自己动手写代码，整合Spring和Hibernate（三）之DAOSupport和DAOTemplate

在《自己动手写代码，整合Spring和Hibernate》系列博文的前两篇中，我们需要为每个DAO类定义一个SessionFactory，需要在DAO的每个方法中获取Session、关闭Session。我们可以写一个公用的DAO类，然后让其他DAO类继承它，实现代码复用。

公用DAO类（抽象类）：

package com.zzj.dao;

import java.io.Serializable;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

public abstract class DAOSupport {

private SessionFactory sessionFactory;

public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
/**
* 保存
* @param t
* @return
*/
protected Serializable save(Object t){
Session session = sessionFactory.openSession();
session.beginTransaction();
Serializable id = session.save(t);
session.getTransaction().commit();
session.close();
return id;
}

protected Object findByID(Class<?> clazz, Serializable id){
Session session = sessionFactory.openSession();
Object t = session.get(clazz, id);
session.close();
return t;
}

}

CustomerDAO类：

package com.zzj.dao;

import com.zzj.entity.Customer;

public class CustomerDAO extends DAOSupport{

/**
* 查询
* @param ID
* @return
*/
public Customer findByID(String ID){
return (Customer) findByID(Customer.class, ID);
}
/**
* 保存
* @param customer
* @return
*/
public String save(Customer customer){
return (String) super.save(customer);
}
}

spring配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<!-- 配置数据源 -->
<!-- <bean name="dataSource" class="com.zzj.base.MyDataSource">
<property name="url">
<value>jdbc:oracle:thin:@localhost:1521:orcl</value>
</property>
<property name="username">
<value>system</value>
</property>
<property name="password">
<value>1223</value>
</property>
<property name="driveClass">
<value>oracle.jdbc.driver.OracleDriver</value>
</property>
</bean> -->
<bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="JdbcUrl">
<value>jdbc:oracle:thin:@localhost:1521:orcl</value>
</property>
<property name="User">
<value>system</value>
</property>
<property name="Password">
<value>1223</value>
</property>
<property name="DriverClass">
<value>oracle.jdbc.driver.OracleDriver</value>
</property>
</bean>

<!-- 配置sessionFactory对象 -->
<bean name="sessionFactory" class="com.zzj.base.MySessionFactory">
<property name="dataSource" ref="dataSource"/>
<property name="dialect">
<value>org.hibernate.dialect.Oracle9Dialect</value>
</property>
<property name="mappings">
<list>
<value>com/zzj/entity/Customer.hbm.xml</value>
</list>
</property>
</bean>
<!-- 配置DAO -->
<bean id="customerDAO" class="com.zzj.dao.CustomerDAO">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
</beans>

以上是使用继承达到了代码的复用，下面使用组合模式达到相同的目的。

公用DAO类（为了区别继承，另外命名，非抽象类）：

package com.zzj.dao;

import java.io.Serializable;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

public class DAOTemplate {
private SessionFactory sessionFactory;

public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
/**
* 保存
* @param t
* @return
*/
protected Serializable save(Object t){
Session session = sessionFactory.openSession();
session.beginTransaction();
Serializable id = session.save(t);
session.getTransaction().commit();
session.close();
return id;
}

protected Object findByID(Class<?> clazz, Serializable id){
Session session = sessionFactory.openSession();
Object t = session.get(clazz, id);
session.close();
return t;
}
}

CustomerDAO类：

package com.zzj.dao;

import com.zzj.entity.Customer;

public class CustomerDAO{
private DAOTemplate daoTemplate;

public void setDaoTemplate(DAOTemplate daoTemplate) {
this.daoTemplate = daoTemplate;
}
/**
* 查询
* @param ID
* @return
*/
public Customer findByID(String ID){
return (Customer) daoTemplate.findByID(Customer.class, ID);
}
/**
* 保存
* @param customer
* @return
*/
public String save(Customer customer){
return (String) daoTemplate.save(customer);
}
}

Spring配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<!-- 配置数据源 -->
<!-- <bean name="dataSource" class="com.zzj.base.MyDataSource">
<property name="url">
<value>jdbc:oracle:thin:@localhost:1521:orcl</value>
</property>
<property name="username">
<value>system</value>
</property>
<property name="password">
<value>1223</value>
</property>
<property name="driveClass">
<value>oracle.jdbc.driver.OracleDriver</value>
</property>
</bean> -->
<bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="JdbcUrl">
<value>jdbc:oracle:thin:@localhost:1521:orcl</value>
</property>
<property name="User">
<value>system</value>
</property>
<property name="Password">
<value>1223</value>
</property>
<property name="DriverClass">
<value>oracle.jdbc.driver.OracleDriver</value>
</property>
</bean>

<!-- 配置sessionFactory对象 -->
<bean name="sessionFactory" class="com.zzj.base.MySessionFactory">
<property name="dataSource" ref="dataSource"/>
<property name="dialect">
<value>org.hibernate.dialect.Oracle9Dialect</value>
</property>
<property name="mappings">
<list>
<value>com/zzj/entity/Customer.hbm.xml</value>
</list>
</property>
</bean>
<!-- 配置DAOTemplate -->
<bean name="daoTemplate" class="com.zzj.dao.DAOTemplate">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
<!-- 配置DAO -->
<bean id="customerDAO" class="com.zzj.dao.CustomerDAO">
<property name="daoTemplate" ref="daoTemplate"></property>
</bean>
</beans>

上面两种方法中，推荐使用组合。 当然了，具体使用哪种方式，就看个人喜好了。

注：每一个具体的DAO类，最终都需要注入一个sessionFactory。