How to build a java web application using SAP platform and HANA database?

You would require to change the connection.properties file of your local Tomcat Server (Server > Java Web Tomcat 8 Server-config/config_master/connection_data), to point to the HANA database.

Here are the usual parameters that need to be configured for HANA database

javax.persistence.jdbc.driver=com.sap.db.jdbc.Driver
javax.persistence.jdbc.url=jdbc:sap://<host>:<port>/?reconnect=true&autocommit=false
javax.persistence.jdbc.user=db-user
javax.persistence.jdbc.password=db-pass
eclipselink.target-database=HANA