Spring boot introduction

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Spring Boot Introduction
Presenter: Rasheed Amir

Who is Rasheed?
❏ Programmer (Java, Groovy, C#, JavaScript). Architect. Agile Coach.
❏ Co-founder Aurora Solutions, FixTelligent
❏ Serial Entrepreneur
❏ Certified Instructor for Spring Courses (Core, Web & Integration)
❏ You can find me on LinkedIn

Overview

Spring Boot Goals
➔ Introduce developers to Spring Boot, an opinionated way to rapidly build production
grade Spring applications quickly and with minimal fuss.
➔ Be opinionated out of the box, but get out of the way quickly as requirements start to
diverge from the defaults
➔ 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)
➔ Absolutely no code generation and no requirement for XML configuration!

Spring Boot Goals...
➔ Single point of focus (as opposed to large collection of spring-* projects)
➔ A tool for getting started very quickly with Spring
➔ Common non-functional requirements for a "real" application
➔ Exposes a lot of useful features by default
➔ Gets out of the way quickly if you want to change defaults

Installation
Spring Boot CLI

Installation - Spring CLI
Spring CLI Installer -- Installer for the spring CLI command on Un*x-like system (should work
on Linux, Mac or Cygwin).
You can curl http://start.spring.io/install.sh | sh, or download the script and run it.

Getting Started Quickly!
in Groovy!

Getting Started Quickly in Groovy!
Here’s a really simple web application that you can use to test your installation. Create a file
called Welcome.groovy:
@RestController
class WelcomeToSpringBootMeetup {
@RequestMapping("/")
String home() {
"Welcome Everyone!"
}
}
$ spring run --watch Welcome.groovy
... application is running at http://localhost:8080

How did it work?
// import org.springframework.web.bind.annotation.RestController
// other imports …
@RestController
String home() {
"Welcome Everyone!"
}
}

How did it work?
// @Grab("org.springframework.boot:spring-boot-web-starter:0.5.0")
@RestController
String home() {
"Welcome Everyone!"
}
}

How did it work?
// @EnableAutoConfiguration
@RestController
String home() {
"Welcome Everyone!"
}
}

How did it work?
// @EnableAutoConfiguration
@RestController
String home() {
"Welcome Everyone!"
}
// public static void main(String[] args) {
// SpringApplication.run(Example.class, args);
// }
}

Getting Started Quickly!
in Java!

Getting Started Quickly in Java!
Step 1: Create a folder; name it “helloworld”. Create an empty file called “pom.xml”. Copy the
content given below...
Step 2: Run mvn package
Step 3: Run mvn dependency:tree
Step 4: Add spring-boot-starter-web dependency in pom
Step 5: Run mvn dependency:tree
Step 6: Create directory structure (src/main/java/com/helloworld) and file named “HelloWorld.
java”. Copy the code give below...
Step 7: Running the HelloWorld: mvn spring-boot:run
Step 8: Open the browser: If you open a web browser to http://localhost:8080 and you will see
something…
Step 9: Create executable jar....

Starter POM’s
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
➔ Standard Maven POMs
➔ Define dependencies that we recommend
➔ Parent optional
➔ Available for web, batch, integration, data, amqp, aop, jdbc, ...
➔ e.g. data = hibernate + spring-data + JSR 303

SpringApplication
SpringApplication app = new SpringApplication(MyApplication.class);
app.setShowBanner(false);
app.run(args);
➔ Gets a running Spring ApplicationContext
➔ Uses EmbeddedWebApplicationContext for web apps
➔ Can be a single line: SpringApplication.run(MyApplication.class, args)

SpringApplication
@Configuration
@EnableAutoConfiguration
public class Welcome {
}
➔ Attempts to auto-configure your application
➔ Backs off as you define your own beans
➔ Regular @Configuration classes
➔ Usually with @ConditionalOnClass and @ConditionalOnMissingBean

Production Packaging
Maven plugin (using spring-boot-starter-parent):
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
$ mvn package or mvn clean install
$ java -jar <file-name>.jar

Production Packaging
$ java -jar <file-name.jar>
➔ Easy to understand structure
➔ No unpacking or start scripts required
➔ Typical REST app ~10Mb

Command Line Arguments
@Value("${name}")
private String name;
SpringApplication adds command line arguments to the Spring Environment so you can refer
inject them into beans:
$ java -jar <file-name>.jar --name=Rasheed
You can also configure many aspects of Spring Boot itself:
$ java -jar <file-name>.jar --server.port=9999

Externalizing Configuration to Properties
server.port: 9000
Just put application.properties in your classpath or next to you jar, e.g.
application.properties
Properties can be overridden (command line arg > file > classpath)

Using YAML
server:
port: 9000
Just include snake-yaml.jar and put application.yml in your classpath e.g.
application.yml
Both properties and YAML add entries with period-separated paths to the Spring Environment.

Binding Configuration To Beans
@ConfigurationProperties(prefix="mine")
public class MyPoperties {
private Resource location;
private boolean skip = true;
// ... getters and setters
}
MyProperties.java
application.properties
mine.location: classpath:mine.xml
mine.skip: false
Explore ServerProperties.java

Customizing Configuration Location
Set
➔ spring.config.name - default application, can be comma-separated list
➔ spring.config.location - a Resource path, overrides name
$ java -jar <file-name>.jar --spring.config.name=production

Spring Profiles
Activate external configuration with a Spring profile file name convention e.g. application-development.
properties
or nested documents in YAML:
defaults: etc…
---
spring:
profiles: development, qa
other:
stuff: more stuff...
application.yml
Set the default spring profile in external configuration, e.g: application.properties
spring.profiles.active: default, qa

Logging
➔ Spring Boot provides default configuration files for 3 common logging frameworks:
logback, log4j and java.util.logging
➔ Starters (and Samples) use logback with colour output
➔ External configuration and classpath influence runtime behavior
➔ LoggingApplicationContextInitializer sets it all up

Autoconfigured Behavior
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
</dependency>
Let’s extend the demo and see what we can get by just modifying the classpath, e.g.
● Add an in memory database

Available Autoconfigured Behaviour...
● Embedded servlet container (Tomcat or Jetty)
● JDBC: DataSource and JdbcTemplate
● JPA, JMS, AMQP (Rabbit), AOP
● Websocket
● Spring Data JPA (scan for repositories) and Mongodb
● Thymeleaf
● Mobile
● Batch processing
● Reactor for events and async processing
● Actuator features (Security, Audit, Metrics, Trace)

The Actuator
Monitoring Endpoints

The Actuator
Adds common non-functional features to your application and exposes MVC endpoints to
interact with them.
Provides following endpoints: /metrics, /health, /trace, /dump, /shutdown, /beans, /env, /info

Spring Boot Modules

● Spring Boot - main library supporting the other parts of Spring Boot
● Spring Boot Autoconfigure - single @EnableAutoConfiguration annotation creates a
whole Spring context
● Spring Boot Starters - a set of convenient dependency descriptors that you can include in
your application.
● Spring Boot CLI - compiles and runs Groovy source as a Spring application
● Spring Boot Actuator - common non-functional features that make an app instantly
deployable and supportable in production
● Spring Boot Tools - for building and executing self-contained JAR and WAR archives
● Spring Boot Samples - a wide range of sample apps

Build WAR file!

Spring boot introduction

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