spring-014: mvn spring-boot:run-lifecycle-phases

When you start your Spring Boot app using mvn spring-boot:run, Maven executes the necessary lifecycle phases in order. Here’s what happens at each phase:

1️⃣ validate Phase

What happens?

• Maven checks the project structure and pom.xml configuration.
• Ensures all required properties are defined.
• Verifies that all dependencies are resolved (if any are missing, Maven will try to download them).

Key tasks:

• Ensures all necessary files exist (e.g., src/main/java, pom.xml).
• Validates if groupId, artifactId, and version are correctly defined.

If an issue is found (e.g., missing dependencies), Maven stops here with an error.

2️⃣ compile Phase

What happens?

• Compiles Java source code (.java → .class files).
• Stores compiled .class files inside target/classes/.

Key tasks:

• Uses the Maven Compiler Plugin to compile source files.
• If annotation processing (e.g., Lombok) is enabled, it processes those annotations.

If compilation fails due to syntax errors, Maven stops here.

3️⃣ package Phase

What happens?

• Creates a JAR/WAR file containing the compiled classes and resources.
• Moves the packaged file to target/your-app.jar (for Spring Boot, a fat JAR is created).

Key tasks:

• Runs spring-boot-maven-plugin (for Spring Boot apps) to package dependencies into the JAR.
• Includes META-INF/MANIFEST.MF (defines the main class to run).
• Copies src/main/resources/ files into the JAR.

If packaging fails (e.g., missing files), Maven stops here.

4️⃣ spring-boot:run (Runs the App)

• JVM starts and loads Demo1Application.main().
• Spring Boot initializes the app, loads dependencies, and starts an embedded web server (if applicable).
• The app is now running and ready to serve requests.

Summary of Lifecycle Execution Before spring-boot:run

These phases ensure that when your app starts, everything is correctly compiled and packaged, preventing runtime errors.

原文链接：spring-014: mvn spring-boot:run-lifecycle-phases