How to Override Spring-boot application.properties programmatically

I have jdbc property files which I take from external configuration web-service In spring boot in order to set mysql props it's easy as adding those to application.properties:

spring.datasource.url=jdbc:mysql://localhost/mydb
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

How could I override those programticlly in my app?

same goes for Spring-batch props:

database.driver=com.mysql.jdbc.Driver
database.url=jdbc:mysql://localhost/mydv
database.username=root
database.password=root

Thanks, ray.