Spring Boot

Links#

https://docs.spring.io/spring-boot/maven-plugin/
https://docs.spring.io/spring-boot/appendix/dependency-versions/index.html
https://docs.spring.io/spring-boot/reference/using/build-systems.html

1. Important Points#

starter:
    Spring Boot 提供的一组 dependency shortcut，例如 web、data-jpa、test

spring-boot-starter-parent:
    parent POM, provides dependency versions and plugin defaults

spring-boot-dependencies:
    BOM, only provides dependency versions

2. Use Starter Parent#

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>3.3.1</version>
  <relativePath/>
</parent>

<groupId>com.example</groupId>
<artifactId>order-api</artifactId>
<version>1.0.0-SNAPSHOT</version>

<properties>
  <java.version>21</java.version>
</properties>

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
  </dependency>
</dependencies>

use when:
    application can inherit Spring Boot parent directly

3. Use BOM Without Parent#

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-dependencies</artifactId>
      <version>3.3.1</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

use when:
    company parent POM must be inherited
    Spring Boot only provides dependency versions

4. Starters#

Starter	Use
`spring-boot-starter-web`	Spring MVC / embedded Tomcat
`spring-boot-starter-webflux`	reactive HTTP
`spring-boot-starter-data-jpa`	JPA / Hibernate
`spring-boot-starter-validation`	Bean Validation
`spring-boot-starter-actuator`	health, metrics, management endpoints
`spring-boot-starter-test`	test stack

5. Spring Boot Maven Plugin#

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

./mvnw spring-boot:run
./mvnw clean package
java -jar target/order-api-1.0.0-SNAPSHOT.jar

repackage:
    turns normal jar into executable Spring Boot jar

6. Profiles#

./mvnw -Pprod clean package
java -jar app.jar --spring.profiles.active=prod

Maven profile:
    changes build behavior

Spring profile:
    changes application runtime configuration

7. Override Boot Managed Version#

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.17.2</version>
    </dependency>
  </dependencies>
</dependencyManagement>

use only when:
    security fix or compatibility requirement is clear
    tests verify Spring Boot compatibility

8. Multi Module Pattern#

root pom:
    packaging=pom
    imports spring-boot-dependencies
    owns pluginManagement

application module:
    depends on internal library modules
    enables spring-boot-maven-plugin

library module:
    normal jar
    usually should not enable repackage