Spring Boot
- 1. Spring Boot
- 2. © copyright : spiraltrain@gmail.com Course Schedule 2 • What is Spring Boot? • Advantages Spring Boot • Goal of Spring Boot • Spring Boot Flavors • Key Spring Boot Components • Spring Boot Starter • Starter Dependencies • Spring Boot Autoconfigurator • @SpringBootApplication • Spring Boot CLI • Spring Boot Internals • Spring Boot Actuator • Reflection • Annotations • Spring Core • Aspect Orientation • Groovy • Spring Boot
- 3. www.spiraltrain.nl What is Spring Boot? • Spring Boot is completely new project from Spring Team : • Framework developed on top of existing Spring Framework • Spring Boot uses new model to make Java Development easy : • Avoids some tedious development steps and boilerplate code and configuration • Provides defaults for code and annotation configuration • Follows Opinionated Defaults Configuration Approach • Spring Boot Framework is not implemented from scratch : • Rather it is implemented on top of existing Spring Framework • Used to solve same problems like Spring Framework 3 Spring Boot Spring Framework Embedded HTTP Servers (Tomcat, Jetty) XML<bean> Configuration or @Configuration = + - Spring Boot
- 4. www.spiraltrain.nl Advantages Spring Boot • Easy to develop Spring Based applications with Java or Groovy : • Reduces development time and increases productivity • Avoids writing lots of boilerplate Code : • Annotations and XML Configuration. • Easy to integrate Spring Boot Applications with Spring Ecosystem : • Like Spring JDBC, Spring ORM, Spring Data, Spring Security etc. • Provides Embedded HTTP servers like Tomcat, Jetty etc. : • Allows develop and test web applications very easily • Provides CLI Command Line Interface tool : • Allows develop and test Spring Boot Applications from command prompt easily • Provides lots of plugins : • Allows develop and test Spring Boot Applications easily using Maven and Gradle • Allows working with embedded and in-memory Databases easily 4Spring Boot
- 5. www.spiraltrain.nl Goal of Spring Boot • Main goal of Spring Boot is to reduce Development time : • Unit Test and Integration Test time • Ease the development of Production ready web applications • Spring Boot features that accomplish this : • Avoid XML Configuration completely • Avoid defining more Annotation Configuration : • Combines existing Spring Framework Annotations to simple and single Annotation • Avoid writing lots of import statements • Provide some defaults to quick start new projects within no time • Provide Opinionated Development approach • Limitations of Spring Boot : • Time consuming to convert Spring Framework projects into Spring Boot Applications • However it is easy to create brand new/Greenfield Projects using Spring Boot • Three approaches to start opiniated development : • Spring Boot CLI Tool, Spring STS IDE, Spring Initializr Website 5Spring Boot
- 6. www.spiraltrain.nl Spring Boot Flavors • Two flavors of Spring-Based Applications using Spring Boot : • Java-Based Applications and Groovy Applications • Spring Boot Groovy Applications : • Spring Boot CLI or Spring STS IDE or Spring Initializr Website • Spring Initializr Website is found at: http://start.spring.io/ • Spring Boot Java Applications : • Spring STS IDE or Spring Initializr Website • Groovy is also JVM language almost similar to Java Language : • Can combine both Groovy and Java into one Project • Groovy files are finally compiled into *.class files with same byte code format 6 Java *.java Compiler javac of groovyc *.class files Byte Code Groovy *.groovy Spring Boot
- 7. www.spiraltrain.nl Key Spring Boot Components • Spring Boot Framework has mainly four major Components : • Spring Boot Starters • Spring Boot AutoConfigurator • Spring Boot CLI • Spring Boot Actuator • In addition there are two more Spring Boot components : • Spring Initilizr and Spring Boot IDEs • Use Spring Initializr web interface at http://start.spring.io : • To quick start new Spring Boot projects 7 CLI Actuator Autoconfigurator Starter Spring Boot Components Spring Boot
- 8. www.spiraltrain.nl Spring Boot Starter • Combines group of related dependencies in single dependency • Example for Spring WebApplication with Tomcat WebServer : • Need minimal jar dependencies in your Maven’s pom.xml : • Spring core Jar file spring-core-xx.jar, Spring Web Jar file spring-web-xx.jar • Spring Web MVC Jar file spring-webmvc-xx.jar ,Servlet Jar file servlet-xx.jar • Need to add database related jars to add some database stuff : • Spring JDBC Jar file spring-jdbc-xx.jar, Spring ORM Jar files spring-orm-xx.jar • Spring Transaction Jar file spring-transaction-xx.jar • Need to define lot of dependencies in build files : • Very tedious and cumbersome tasks and also it increases our build file size • Solution is to use Spring Boot Starter component : • Spring Boot Starter component combines all related jars into single jar file • We need to add one and only one jar file spring-boot-starter-web.jar file • When adding spring-boot-starter-web.jar file dependency : • Spring Boot downloads all required jars and adds them to project classpath 8Spring Boot
- 9. www.spiraltrain.nl Starter Dependencies • spring-boot-starter-logging jar file : • Loads all it’s dependency jars to project classpath like : • jcl-over-slf4j, jul-to-slf4j,log4j-over-slf4j, logback-classic 9 spring-boot-starter-web spring-boot-starter spring-web spring-webmvc spring-boot-starter-tomcat spring-boot spring-boot-autoconfigure spring-boot-starter-logging Tomcat-embed-core Tomcat-embed-logging- juli Spring Boot
- 10. www.spiraltrain.nl Spring Boot AutoConfigurator • Most of the Spring IO Platform Critics : • Spring-based application requires lot of configuration either with XML or annotations • Solution to this problem is Spring Boot AutoConfigurator : • Don’t need to define XML configuration and almost no Annotation configuration • Spring Boot AutoConfigurator component will take care of providing this information • Spring MVC application using Spring IO Platform : • Define lot of XML Configuration like views, view resolvers etc • If using spring-boot-starter-web jar file in project build file : • Spring Boot AutoConfigurator will resolve views, view resolvers etc. automatically • Also Spring Boot reduces Annotation configuration : • If we use @SpringBootApplication annotation at class level • Spring Boot AutoConfigurator automatically adds required annotations to Java ByteCode • Spring Boot Starter reduces build’s dependencies : • Spring Boot AutoConfigurator reduces the Spring Configuration • Spring Boot Starter triggers Spring Boot AutoConfigurator automatically 10Spring Boot
- 11. www.spiraltrain.nl @SpringBootApplication • Definition for @SpringBootApplication : @Target(value=TYPE) @Retention(value=RUNTIME) @Documented @Inherited @Configuration @EnableAutoConfiguration @ComponentScan public @interface SpringBootApplication 11 SpringBootApplication @Configuration @ComponentScan @EnableAutoConfiguration= + + Spring Boot
- 12. www.spiraltrain.nl Spring Boot CLI • Spring Boot Command Line Interface : • Spring Boot software to run and test Spring Boot applications from command line • When running Spring Boot Applications through CLI : • Internally uses Spring Boot Starter and Spring Boot AutoConfigurate components • Spring Boot CLI introduced spring command : • Execute Groovy Scripts from command prompt spring run HelloWorld.groovy • Can run Spring Web Applications with simple Spring Boot CLI Commands • Spring Boot Framework internally uses Groovy : • Add some defaults like Default import statements, Application main() method etc. • Groovy language contains JAR Dependency Resolver : • Resolves and add all required jar files to Groovy Project classpath • Groovy Compiler groovyc : • Will automatically add all default import statements then compile it 12Spring Boot
- 13. www.spiraltrain.nl Spring Boot Internals • Spring Boot Framework Programming model : • Mainly inspired by Groovy Programming model • Spring Boot Framework depends on two major components : • Groovy and Grape • Grape is an Embedded Dependency Resolution engine : • JAR Dependency Manager embedded into Groovy • Adds maven dependencies to project classpath to reduce build file definitions 13 Spring Boot Groovy Groovy’s Grape Spring Boot
- 14. www.spiraltrain.nl Spring Boot Actuator • Spring Boot Actuator components major features are : • Providing Management EndPoints to Spring Boot Applications. • Spring Boot Applications Metrics • For Spring Boot Web Application using CLI : • Spring Boot Actuator provides hostname localhost and default port number 8080 • Application is accessed with http://localhost:8080/ end point • Most common endpoints Boot provides out of the box : • /health – Shows application health information • /info – Displays arbitrary application info • /metrics – Shows ‘metrics’ information for the current application • /trace – Displays trace information by default the last few HTTP requests • In order to get it working : • Actuator requires Spring MVC to expose its endpoints through HTTP • No other technology is supported 14Spring Boot
- 15. © copyright : spiraltrain@gmail.com Summary : Spring Boot • Spring Boot uses new model to make Java Development easy : • Avoids some tedious development steps and boilerplate code and configuration • Provides defaults for code and annotation configuration • Follows Opinionated Defaults Configuration Approach • Three approaches to start opiniated development : • Spring Boot CLI Tool, Spring STS IDE, Spring Initializr Website • Two flavors of Spring-Based Applications using Spring Boot : • Java-Based Applications and Groovy Applications • Spring Boot Framework has mainly four major Components : • Spring Boot Starters, Spring Boot AutoConfigurator, Spring Boot CLI, Spring Boot Actuator • Spring Boot Starters : • Combines group of related dependencies in single dependency • Spring Boot Framework depends on two major components : • Groovy and Grape Spring Intro 15 Exercises Spring Boot