Spring container has features that it can auto detect your initialization and Destroy method if you follow same coding convention in project.

Java Code:
<beans default-init-method="init">
<bean id="sampleService" class="org.abc.DefaultSample">
<property name="samplename" ref="sampleName" />
Destroy method callbacks are also similarly use the 'default-destroy-method'.
Attribute on the top-level <beans/> element. So Spring IoC container will recognize a method called 'init' on beans as being the initialization method callback, and when a bean is being created and assembled, if the bean's class has such a method, it will be invoked at the appropriate time.