Java IO - Apache Harmony

[sang]

I am trying to execute a piece of code when a Java application attempts to read from a specifically named file (whether it's through a stream or buffer). I would prefer to implement this in Apache Harmony project found under AOSP's libcore since I am most comfortable with Java. What is the common point of access for Java file reading/writing where I could implement this feature? I am quite new this area so any help would appreciated.