Annotation-based Dependency Injection using ColdSpring

ColdSpring is by far the most essential tool I need for building ColdFusion applications. However, I'm not a huge fan of writing a ton of XML and I'm certainly not a fan of writing a lot of getters and setters inside my components.

To help ease that pain, I borrowed a feature from Model-Glue 3 and extended ColdSpring to create the "beans" scope.

Little did I realize ColdSpring can already handle a lot of what I wanted to do without having to modify ColdSpring itself simply by creating a factory post processor. To automatically inject the "beans" scope into my ColdSpring-managed beans, I created the following BeansScopeFactoryPostProcessor.cfc:

<cfcomponent>

 <cffunction name="postProcessBeanFactory" access="public" returntype="void">

  <cfset var local = {} />

  <cfset local.beanDefs = getConcreteBeanClasses() />

  <cfloop collection="#local.beanDefs#" item="local.beanName">

   <cfset local.beanList = getBeanScopeList(local.beanDefs[local.beanName]) />

   <cfif local.beanList neq "">

    <cfset local.bean = getBeanFactory().getBean(local.beanName) />

    <cfset injectBeansScope(local.bean,local.beanList) />

   </cfif>

  </cfloop>

 </cffunction>

 <cffunction name="getConcreteBeanClasses" access="private" returntype="struct">

  <cfset var local = {} />

  <cfset local.classes = {} />

  <cfset local.beanDefs = getBeanFactory().getBeanDefinitionList() />

  <cfloop collection="#local.beanDefs#" item="local.beanName">

   <cfif not local.beanDefs[local.beanName].isAbstract()>
    <cfset local.classes[local.beanName] = local.beanDefs[local.beanName].getBeanClass() />
   </cfif>

  </cfloop>

  <cfreturn local.classes />

 </cffunction>

 <cffunction name="injectBeansScope" access="private" returntype="void">
  <cfargument name="bean" required="true" />
  <cfargument name="beanList" required="true" />

  <cfset var local = {} />

  <cfif isCFC(arguments.bean)>

   <cfset local.beans = {} />

   <cfloop list="#arguments.beanList#" index="local.beanName">
    <cfset local.beans[local.beanName] = getBeanFactory().getBean(local.beanName) />
   </cfloop>

   <cfset arguments.bean.__setVariable = variables.__setVariable />

   <cfset arguments.bean.__setVariable("beans",local.beans) />

   <cfset StructDelete(arguments.bean,"__setVariable") />

  </cfif>

 </cffunction>

 <cffunction name="getBeanScopeList" access="private" returntype="string">
  <cfargument name="bean" required="true" />

  <cfset var local = {} />

  <cfset local.metaData = getComponentMetaData(arguments.bean) />

  <cfset local.beanList = "" />

  <cfif StructKeyExists(local.metaData,"beans")>

   <cfloop list="#local.metaData.beans#" index="local.beanName">
    <cfset local.beanList = ListAppend(local.beanList,local.beanName) />
   </cfloop>

  </cfif>

  <cfset local.extendedMetaData = local.metaData />

  <cfloop condition="StructKeyExists(local.extendedMetaData,'extends')">

   <cfif StructKeyExists(local.extendedMetaData,"beans")>

    <cfloop list="#local.extendedMetaData.beans#" index="local.beanName">

     <cfif not listFindNoCase(local.beanList,local.beanName)>
      <cfset local.beanList = ListAppend(local.beanList,local.beanName) />
     </cfif>

    </cfloop>

   </cfif>

   <cfset local.extendedMetaData = local.extendedMetaData.extends />

  </cfloop>

  <cfreturn local.beanList />

 </cffunction>

 <cffunction name="setBeanFactory" access="public" returntype="void">
  <cfargument name="beanFactory" required="true" type="coldspring.beans.BeanFactory" />

  <cfset variables.beanFactory = arguments.beanFactory />

 </cffunction>

 <cffunction name="getBeanFactory" access="private" returntype="any">

  <cfreturn variables.beanFactory />

 </cffunction>

 <cffunction name="__setVariable" access="public" returntype="void">
  <cfargument name="key" required="true" />
  <cfargument name="value" required="true" />

  <cfset variables[arguments.key] = arguments.value />

 </cffunction>

 <cffunction name="isCFC" access="private" returntype="boolean">
  <cfargument name="object" required="true" />

  <cfset var metaData = getMetaData(arguments.object) />

  <cfreturn isObject(arguments.object) and structKeyExists(metaData,"type") and metaData.type eq "component" />

 </cffunction>

</cfcomponent>

Long story short, it looks at all the beans defined in ColdSpring, checks their metadata for a "beans" attribute inside the cfcomponent tag, and automatically injects the requested beans into the component inside a variables.beans struct.

To get ColdSpring to process my beans, I define the factory post processor as such:

<bean id="beanInjector" class="test.BeansScopeFactoryPostProcessor" factory-post-processor="true" />

For those unaware of how factory post-processors work, ColdSpring will look for any beans where factory-post-processor="true" and automatically call postProcessBeanFactory() on those beans once the bean factory has been initialized.

To keep the code relatively small in this post, I removed any comments. Hopefully it's still somewhat straight-forward and easy to follow.