I think you can get it through DBC file.
and you can get the DBC file path from about this page -> java System properties ->DBC File.
Yes, You can get JDBC connection from DBC file: $INST_TOP/appl/fnd/secure/<SID>.dbc and also from Context file: $INST_TOP/appl/admin/<SID>_<Server>.xml (look for string s_apps_jdbc_connect_descriptor)
You can also use OAM -> Autoconfig screen to find s_apps_jdbc_connect_descriptor from Application Context file.
Have you got the JDBC connection Url?
From the Apps Node, read file <SID>.dbc in '$INST_TOP/appl/fnd/12.0.0/secure' directory using 'cat' command. There you will find APPS_JDBC_URL.