一个项目中的多个数据源

Question

I am working on a java project in which I have to store some data in a DB or another according to a value in a variable. For the management of databases I use myBatis.

The configuration to the databases:

context.xml

<?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:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    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
   http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

<context:component-scan base-package="com.nombreCompañia.ajax.service" />

<context:annotation-config />

<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
    <property name="jndiName">
        <value>java:comp/env/jdbc/DB1</value>
    </property>
</bean>

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

   <bean id="dataSource_DB2" class="org.springframework.jndi.JndiObjectFactoryBean">
    <property name="jndiName">
        <value>java:comp/env/jdbc/DB2</value>
    </property>
</bean>

<bean id="transactionManager_DB2" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource_DB2" />
</bean>

<tx:annotation-driven />

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource" />
</bean>

<bean id="sqlSessionFactory_DB2" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource_DB2" />
</bean>

<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.iberdrola.persistence.dao" />
    <property name="sqlSessionFactory" ref="sqlSessionFactory" />
</bean>   

I declare the resources in web.xml

<resource-ref id="ResourceRef_5">
    <description>Base de datos 1</description>
    <res-ref-name>jdbc/DB1</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
    <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

<resource-ref id="ResourceRef_0">
    <description>Base de datos 2</description>
    <res-ref-name>jdbc/DB2</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
    <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

I have it this way because for database 1 I have not had any problem and it works correctly for me, so I decided to duplicate the configuration for the second DB, modifying its own configuration.

But how do I change at runtime to use one database or another?

I have searched the internet a lot and cannot find a solution.

I hope your help.

Thank you

Answer 1

Spring's AbstractRoutingDataSource is what you are looking for. It can be used to dynamically change the datasource at runtime. There are lots of examples available on stack overflow and other places on the web.