Implement h2 database to existing spring-boot app

Question

I have simple Spring Boot project, that's contain just two pages. I need to implement H2 database and console to project.

application.properties

spring.datasource.url=jdbc:h2:temdb
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.hibernate.ddl-auto=create
spring.h2.console.enabled=true
spring.h2.console.path=/h2
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

data.sql:

DROP TABLE IF EXISTS billionaires;
CREATE TABLE billionaires (
  id INT AUTO_INCREMENT  PRIMARY KEY,
  first_name VARCHAR(250) NOT NULL,
  last_name VARCHAR(250) NOT NULL,
  career VARCHAR(250) DEFAULT NULL
);
INSERT INTO billionaires (first_name, last_name, career) VALUES
  ('Aliko', 'Dangote', 'Billionaire Industrialist'),
  ('Bill', 'Gates', 'Billionaire Tech Entrepreneur'),
  ('Folrunsho', 'Alakija', 'Billionaire Oil Magnate');

pom.xml

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.0.15.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.0.15.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.freemarker</groupId>
        <artifactId>freemarker</artifactId>
        <version>2.3.29</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>5.0.15.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.thymeleaf</groupId>
        <artifactId>thymeleaf-spring4</artifactId>
        <version>3.0.11.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>2.2.2.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <version>1.4.199</version>
    </dependency>
</dependencies>

When I try to start application and go to http://localhost:8080/h2 to open h2 console, it's 404 error. Server output:

00:25:21.079 [http-nio-8080-exec-6] DEBUG org.springframework.web.servlet.DispatcherServlet - DispatcherServlet with name 'dispatcher' processing GET request for [/h2]
00:25:21.079 [http-nio-8080-exec-6] DEBUG org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Looking up handler method for path /h2
00:25:21.079 [http-nio-8080-exec-6] DEBUG org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Did not find handler method for [/h2]
00:25:21.079 [http-nio-8080-exec-6] WARN org.springframework.web.servlet.PageNotFound - No mapping found for HTTP request with URI [/h2] in DispatcherServlet with name 'dispatcher'
00:25:21.079 [http-nio-8080-exec-6] DEBUG org.springframework.web.servlet.DispatcherServlet - Successfully completed request

What is the reason?

public class WebAppInitializer implements WebApplicationInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        context.register(WebConfig.class);
        context.setServletContext(servletContext);
        ServletRegistration.Dynamic dispatcher = servletContext.addServlet("dispatcher", new DispatcherServlet(context));
        dispatcher.setLoadOnStartup(1);
        dispatcher.addMapping("/");
    }
}

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "ru.rsreu.controller")
public class WebConfig extends SpringStandardDialect {
    @Bean
    @Description("Thymeleaf View Resolver")
    public ThymeleafViewResolver viewResolver() {
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setTemplateEngine(templateEngine());
        viewResolver.setOrder(1);
        return viewResolver;
    }

    @Bean
    @Description("Spring Message Resolver")
    public ResourceBundleMessageSource messageSource() {
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        messageSource.setBasename("user");

        return messageSource;
    }

    @Bean
    public SpringResourceTemplateResolver templateResolver() {
        SpringResourceTemplateResolver templateResolver = new SpringResourceTemplateResolver();
        templateResolver.setPrefix("/WEB-INF/views/");
        templateResolver.setSuffix(".html");
        templateResolver.setCacheable(true);
        return templateResolver;
    }

    @Bean
    public SpringTemplateEngine templateEngine() {
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver());
//        templateEngine.setEnableSpringELCompiler(true);
        return templateEngine;
    }
}

Answer 1

I took your code and updated some things and apparently it worked..

2 changes i made.. spring.datasource.url and dependencies in pom.xml Here is the copy of code that i tried https://github.com/b2p/myTest

application.properties

spring.datasource.url=jdbc:h2:mem:temdb
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.hibernate.ddl-auto=create
spring.h2.console.enabled=true
spring.h2.console.path=/h2
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

pom.xml

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.2.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
....
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <!-- To reload the code when changes made -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.freemarker</groupId>
        <artifactId>freemarker</artifactId>
    </dependency>

    <dependency>
        <groupId>org.thymeleaf</groupId>
        <artifactId>thymeleaf-spring4</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
</dependencies>