如何使用属性文件中的值在Spring属性中进行算术运算？

Question

Example use-case: properties file passes in a numeric value in millis, and you want to use it in seconds.

Your .properties file:

jdbc.timeout= 2000

Your applicationContext.xml currently

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">       
   <property name="driverClassName" value="com.mysql.jdbc.Driver" />        
   <property name="url"value="jdbc:mysql://myserver/mydb" />
   <property name="username" value="user" />        
   <property name="password" value="changeme" />        
   <property name="validationQuery" value="SELECT 1;"/>         
   <property name="validationQueryTimeout" value="${jdbc.timeout}" />
</bean>

You want the validationQueryTimeout value to be in seconds, how do you convert it?

Answer 1

如果您使用的是Spring 3.0或更高版本，则可以使用SpEL表达式内的属性，如下所示：

   <property name="validationQueryTimeout" value="#{${jdbc.timeout}/1000}" />