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.

Testing

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

This integrates the frameworks JUnit, Hamcrest, Mockito,

Configuration

Application Properties

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

logging.level.org.springframework = debug

#security configuration see here

#H2 database configuration see here

#logging configuration see here

Logging

A good description is here. The default log output is

<DATE>  <LOG_LEVEL> <PROCESS_ID> --- <THREAD_NAME> [<LOGGER_NAME>] <LOG_MESSAGE>

To implement logging

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
final static Logger logger = LoggerFactory.getLogger(BookmarksRestController.class);  // is the LOGGER_NAME
BookmarksRestController.logger.trace(...

The general configuration in application.properties:

# a selection of core loggers (embedded container, Hibernate, and Spring Boot) are configured to output more information
debug=true 

# enables trace logging for a selection of core loggers (embedded container, Hibernate schema generation, and the whole Spring portfolio)
trace=true 

logging.file.name=./log/bookmarks.log
logging.logback.rollingpolicy.max-history=5
# double backslash quote for policy and logback
logging.pattern.file=%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{1}.%M{}\\(\\) - %L: %m%n 
logging.pattern.console=%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{1}.%M{}\\(\\) - %L: %m%n

The specific configuration can be set according to package/class hierachy:

logging.level.<PACKAGE_NAMEn>=<LEVEL>
logging.level.<PACKAGE_NAME1.PACKAGE_NAME2>=<LEVEL>
logging.level.<PACKAGE_NAME1.PACKAGE_NAME2.CLASSNAME>=<LEVEL>
// e.g.
logging.level.com.uweheuer=INFO
logging.level.com.uweheuer.bookmarks=TRACE
logging.level.com.uweheuer.bookmarks.entities=INFO

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);
  }
  ...

@SpringBootApplication

is a convience annotation that adds @Configuration, @EnableAutoConfiguration, @EnableWebMvc and @ComponentScan.

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")
  @JsonView(MenuView.NodeView.class) // tells Jackson to propagate the view class to the entities for json-fication the return value
                                     // the same annotation has to be used at attributes in the JPA entities, which should be used for this view
  public <METHOD>() {
    ...
  }

@RequestMapping

@RequestMapping("/") // by default it maps HTTP operations

Integration Test

@SpringBootTest
class BookmarksApplicationTests {

  @Test
  void contextLoads() {
  }
}

Resources

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

H2 Database Configuration

see application-dev.properties

# to make the h2 database url constant, otherwise it is a random url
spring.datasource.url=jdbc:h2:mem:bookmarksdb
# user and password for H2 console
spring.datasource.username=uwe
spring.datasource.password=uwe

Test Data for Startup

in <PROJECT_DIR>/src/main/resources/data.sql

Links

see My Bookmarks -> Web-Präsenz -> localhost -> SpringBoot -> Bookmarks

ToDos

JSON rest APIs
- @JsonIdentityInfo
- @JSonView
adjust maven build
- https://riptutorial.com/spring-boot/example/31100/set-the-right-spring-profile-by-building-the-application-automatically--maven-
build entities
- The @ManyToOne association uses FetchType.LAZY because, otherwise, we’d fall back to EAGER fetching which is bad for performance.
https://thorben-janssen.com/ultimate-guide-derived-queries-with-spring-data-jpa/ Query Documentation]
- Sorted Lists