Thanks KeatsPeeks, AbstractRoutingDataSource is a good starter for the solution, and here is a good tutorial on this part.

Mainly the important parts are:

1. define the lookup code

   public class MyRoutingDataSource extends AbstractRoutingDataSource{
       @Override
       protected Object determineCurrentLookupKey() {
           String language = LocaleContextHolder.getLocale().getLanguage();
           System.out.println("Language obtained: "+ language);
           return language;
       }
   }

2. register the multiple datasource

   <bean id="dataSource" class="com.howtodoinjava.controller.MyRoutingDataSource">
      <property name="targetDataSources">
         <map key-type="java.lang.String">
            <entry key="en" value-ref="concreteDataSourceOne"/>
            <entry key="es" value-ref="concreteDataSourceTwo"/>
         </map>
      </property>
      <!-- <property name="defaultTargetDataSource" ref="concreteDataSourceOne"/> -->
   </bean>
   
   <bean id="abstractDataSource" class="org.apache.commons.dbcp.BasicDataSource"
       destroy-method="close"
       p:driverClassName="${jdbc.driverClassName}"
       p:username="${jdbc.username}"
       p:password="${jdbc.password}" />
    
   <bean id="concreteDataSourceOne"
       parent="abstractDataSource"
       p:url="${jdbc.databaseurlOne}"/>
     
    <bean id="concreteDataSourceTwo"
       parent="abstractDataSource"
       p:url="${jdbc.databaseurlTwo}"/>

So after that, the problem is become to:

1. How to load datasource config properties when spring startup and config the corresponding dataSource using the config properties in database.

2. How to use multiple dataSource in spring batch

   Actually when I try to google it, seems this is a most common case, google give the suggestion search words - "spring batch multiple data sources", there are a lots articles, so I choose the answer in

3. How to define the lookup code based on the spring batch jobs(steps)

   Typically this should be a business point, You need define the lookup strategy and can be injected to the com.example.demo.datasource.CustomRoutingDataSource#determineCurrentLookupKey to routing to the dedicated data source.

Limitation

The really interesting is actually it is supports the multiple dataSource, but the db settings cannot store in the DB indeed. The reason is it will get the cycle dependencies issue:

The dependencies of some of the beans in the application context form a cycle:

   batchConfiguration (field private org.springframework.batch.core.configuration.annotation.JobBuilderFactory com.example.demo.batch.BatchConfiguration.jobs)
      ↓
   org.springframework.batch.core.configuration.annotation.SimpleBatchConfiguration (field private java.util.Collection org.springframework.batch.core.configuration.annotation.AbstractBatchConfiguration.dataSources)
┌─────┐
|  routingDataSource defined in class path resource [com/example/demo/datasource/DataSourceConfiguration.class]
↑     ↓
|  targetDataSources defined in class path resource [com/example/demo/datasource/DataSourceConfiguration.class]
↑     ↓
|  myBatchConfigurer (field private java.util.Collection org.springframework.batch.core.configuration.annotation.AbstractBatchConfiguration.dataSources)
└─────┘

So obviously the solution is break the dependency between dataSource and routingDataSource

• Save the DB setting in properties
• Or involve other approach but not in the primary dataSource

See Also

https://scattercode.co.uk/2013/11/18/spring-data-multiple-databases/ https://numberformat.wordpress.com/2013/12/27/hello-world-with-spring-batch-3-0-x-with-pure-annotations/

http://spring.io/guides/gs/batch-processing/

https://stackoverflow.com/questions/25256487/how-to-java-configure-separate-datasources-for-spring-batch-data-and-business-da