SpringBoot

Introduction

• Framework to build microservices
• common non-functional features
• not zero code generation
• not a web or application server
• provides starter projects
• embedded server (incl. in application jar)
• externalized configuration

Concepts

• SpringBoot Autoconfiguration: by scanning the classpath
• Dispatcher Servlet
• SpringBoot Actuator (for monitoring)

Security

adding to pom.xml:

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

and update the project automatically sets up form-based authentication with a generated session cookie generated on the server or basic authentication with a header sent along with every request

• user='user
• pwd=see console output of server start

or set it in application.properties

spring.security.user.name=uwe
spring.security.user.password=uwe

This has to be entered just once.

Configuration

Application Properties

in \<Project>\src\main\resources\application.properties

logging.level.org.springframework = debug

#security configuration see here

#H2 database configuration see here

Implementation

Main Application

see /test1/src/main/java/com/uweheuer/springboot/test1/Test1Application.java/

@SpringBootApplication
public class Test1Application {
  ...
  public static void main(String[] args) {
    SpringApplication.run(Test1Application.class, args);
  }
  ...

Rest Controller

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@CrossOrigin(origins="http://localhost:4200") // avoid cross origin errors in browser
public class HelloWorldController 
{
  // @RequestMapping(method=RequestMethod.GET, path="/hello-world")
  @GetMapping(path="/hello-world")

Resources

• Spring Initializer
• Spring Boot Tutorials by 28Minutes

Examples

Udemy Course

• 
• start eclipse
• File -> Import -> Maven Project

Bookmarks

• 
• start eclipse
• File -> Import -> Maven -> Existing Maven Projects
• select C:\Uwes\eclipse\workspace_2020-12\SpringBoot\bookmarks

Database Configuration

The default is that the datasource url is generated randomly and printed to the console. The default user is 'sa', default password is empty.

• in application.properties

spring.profiles.active=[dev|laptopmysql|raspberry]

• and created in \bookmarks\src\main\resources\ dedicated property files application-[dev|laptopmysql|raspberry].properties

ToDos

• adjust maven build
  • https://riptutorial.com/spring-boot/example/31100/set-the-right-spring-profile-by-building-the-application-automatically--maven-
• build entities
  • https://gist.github.com/michail-nikolaev/3840973
  • https://medium.com/@kthsingh.ms/modeling-a-child-parent-relationship-in-the-same-table-using-jpa-spring-boot-and-representing-it-15e5a6256dab
  • https://vladmihalcea.com/the-best-way-to-map-a-onetomany-association-with-jpa-and-hibernate/
    • The @ManyToOne association uses FetchType.LAZY because, otherwise, we’d fall back to EAGER fetching which is bad for performance.