1. Create Self Signed SSL Certificate

   keytool -genkeypair -alias filenameAlias -keyalg RSA -keysize 2048 -storetype PKCS12 -keystore filename.p12 -validity 3650
   

   And use below code to view certificate details.

   keytool -list -keystore  filename.p12
   

2. Enabling HTTPS in Spring Boot application.propreties

   # The format used for the keystore. for JKS, set it as JKS
     server.ssl.key-store-type=PKCS12
   # The path to the keystore containing the certificate
     server.ssl.key-store=classpath:keystore/javadevjournal.p12
   # The password used to generate the certificate
   server.ssl.key-store-password=use the same password which we added during certificate creation
   # The alias mapped to the certificate
     server.ssl.key-alias=javadevjournal
   # Run Spring Boot on HTTPS only, default 443 like no https 80 port
   server.port=8443
   

Note that you need copy filename.p12 to src/main/resources/keystore folder