Spring Boot Questions- Part 1

Posted 2020-11-19 VickyFengYu

• What is Spring Boot?

Spring Boot makes it easy to create stand-alone, production-grade Spring based Applications that you can “just run”.
You can use Spring Boot to create Java applications that can be started using java -jar or more traditional war deployments.

• What are the advantages of spring boot application?

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).
Opinionated view of the Spring platform and third-party libraries so you can get started with minimum fuss.
Absolutely no code generation and no requirement for XML configuration.
Provide a radically faster and widely accessible getting started experience for all Spring development.

• What are the requirements of Spring boot System?

Spring Boot 1.5.9.RELEASE requires
Java 7 +
Spring 4.3.13 +

For build support
Maven 3.2+
Gradle 2.9+

Container Support
Tomcat 7+
Jetty 8+ (Jetty 9.3 requires JDK 8 +)

Read more Spring boot system requirements

• What are the use of @EnableAutoConfiguration annotation?

This annotation tells Spring Boot to “guess” how you will want to configure Spring, based on the jar dependencies that you have added.

Read more @enableautoconfiguration spring boot example

• What is Spring Boot Starter?

Spring Boot provides a number of “Starters” that make easy to manage dependencies for your project.

Read More Spring boot starter

• What is spring-boot-starter-parent?

The spring-boot-starter-parent is a special starter that makes Maven or Gradle dependency-management easier by adding jars to your classpath.

Read More spring-boot-starter-parent

• What is spring-boot-starter-web?

This starter will add Tomcat and Spring MVC dependency to our application and its default configuration.

Read More spring-boot-starter-web

• How to create an executable jar using spring boot?

Add this below plugin to pom.xml

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Use mvn clean package to create executable jar file

Read More spring boot executable jar example

• How do you run and stop spring boot executable jar?

Open cmd or shell window and use java -jar as shown below

$ java -jar myproject-0.0.1-SNAPSHOT.jar

To stop use ctrl+C

Read More run spring boot jar from command line

• How do you change JDK version in spring boot?

Java 1.6 as the default compiler level.
You can overwrite it by adding java.version property tag as shown below

<properties>
    <java.version>1.8</java.version>
</properties>

• How to disable specific auto-configuration in spring boot?

You can use exclude property as shown below to disable specific auto configuration

@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})

• What is the use of @SpringBootApplication annotation?

The @SpringBootApplication annotation is equivalent to using @Configuration, @EnableAutoConfiguration and @ComponentScan with their default attributes

Since many spring Boot developers have their main class annotated with @Configuration, @EnableAutoConfiguration and @ComponentScan, spring boot provides you a new annotation @SpringBootApplication as replacement.