browser executing local file

Tech skills required: Java or another programming language that can access the user’s file system from a web browser, specifically Chrome. Platform: Chrome browser running on Windows XP, Vista, or 7 applet (Java?) must be allowed to open from Chrome web browser. We have an executable that can open a cash drawer connected to the user’s computer by usb. We need an app (Java?) that can be run from the browser that can access the user’s file system and run the executable. The app must be written in a way that it can be executed on demand from a web page using javascript (or PHP). The user should not be required to click a button to execute the app. The app should first check for the presence of the attached [login to view URL] file in a specified directory (C:\BIT\CASH\). If not present, it should return a message. If the file is present, the app should execute the file. The app will likely need to be signed and allow the user to be warned that the app will access the file system and be given the option to run or cancel.