Hi I have a open source PostGIS they provided plugins to connect Geo server . like I have Orient db that doesn't supported By geo server so I want write plugins how can write is there any way .
You need to implement a GeoTools datastore for your database. There is a tutorial that shows you how to create a new datastore. Once created you drop the jar into the GeoServer WEB-INF/lib folder and restart GeoServer which will use the SPI mechanism to pick up the new store.