????? public Integer getServerPort() { return serverPort; }
??????? public void setServerPort(Integer serverPort) { this.serverPort = serverPort; }

??????? @Column(name="proto")
??????? public Integer getProto() { return proto; }
??????? public void setProto(Integer proto) { this.proto = proto; }

??????? @Column(name="client_intf")
??????? public Integer getClientIntf() { return clientIntf; }
??????? public void setClientIntf(Integer clientIntf) { this.clientIntf = clientIntf; }

??????? public void appendSyslog(SyslogBuilder sb) // FIXME: not called for now
??????? {
??????? }

??????? @Transient
??????? public String getSyslogId()
??????? {
??????????? return ""; // FIMXE ?
??????? }

??????? @Transient
??????? public SyslogPriority getSyslogPriority()
??????? {
??????????? // FIXME
??????????? return SyslogPriority.INFORMATIONAL;
??????? }

??? }