You can use JNDI for this. First you need to know the DN of the target object and the name of the attribute where the CSV file will be stored. Then you just call DirContext.modifyAttributes() with the appropriate parameters. You will probably need the contents of the CSV file as a byte, although why anybody would want to store a CSV file in AD is a mystery to me. No doubt I am uninformed on the point.
There was/is a utility inlcuded in Windows called CSVDE that in fact used a CSV delimited file format to access AD. To be honest I can't remember if it only supported exporting objects from AD, or whether it also supported import operations as well.