MSSE SENG 5199

autoscale: true theme: Next, 3

Web Services / Spring Boot Intro

Adam Keyser

adam.keyser@gmail.com

Agenda

• Spring Overview
• Spring Boot basics
• Testing
• Spock testing framework

Spring

• One of the popular Java frameworks
• Foundation of Spring Boot
• First release 2002 - 1.0 in 2004
• Maintained by Pivotal Software

Spring - Goals

• Dependency injection
• Decoupling
• Reduces boilerplate
• Testability

Configuration

• Initially xml (Still possible)
• Annotations
• Move to automation of redundancy(Spring Boot)

How it works

1. Classpath scanning
2. Create objects with defined annotations
3. Objects are placed into container (Application Context)
4. Servlet tie in to Application Context (Web Application Context)

Spring Bean lifetime types

• Prototype (new instance)
• Singleton (only one instance)
• When in doubt, Singleton

Spring Bean Stereotypes

• @Component - Generic
• @Repository - Data Access
• @Service - Service Layer
• @Controller - Controller Layer

Popular Spring Add-Ons

• Spring MVC
• Spring Security
• Spring Data
• Spring Rest
• Spring Cloud

Spring Boot

Guiding Philosophy:

• Opinionated patterns to solve common issues
• Start out with a defined pattern of doing things
• Get out of the way quickly when things get more complicated

Convention over configuration

• Framework handles common decision making patterns
  1. Domain classes map to table names by default
  2. Project folder structure constant through projects
  3. Reduce decision making without losing flexibility

Key components

• Spring Boot Starters
• Spring Boot Auto Configurator
• Spring Boot CLI
• Spring Boot Actuator

Spring Boot Isn’t

• Application server
• Specification implementation
• Code generator

Grouping of popular, battle tested frameworks

• Gradle or Maven for building
• Spring for dependency management/configuration
• JPA (Java Persistence API) for Data Access

Included servlet container for running applications

• Embedded in your built JAR
• Tomcat by default, can be swapped out
• Fully tunable and configurable

Spring Boot Internals

• @SpringBootApplication is comprised of:
  1. @ComponentScan
  2. @EnableAutoConfiguartion
  3. @Configuration

Spring Boot starter modules

• Spring provides starter modules for getting up and running quickly

• https://github.com/spring-projects/spring-boot/tree/master/spring-boot-starters

Spring CLI

• Command line interface for managing spring projects
• Powerful: Can create, run, and modify projects
• CLI Documentation

Installing the Spring Boot CLI

> curl -s "https://get.sdkman.io" | bash

> sdk install springboot

Test it out

> spring --version

Demo

@RestController
class HelloController {
	@RequestMapping("/hello/{name}")
	def hello(@PathVariable String name) {
		return [greeting: "Hello, " + name + "!" ]
	}
}

• Run it

> spring run HelloController.groovy

Creating Spring Boot projects

Many ways to start a spring project

• Spring CLI

> spring init --dependencies=web,data-jpa --build gradle --language groovy my-project

• Spring Initializer http://start.spring.io/

Creating Spring Boot projects (IntelliJ)

• IntelliJ IDEA integration (Non-CE)
  • Spring Initializer from new project
• CE IntelliJ Steps
  1. Create project using Initializer
  2. Import project into IntelliJ

Building Spring Boot

Gradle

• Groovy-based build system
• root_project_folder/build.gradle
• http://gradle.org

Cont.

• Repositories: where Gradle looks for dependencies
• Plugins: extensions to Gradle
• Dependencies: libraries your app requires

Configuration files

• gradle.properties For gradle properties
• settings.gradle For other modules within a project

Dependency Management

• Declare the creator, library and version for any dependency
• Uses Maven style dependency management: scope creator:library:version
• example: runtime 'mysql:mysql-connector-java:5.1.29'
• Repositories section provides the ability to add custom dependency sources

Maven Scopes

• compile: default scope, available in all classpaths of project
• provided: expect the JDK or a container to provide it
• runtime: not required at compile time
• test: required for running and compiling tests only
• system: similar to provided, but must be explicitly given. uncommon.

Using Gradle

• Always use ./gradlew “the wrapper”
• Command Options
  1. build (builds and tests the project)
  2. test (only run tests)
  3. clean (remove all class files)
  4. tasks (see all available tasks)
• ex. ./gradlew clean build