Qfyilyi

I have been using a real simple H2 DB on a file. I had my setup like this:

Class.forName("org.h2.Driver");

Connection conn = DriverManager.getConnection("jdbc:h2:"+dbFileName);

Statement stat = conn.createStatement();

and on application startup, I would simply do:

File dbFile = new File("~/mydb.db");

if(!dbFile.exists()) {

   String sql = -create my table here, etc...

}

But I am now trying to do this in a "correct" Spring Boot way. So I have my application.properties file to contain this:

# H2

spring.h2.console.enabled=true

spring.h2.console.path=/h2

spring.datasource.url=jdbc:h2:file:~/mydb.db

spring.datasource.username=sa

spring.datasource.password=

spring.datasource.driver-class-name=org.h2.Driver

And I am trying to use the JdbcTemplate / Dao way of doing things. But I need to check if the DB is there at startup. So I want to do my previous check in the Application classes event listener for ApplicationReadyEvent. But how do I get a reference to the datasource url? I had is a a configuration property before and was automatically loaded, and I could still do that, but it would be in to places and that would be bad.

So what's the essayist / correct way to ensure this DB file is there when the application starts up. (and I want this in a JDBC way, no JPA please)

You can use ApplicationListener then parse the spring.datasource.url value:

import java.io.File;



import org.springframework.beans.factory.annotation.Value;

import org.springframework.boot.context.event.ApplicationStartedEvent;

import org.springframework.context.ApplicationListener;

import org.springframework.stereotype.Component;



@Component

public class MyApplicationListener implements ApplicationListener<ApplicationStartedEvent> {



    @Value("${spring.datasource.url}")

    private String databaseUrl;



    @Override

    public void onApplicationEvent(ApplicationStartedEvent event) {

        System.out.println("Application started");

        String path = databaseUrl.replace("jdbc:h2:file:", "");

        System.out.println(path);

        File dbFile = new File(path);

        if (!dbFile.exists()) {

            String sql = "etc";

        }

    }



}