Specify datasource on tomcat(app server)

I learned that from my coworker Michael. He's really helpful. I learned a lot from him in half an hour.

In our company, we have several portlets in Liferay portal which we can add them into our pages. Some of them deal with database. Those portlets need to specify DataSource. Previously, I just define the bean in springconfiguration.xml. But it's not a good way. In case our datasource has changed, we have to go into every project and change every xml file. 

If we define the datasource in one place, we only need to change on place and restart tomcat. It's pretty neat.

springconfiguration.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:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:util="http://www.springframework.org/schema/util"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xsi:schemaLocation="
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context-3.1.xsd      
    http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.1.xsd      
    http://www.springframework.org/schema/jdbc 
    http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd      
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
    http://www.springframework.org/schema/jee 
    http://www.springframework.org/schema/jee/spring-jee-3.1.xsd
    http://www.springframework.org/schema/util 
    http://www.springframework.org/schema/util/spring-util-3.1.xsd">
    
    
    <jee:jndi-lookup id="myDataSource" jndi-name="jdbc/mydatasource"/>
//...more

tomcat-7.0.25\conf\context.xml

     <Resource name="jdbc/mydatasource" 
        auth="Container" 
        type="javax.sql.DataSource"
        driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver" 
        url="jdbc:sqlserver://IP:port;databaseName=***"
        username="***" 
        password="***"
        maxActive="20" 
 />

Then all your application in the same server, we can use the same datasource.