Spring Boot - By Jeevesh Pandey

• What and Why?• Key features of Spring boot.• Prototyping using CLI.• Working with Spring Boot with gradle.• Packaging Executable Jars / Fat jars • Managing profiles • Binding Properties - Configurations• Using Spring data libraries • Presentation layer(A glimpse)• Miscellaneous

Agenda

• Spring-boot provides a quick way to create a Spring based application from dependency management to convention over configuration.

• It’s not a replacement for Spring framework but it presents a small surface area for users to approach and extract value from the rest of Spring.

• To provide a range of non-functional features that are common to large classes of projects (e.g. embedded servers, security, metrics, health checks, externalized configuration)

• Grails 3.0 will be based on Spring Boot.

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What and Why ?

• Stand-alone Spring applications with negligible efforts.• No code generation and no requirement for XML Config• Automatic configuration by creating sensible defaults• Provides Starter dependencies / Starter POMs.• Structure your code as you like• Supports Gradle and Maven• Provides common non-functional production ready features for a

“Real” application such as – security– metrics– health checks– externalised configuration

Key Features

• Quickest way to get a spring app off the ground• Allows you to run groovy scripts without much boilerplate code• Not recommended for production

Install using SDK$ sdk install springboot

Running groovy scripts$ spring run app.groovy$ spring jar test.jar app.groovy

Rapid Prototyping : Spring CLI

@Controllerclass Example {

@RequestMapping("/") @ResponseBody

public String helloWorld() {"Hello Spring boot audience!!!"

}}

Getting Started Quickly using CLI

// import org.springframework.web.bind.annotation.Controller// other imports ...// @Grab("org.springframework.boot:spring-boot-starter-web:0.5.0")

// @EnableAutoConfiguration@Controllerclass Example { @RequestMapping("/") @ResponseBody public String hello() { return "Hello World!"; }

// public static void main(String[] args) {// SpringApplication.run(Example.class, args);// }}

What Just Happened ?

One-stop-shop for all the Spring and related technologyA set of convenient dependency descriptorsContain a lot of the dependencies that you need to get a project up and

running quicklyAll starters follow a similar naming pattern;

spring-boot-starter-*Examples

spring-boot-starter-web(tomcat and spring mvc dependencies)– spring-boot-starter-actuator– spring-boot-starter-security– spring-boot-starter-data-rest– spring-boot-starter-amqp– spring-boot-starter-data-jpa– spring-boot-starter-data-elasticsearch– spring-boot-starter-data-mongodb

Starter POMs

@Grab('spring-boot-starter-security')@Grab('spring-boot-starter-actuator')@Grab('spring-boot-starter-jetty')@Controllerclass Example {

@RequestMapping("/")@ResponseBodypublic String helloWorld() {

return "Hello Audience!!!"}

}

//security.user.name//security.user.password

//actuator endpoints: /beans, /health, /mappings, /metrics etc.

Demo : Starter POM

Spring Initializer

● Using Intellij Idea Spring initializer● Using start.spring.io https://start.spring.io/

apply plugin: 'groovy'apply plugin: 'java'apply plugin: 'idea'apply plugin: 'spring-boot'

buildscript { repositories { mavenCentral()} dependencies { classpath("org.springframework.boot:spring-boot-gradle-plugin:1.1.8.RELEASE") classpath 'org.springframework:springloaded:1.2.0.RELEASE' }}

repositories { mavenCentral() }

dependencies { compile 'org.codehaus.groovy:groovy-all' compile 'org.springframework.boot:spring-boot-starter-web'}

Generated Gradle Build Script

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$ gradle build$ java -jar build/libs/mymodule-0.0.1-SNAPSHOT.jar

Build and Deploy

• Put application.properties/application.yml somewhere in classpath• Easy one: src/main/resources folder

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app: name: Springboot+Config+Yml+Demo version: 1.0.0server: port: 8080settings: counter: 1---spring: profiles: developmentserver: port: 9001

app.name=Springboot+Config+Demoapp.version=1.0.0server.port=8080settings.counter=1

application.properties

app.name=Springboot+Config+Demoapp.version=1.0.0server.port=8080

application-dev.properties

Environments and Profiles

application.properties

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export SPRING_PROFILES_ACTIVE=developmentexport SERVER_PORT=8090gradle bootRunjava -jar build/libs/demo-1.0.0.jar

java -jar -Dspring.profiles.active=development build/libs/dem-1.0.0.jarjava -jar -Dserver.port=8090 build/libs/demo-1.0.0.jar

OS env variable

with a -D argument (JVM Argument)

Examples

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import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.stereotype.Component;@Component@ConfigurationProperties(prefix = "app")public class AppInfo { private String name; private String version;}

Using ConfigurationProperties annotation

import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Component;@Componentpublic class AppConfig { @Value('${app.name}') private String appName;

@Value('${server.port}') private Integer port;}

Using Value annotation

Binding Properties

Using Spring data:MySQL• Add dependency

• Configure database URL

compile 'mysql:mysql-connector-java:5.1.6'compile 'org.springframework.boot:spring-boot-starter-jdbc'compile 'org.springframework.boot:spring-boot-starter-data-jpa'

spring.datasource.url= jdbc:mysql://localhost/springbootspring.datasource.username=rootspring.datasource.password=rootspring.datasource.driverClassName=com.mysql.jdbc.Driverspring.jpa.hibernate.ddl-auto=create-drop

• • Entity class

•

import javax.persistence.*;

@Entitypublic class User{ @Id private Long id; private String name;

//Getter and Setter }

Using Spring data:MySQL

• • Add repository interface import org.springframework.data.jpa.repository.JpaRepository; public interface UserRepository extends JpaRepository<User, Long>{

User findByName(String name); }

• Usage@Autowired private UserRepository userRepository;

userRepository.findByName();userRepository.save();userRepository.findAll();

For more : http://www.oracle.com/technetwork/middleware/ias/toplink-jpa-annotations-096251.html

View templates libraries(A Glimpse)

• JSP/JSTL• Thymeleaf• Freemarker• Velocity• Tiles• GSP• Groovy Template Engine

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Logging

$ java -jar myapp.jar --debug

logging.level.*: DEBUG_LEVEL

E.g.

logging.level.intellimeet: ERROR

Actuator for Production

ID Description Sensitive

autoconfig Displays an auto-configuration report showing all auto- configuration candidates and the reason why they ‘were’ or ‘were not’ applied.

true

beans Displays a complete list of all the Spring beans in your application. true

configprops Displays a collated list of all @ConfigurationProperties. true

dump Performs a thread dump. true

env Exposes properties from Spring’s ConfigurableEnvironment. true

health Shows application health information (a simple ‘status’ when accessed over an unauthenticated connection or full message details when authenticated).

false

info Displays arbitrary application info. false

metrics Shows ‘metrics’ information for the current application. true

mappings Displays a collated list of all @RequestMapping paths. true

shutdown Allows the application to be gracefully shutdown (not enabled by default). true

trace Displays trace information (by default the last few HTTP requests). true

Miscellaneous

- Enabling Disabling the Banner

- Changing the Banner

(http://www.kammerl.de/ascii/AsciiSignature.php)

- Adding event Listeners

- Logging startup info

References

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Samples : https://github.com/bhagwat/spring-boot-samples

http://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsinglehttp://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#getting-started-gvm-cli-installationhttps://github.com/spring-projects/spring-boot/tree/master/spring-boot-cli/sampleshttp://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#using-boot-starter-pomshttp://spring.io/guides/gs/accessing-mongodb-data-rest/https://spring.io/guides/gs/accessing-data-mongodb/https://spring.io/guides/gs/accessing-data-jpa/

http://www.gradle.org/http://www.slideshare.net/Soddino/developing-an-application-with-spring-boot-34661781http://presos.dsyer.com/decks/spring-boot-intro.htmlhttp://pygments.org/ for nicely formatting code snippets included in presentation