1. Tomcat数据源配置还能用吗？如果是这样，它如何知道要使用哪个配置文件？
您可以使用 Tomcat 数据源配置，但是数据源定义与 Spring 或 Spring 配置文件无关。如果您使用的是 JNDI 方法，那么您可能定义了多个数据源，并且可以通过配置文件属性指定在您的应用程序中使用的数据源，但实际定义与 Spring 无关。
或者，您可以使用非 JNDI 数据源，即在 Spring 中配置并可能使用配置文件。
2. 多环境如何配置persistence.xml？jdbc 连接道具是否应该在 persistence.xml 中
不，在使用 Spring 时，您只需要一个最小的 persistence.xml，或者根本不需要。
3.如何在不重新编译的情况下设置活动配置文件？
你不能
以下是启动和运行非 JNDI 数据源所需的全部内容。
示例 Spring 配置（非 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>
示例 Spring 数据源定义
<?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>
示例弹簧配置文件定义：
<?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>
最小持久性.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>
示例配置文件属性文件：
#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