Case Study

项目中注册了两个PropertyPlaceholderConfigurer，一个是xml中配置的PropertyPlaceholderConfigurer，显示设置ignoreUnresolvablePlaceholders为true（忽略找不到的占位符）；另一个是第三方组件注册的PropertySourcesPlaceholderConfigurer，默认配置。

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="ignoreUnresolvablePlaceholders" value="true"/>
    <property name="ignoreResourceNotFound" value="true"/>
    <property name="properties" ref="prop"/>
    <property name="locations">
        <list>
            <value>classpath:config/*.properties</value>
        </list>
    </property>
</bean>