How to resolve system variables in spring xml configuration

during Tomcat launch you can specify system variable as ".... -Dmy.value=Hello .... "

but do not forget to put in you Spring configuration following bean:
<bean id="system-properties" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" />

to make this variable resolvable in any other bean configuration like:
...

<entry key="myValue" value="${my.value}" />

..

Spring examples from Spring engineer

Good source of spring example:
https://github.com/joshlong
https://github.com/joshlong/a-walking-tour-of-all-of-springdom

http://marakana.com/s/post/1394/multi_client_development_with_spring_josh_long_video