Hibernate对自定义类型UserType的用法

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Hibernate允许我们自定义映射属性的类型，比如一个学生有联系地址，而联系地址又分为家庭地址和工作地址，我们可以把两个地址信息抽象成一个新的Address类，作为Student的成员变量

数据库结构：

create table typestu (id varchar(32) primary key,name varchar(32),homeaddr varchar(32),workaddr varchar(32));

Hibernate.cfg.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>

jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312&useUnicode=true

</property>

org.hibernate.dialect.MySQLDialect

</property>

<property name="myeclipse.connection.profile">mysql</property>

com.mysql.jdbc.Driver

</property>

org.hibernate.dialect.MySQLDialect

</property>

<property name="current_session_context_class">thread</property>

</session-factory>

</hibernate-configuration>

Pojo

package Search.UserType;

public class Student {

private String id; //标识id

private String name; //学生姓名

private AddressType address;//地址

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public AddressType getAddress() {

return address;

}

public void setAddress(AddressType address) {

this.address = address;

}

自定义类型

package Search.UserType;

import java.io.Serializable;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Types;

import org.apache.commons.lang.builder.EqualsBuilder;

import org.apache.commons.lang.builder.HashCodeBuilder;

import org.hibernate.HibernateException;

import org.hibernate.usertype.UserType;

public class AddressType implements UserType, Serializable {

private String homeAddr;

private String workAddr;

/* 有几个字段就有几个值，这里容易出错，要多注意 */

private static final int[] SQL_TYPES = { Types.VARCHAR, Types.VARCHAR };

/* 这个方法告诉Hibernate在成生DDL时对列采用什么样的SQL语法 */

public int[] sqlTypes() {

return SQL_TYPES;

}

* Hibernate返回什么样的映射类型，与 <property name="address" type="model.AddressType">

* 指定的类一致。事实上也可以把AddressType拆分为两个类，一个类是只携带信息的JavaBean，它里面

* 没有逻辑操作也没有实现UserType（比如AddressBean）；而另一个类实现了UserType，它所面对的就不是现在这个

* AddressType类的homeAddr和homeAddr属性，它面对的是AddressBean。在本例中为了简洁方便，只用了一个类。

public Class returnedClass() {

return AddressType.class;

}

* 表明这个类的实例在创建以后就不可以改变属性。Hibernate能为不可改变的类作一些性能优化。

public boolean isMutable() {

return false;

}

* 由于AddressType是不可变的，所以深拷贝可以直接返回对象引用。拷贝的对象由应用程序使用，而原版对象由Hibernate维护以做脏数据检查

public Object deepCopy(Object value) {

return value; // Address is immutable

}

/* 两个对象是否相等，使用了apache的common工具包来进行属性比对 */

public boolean equals(Object x, Object y) {

if (x == y)

return true;

if (x == null || y == null)

return false;

AddressType add1 = (AddressType) x;

AddressType add2 = (AddressType) y;

return new EqualsBuilder() //使用EqualsBuilder类来方便地进行比对

.append(add1.getHomeAddr(), add2.getHomeAddr()).append(

add2.getWorkAddr(), add2.getWorkAddr()).isEquals();

}

/* 得到hash码 */

public int hashCode(Object x) throws HibernateException {

AddressType address = (AddressType) x;

return new HashCodeBuilder()//使用HashCodeBuilder类来方便地进行比对

.append(address.getHomeAddr()).append(address.getWorkAddr())

.toHashCode();

}

/* 读取数据并组装成一个AddressType对象。names[]中的参数顺序依照映射文件中定义的顺序 */

public Object nullSafeGet(ResultSet rs, String[] names, Object owner)

throws HibernateException, SQLException {

if (rs.wasNull())

return null;

String homeAddr = rs.getString(names[0]);

String schoolAddr = rs.getString(names[1]);

AddressType address = new AddressType(homeAddr, schoolAddr);

return address;

}

/* 保存数据，index的顺序按照映射文件定义的顺序，从0开始。 */

public void nullSafeSet(PreparedStatement st, Object value, int index)

throws HibernateException, SQLException {

AddressType address = (AddressType) value;

if (value == null) {

st.setNull(index, Types.VARCHAR);

st.setNull(index+1, Types.VARCHAR);

} else {

st.setString(index, address.getHomeAddr());

st.setString(index + 1, address.getWorkAddr());

}

System.out.println("Data has been saved! ");

}

/* 当把AddressType类型数据写入二级缓存时，此方法被调用 */

public Serializable disassemble(Object value) throws HibernateException {

return null;

}

/* 当从二级缓存中读取AddressType类型数据时，此方法被调用 */

public Object assemble(Serializable cached, Object owner)

throws HibernateException {

// TODO 自动生成方法存根

return null;

}

public Object replace(Object original, Object target, Object owner)

throws HibernateException {

// TODO 自动生成方法存根

return null;

}

public AddressType() {

super();

}

public AddressType(String homeAddr, String workAddr) {

super();

this.homeAddr = homeAddr;

this.workAddr = workAddr;

}

/**

* @return 返回 sQL_TYPES。

public static int[] getSQL_TYPES() {

return SQL_TYPES;

}

/**

* @return 返回 homeAddr。

public String getHomeAddr() {

return homeAddr;

}

/**

* @param homeAddr

* 要设置的 homeAddr。

private void setHomeAddr(String homeAddr) {

this.homeAddr = homeAddr;

}

private String getWorkAddr() {

return workAddr;

}

private void setWorkAddr(String workAddr) {

this.workAddr = workAddr;

}

Student.hbm.xml

<?xml version="1.0" encoding="utf-8"?>

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

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

<!--

Mapping file autogenerated by MyEclipse - Hibernate Tools

-->

<hibernate-mapping>

</id>

</property>

</class>

</hibernate-mapping>

测试代码：

package Search.UserType;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.sql.Blob;

import java.sql.Clob;

import org.hibernate.Hibernate;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

public class Test {

public static void main(String[] args) {

String filePath=System.getProperty("user.dir")+File.separator+"src/Search/UserType"+File.separator+"hibernate.cfg.xml";

File file=new File(filePath);

SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();

Session session=sessionFactory.openSession();

Transaction tx=session.beginTransaction();

AddressType address=new AddressType("home","work");

Student stu=new Student();

stu.setName("tome1");

stu.setAddress(address);

session.save(stu);

tx.commit();

}

转载： http://blog.csdn.net/daryl715/article/details/1927502

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