Example of how to use the Java IO File class inside a ColdFusion Function to determine the amount of free space.

ex_cfc_GetFreeSpace.cfm

<cffunction name="getFreeSpace" displayname="getFreeSpace" description="Use Java.io.File to return amount of free space in target path" access="public" output="false" returntype="any">
   <cfargument name="path" displayName="path" type="string" hint="File path" required="true" />

   <!--- Create an instance of the Java IO File Class --->
   <cfset var objFile = createObject("java", "java.io.File").init(arguments.path)/>

   <!--- Return the amount of free space --->
   <cfreturn objFile.getFreeSpace() />
</cffunction>  <!--- End: checkFreeSpace() --->