spring中加载properties文件

<bean id="propertyConfigurer"
		class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
	<property name="location">
		<value>classpath:ldap.properties</value>
	</property>
</bean>

<bean id="contextSource" class="org.springframework.ldap.core.support.LdapContextSource">
	<property name="url" value="${url}" />
	<property name="base" value="${base}" />
	<property name="userDn" value="${userDn}" />
	<property name="password" value="${password}" />
</bean>

ldap.properties文件：

url=ldap://61.xxx.xxx.xxx:389
base=o=mycom.com,c=cn
userDn=cn=root,o=mycom.com,c=cn
password=secret