POI-OpenXML4J - Java API To Access Office Open XML documents
OpenXML4J is the POI Project's pure Java implementation of the Open Packaging Conventions (OPC) defined in ECMA-376.
Every OpenXML file comprises a collection of byte streams called parts, combined into a container called a package. POI OpenXML4J provides a physical implementation of the OPC that uses the Zip file format.
OpenXML4J was originally developed by openxml4j.org, and was contributed to Apache POI in 2008. The original code is available at https://sourceforge.net/projects/openxml4j/. Thanks to the support and guidance of Julien Chable