1. Can you still use the Tomcat datasource configuration? If so how does it know which profile to use?
You can use the Tomcat datasourse configuration however the datasource definition will have nothing to do with Spring or Spring profiles. If you are using JNDI approach then you may have multiple datasources defined and can specify that one used in you application via profile properties however the actual definition will have nothing to do with Spring.
Or, you can use a non-JNDI datasource i.e configured in Spring and perhaps using profiles.
2. How do you configure persistence.xml for multiple environments? Should the jdbc connection props even be in persistence.xml
No, you only need a minimal persistence.xml when using Spring or perhaps not at all.
3. How do you set the active profile without recompiling?
You can't
The following is all you need to get up and running with a non-JNDI datasource.
Example Spring Configuration (non-JNDI):
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd">
<jpa:repositories base-package="uk.co.certait.spring.data.repository" />
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="jpaVendorAdapter" ref="jpaAdapter"></property>
<property name="persistenceUnitName" value="persistenceUnit" />
<property name="dataSource" ref="dataSource" />
<property name="jpaProperties">
<props>
<prop key="hibernate.hbm2ddl.auto">${hibernate.ddl.auto}</prop>
<prop key="hibernate.dialect">${hibernate.dialect}</prop>
<prop key="hibernate.show_sql">${hibernate.show.sql}</prop>
<prop key="hibernate.format_sql">true</prop>
<prop key="hibernate.cache.use_second_level_cache">${hibernate.enable.cache}</prop>
<prop key="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</prop>
</props>
</property>
</bean>
<bean id="jpaAdapter"
class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
<bean class="org.springframework.orm.jpa.JpaTransactionManager"
id="transactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
</beans>
Example Spring Datasource Definition
<?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-3.1.xsd">
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName">
<value>${database.driver}</value>
</property>
<property name="url">
<value>${database.url}</value>
</property>
<property name="username">
<value>${database.username}</value>
</property>
<property name="password">
<value>${database.password}</value>
</property>
</bean>
</beans>
Example Spring Profile Definition:
<?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-3.1.xsd">
<beans profile="default">
<bean id="applicationPropertiesPlaceholder"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:profiles/hsqldb.profile.properties</value>
</list>
</property>
</bean>
</beans>
<beans profile="hsqldb">
<bean id="applicationPropertiesPlaceholder"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:profiles/hsqldb.profile.properties</value>
</list>
</property>
</bean>
</beans>
<beans profile="mysql">
<bean id="applicationPropertiesPlaceholder"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:profiles/mysql.profile.properties</value>
</list>
</property>
</bean>
</beans>
<beans profile="mssql">
<bean id="applicationPropertiesPlaceholder"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:profiles/mssql.profile.properties</value>
</list>
</property>
</bean>
</beans>
</beans>
Minimal Persisteance.XML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="persistenceUnit"
transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.ImprovedNamingStrategy" />
<property name="hibernate.connection.charSet" value="UTF-8" />
</properties>
</persistence-unit>
</persistence>
Sample Profile Properties File:
#MySQL
#database.url=jdbc:mysql://localhost:3306/test
database.url=jdbc:log4jdbc:mysql://localhost:3306/test
#database.driver=com.mysql.jdbc.Driver
database.driver=net.sf.log4jdbc.DriverSpy
database.username=root
database.password=password
hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
hibernate.show.sql=false
hibernate.ddl.auto=create
hibernate.enable.cache=false
