To access application:
http://localhost:8081/SpringBoot_Form/forms
http://localhost:9090/SpringBoot_Form/dropDown

To add run time argument, such as a new server port number, for the .exe create a .ini fie:
The ini file's name must correspond to the exe file (myapp.exe: myapp.l4j.ini)

Windows command line to display Java processes:
> jpf

Windows command line to kill a Java process:
> taskkill /F /PID <ProcessID>

Use http://localhost:8081/SpringBoot_Form/h2-console to access H2 console in browser:
Driver Class: org.h2.Driver
JDBC URL: jdbc:h2:file:./mydemodb
User Name: sa
Password: sa

Or use DBeaver as an universal SQL client to access H2 database, but need to kill the exe process first.

Get the Running Port in Spring Boot:
https://www.baeldung.com/spring-boot-running-port

Spring Boot AJAX Get and Post Examples with jQuery: 
https://www.youtube.com/watch?v=8IcTBJ7D0Ek