Spring 使用Properties配置文件
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
??? <bean id="propertyConfigurer"
??? ??? class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
??? ??? <property name="location">
??? ??? ??? <value>com/starxing/test/jdbc.properties</value>
??? ??? </property>
??? </bean>
??? <bean id="dataSource"
??? ??? class="org.springframework.jdbc.datasource.DriverManagerDataSource">
??? ??? <property name="url">
??? ??? ??? <value>${database.url}</value>
??? ??? </property>
??? ??? <property name="driverClassName">
??? ??? ??? <value>${database.driver}</value>
??? ??? </property>
??? ??? <property name="username">
??? ??? ??? <value>${database.user}</value>
??? ??? </property>
??? ??? <property name="password">
??? ??? ??? <value>${database.password}</value>
??? ??? </property>

??? </bean>
</beans>

?

当放入多个配置文件时
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>>classpath:system1.properties</value>
<value>>classpath:system2.properties</value>
</list>
</property>
</bean>

还可以这样
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:*.properties</value>
</list>
</property>
</bean>

3.Config.java
package com.starxing.test;

import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.core.io.FileSystemResource;
import org.springframework.jdbc.datasource.DriverManagerDataSource;

public class Config {

??? public static void main(String[] args) {
??? ??? XmlBeanFactory factory = new XmlBeanFactory(new FileSystemResource(
??? ??? ??? ??? "com/starxing/test/conf.xml"));

??? ??? // 如果要在BeanFactory中使用，bean factory post-processor必须手动运行:
??? ??? PropertyPlaceholderConfigurer cfg = new PropertyPlaceholderConfigurer();
??? ??? cfg.setLocation(new FileSystemResource(
??? ??? ??? ??? "com/starxing/test/jdbc.properties"));
??? ??? cfg.postProcessBeanFactory(factory);

??? ??? DriverManagerDataSource dataSource = (DriverManagerDataSource) factory
??? ??? ??? ??? .getBean("dataSource");
??? ??? System.out.println(dataSource.getDriverClassName());

??? ??? // 注意，ApplicationContext能够自动辨认和应用在其上部署的实现了BeanFactoryPostProcessor的bean。这就意味着，当使用ApplicationContext的时候应用PropertyPlaceholderConfigurer会非常的方便。由于这个原因，建议想要使用这个或者其他bean
??? ??? // factory postprocessor的用户使用ApplicationContext代替BeanFactroy。
??? ??? ApplicationContext context = new ClassPathXmlApplicationContext(
??? ??? ??? ??? "com/starxing/test/conf.xml");
??? ??? DriverManagerDataSource dataSource2 = (DriverManagerDataSource) context
??? ??? ??? ??? .getBean("dataSource");
??? ??? System.out.println(dataSource2.getDriverClassName());
??? }

}