[OSGi] Eclipse RCP环境中定义MyBatis与Spring的整合之DAO与申明式事务

OSGi程序的开发与基于Java的N-Tier的程序的开发有着千丝万缕的联系，过去，我们人为的将程序从结构上进行划分，这样职责分明，也符合面向对象设计的高内聚低耦合的思想。而OSGi本身就是基于组件的开发，各个组件之间的依赖通过Import-Package和Export-Package来实现，而且通过组件间的申明式Service(服务)完成组件之间的协作，OSGi与生俱来就是基于接口开发的高内聚且松散耦合的，与Spring可以说天生就是一对~

最近有一个小小的项目使用到了RCP，MyBatis和Spring Dynamic Module，首先，整个程序中有关的组件依赖如下图所示：



注：所有Bundle都会依赖Domain Bundle

DAO Bundle：定义了MyBatis中Mapper Interface，只有mapper接口的定义，例如CustomerMapper

DAOImpl Bundle：定义了映射XML文件，Spring的Bean Definition中包含了数据库连接，Mapper Bean和事务管理器的申明

Service Bundle：定义了服务接口，例如BusinessService定义了addCustomer, updateCustomer, deleteCustomer, getCustomer等业务方法

ServiceImpl Bundle：服务的实现，Spring的Bean Definition中包含了服务的申明和Export。BusinessServiceImpl会使用CustomerMapper来实现业务逻辑。

1. DAOImpl Bundle的Application Context例子:

<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> 
<!-- Property Place Holder Configuration -->
<context:property-placeholder location="classpath:configuration.properties"/>

<!-- Data Source Configuration -->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="${jdbc.driverClassName}"/>
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<property name="initialSize" value="${jdbc.initialSize}" />
<property name="maxActive" value="${jdbc.maxActive}" />
<property name="maxWait" value="${jdbc.maxWait}" />
</bean>

 <bean id="transactionManager"  class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean> 

<!-- SQL Session Factory Configuration -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="configLocation" value="classpath:fugaobatis.xml" />
</bean>

<!-- Mapper Bean -->
<bean id="customerMapper" scope="bundle" class="org.mybatis.spring.mapper.MapperFactoryBean">
<property name="mapperInterface" value="org.sean.fugao.data.persistence.CustomerMapper"/>
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>
</beans>

2. DAOImpl Bundle必须将Mapper和TransactionManager Export为Bundle Service，那么在ServiceImpl中才能使用Mapper访问数据库，事务也才能定义在ServiceImpl的方法调用之上。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:osgi="http://www.springframework.org/schema/osgi"
xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi.xsd">

<osgi:service ref="transactionManager" interface="org.springframework.transaction.PlatformTransactionManager" />

<bean id="customerMapperExporter" class="org.springframework.osgi.service.exporter.support.OsgiServiceFactoryBean">
<property name="target">
<ref bean="customerMapper"/>
</property>
<property name="interfaces">
<list>
<value>org.sean.fugao.data.persistence.CustomerMapper</value>
</list>
</property>
</bean>
</beans>

3. ServiceImpl Bundle会引用DaoImpl Bundle中定义的transaction Manager和customer mapper(通过osgi:reference标签和OsgiServiceProxyFactoryBean来实现)

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:osgi="http://www.springframework.org/schema/osgi"
xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi.xsd">

<osgi:reference id="transactionManager" interface="org.springframework.transaction.PlatformTransactionManager"/>

<bean id="customerMapperService" class="org.springframework.osgi.service.importer.support.OsgiServiceProxyFactoryBean">
<property name="beanName" value="customerMapper"/>
<property name="interfaces">
<list>
<value>org.sean.fugao.data.persistence.CustomerMapper</value>
</list>
</property>
</bean>
</beans>

4. ServiceImpl Bundle中Service的定义和Spring申明式事务

<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> 
<bean id="abstractService" class="org.sean.fugao.data.service.impl.AbstractService" abstract="true">
<property name="customerMapper" ref="customerMapperService" />
</bean>

<bean id="businessServiceTarget" class="org.sean.fugao.data.service.impl.FugaoServiceImpl" parent="abstractService"/>

<bean id="txProxyTemplate" abstract="true" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
<property name="transactionManager" ref="transactionManager"/>
<property name="transactionAttributes">
<props>
<prop key="save*">PROPAGATION_REQUIRED</prop>
　　　　 <prop key="add*">PROPAGATION_REQUIRED</prop>
　　　　 <prop key="update*">PROPAGATION_REQUIRED</prop>
　　　　 <prop key="remove*">PROPAGATION_REQUIRED</prop>
　　　　 <prop key="get*">PROPAGATION_REQUIRED, readOnly</prop>
</props>
</property>
</bean>

<bean id="businessService" parent="txProxyTemplate">
<property name="target" ref="businessServiceTarget"/>
</bean>
</beans>

5. 同样，也可以在ServiceImple中将businessService Export为bundle service供其他bundle引用

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:osgi="http://www.springframework.org/schema/osgi"
xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi.xsd">

<osgi:service id="fugaoServiceExporter" ref="businessService" interface="org.sean.fugao.data.service.FugaoService"/>
</beans>