Spring 中 properties 的使用

1.PropertyPlaceholderConfigurer类
它是把属性中的定义的变量(var)替代,spring的配置文件中使用${var}的占位符

beans>
<bean id="configBean" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
           <property name="location"><value>db.properties</value></property>
</bean> 
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <property name="driverClassName"><value>${jdbc.driverClassName}</value></property>
    <property name="url"><value>${jdbc.url}</value></property>
    <property name="username"><value>${jdbc.username}</value></property>
    <property name="password"><value>${jdbc.password}</value></property>
</bean>
</beans>

db.properties文件

<beans>
<bean id="configBean" class="org.springframework.beans.factory.config.PropertyOverrideConfigurer">
           <property name="location"><value>db.properties</value></property>
</bean> 
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <property name="driverClassName"><value>org.hsqldb.jdbcDriver</value></property>
    <property name="url"><value>jdbc:hsqldb:hsql://production:9002</value></property>
    <property name="username"><value>test</value></property>
    <property name="password"><value>123456</value></property>
</bean>
</beans>

db.properties文件

<property name="locations">
<list>
<value>db.properties</value>
<value>db1.properties</value>
</list>
</property>

2)在ApplactionContext中是自动调用BeanFactoryPostProcessor接口的，如果要在BeanFactory中使用，必须手动添加:

= new XmlBeanFactory(new FileSystemResource("beans.xml"));
PropertyPlaceholderConfigurer cfg = new PropertyPlaceholderConfigurer();
cfg.setLocation(new FileSystemResource("jdbc.properties"));
cfg.postProcessBeanFactory(factory);