@Value不仅可以读取配置文件中的信息 还可以使用SpEL进行运算操作
The first step
文件：musicer.properties
内容：
musicer.age=56
musicer.song=my heart will go on
The second step
Spring文件内容
<bean id="musicerProp" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<property name="locations">
<array>
<value>classpath:musicer.properties</value>
</array>
</property>
</bean>
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PreferencesPlaceholderConfigurer">
<property name="properties" ref="musicerProp"/>
</bean>
The third step
@Value("#{musicerProp['musicer.age']}")
private Integer age;
@Value("#{musicerProp['musicer.song']}")
private String song;
结果打印：
age: 56 Playing my heart will go on :
