If I have written my own DataSourceFactory, then how can Geo Server recognize my dataSourceFactory? As I know that if we register with org.geotools.data.DataStoreFactorySpi then automatically Geo Server recognizes our data source. But I don't know how to register with Geo Server. I am planning to create a Java project (mvn).
If you are implementing a store you can follow the tutorial at: http://docs.geotools.org/stable/userguide/tutorial/datastore/index.html (GeoServer expects to find GeoTools data stores).
In particular, the answer to your specific question is at the bottom of this page, you have to register it in a META-INF/services/org.geotools.data.DataStoreFactorySpi file:
http://docs.geotools.org/stable/userguide/tutorial/datastore/source.html