How does Maven version management work? How to manage dependency versions?

Maven version management follows the Semantic Versioning specification, using a three-part version number format: MAJOR.MINOR.PATCH. Understanding Maven version management is crucial for dependency management and project release.

Version Number Format:

• MAJOR: Incompatible API changes
• MINOR: Backwards-compatible functionality additions
• PATCH: Backwards-compatible bug fixes

Version Number Examples:

• 1.0.0: First stable version
• 1.2.3: Major version 1, minor version 2, patch version 3
• 2.0.0: Incompatible major version upgrade

Version Range Specifiers:

1. Exact Version: 1.0.0, use only the specified version
2. Range Versions:
   • [1.0,2.0): Greater than or equal to 1.0 and less than 2.0
   • (1.0,2.0]: Greater than 1.0 and less than or equal to 2.0
   • [1.0,]: Greater than or equal to 1.0
   • [,1.0]: Less than or equal to 1.0
3. Wildcard Versions:
   • 1.0.* or 1.0: Any version of 1.0.x
   • 1.* or 1: Any version of 1.x
4. Latest Versions:
   • LATEST: Latest released version
   • RELEASE: Latest stable version
5. Snapshot Versions: 1.0-SNAPSHOT, version in development

SNAPSHOT Versions:

• SNAPSHOT is a Maven-specific version identifier, indicating a version in development
• Each time Maven builds, it checks the remote repository for updated SNAPSHOT versions
• SNAPSHOT versions should not be used in production environments
• When releasing, SNAPSHOT should be replaced with a formal version number

Version Management Best Practices:

1. Use dependencyManagement to uniformly manage versions:

xml
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.3.20</version>
        </dependency>
    </dependencies>
</dependencyManagement>

1. Use BOM (Bill of Materials) to manage versions:

xml
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>2.7.0</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

1. Use properties to define version numbers:

xml
<properties>
    <spring.version>5.3.20</spring.version>
    <mybatis.version>3.5.9</mybatis.version>
</properties>

Version Conflict Resolution:

1. Shortest Path First: Choose the version with the shortest dependency path
2. Declaration Order First: Choose the version declared first in pom.xml
3. Force Specified Version: Directly declare the required version to override transitive dependencies

Version Release Process:

1. Use SNAPSHOT version during development
2. After testing passes, remove SNAPSHOT identifier
3. Use mvn release:prepare to prepare release
4. Use mvn release:perform to execute release
5. Publish to repository for use by other projects

Version Check Commands:

• mvn versions:display-dependency-updates: View updatable dependencies
• mvn versions:display-plugin-updates: View updatable plugins
• mvn versions:display-property-updates: View updatable properties
• mvn versions:use-latest-releases: Update to latest stable versions

Notes:

• Avoid using LATEST and RELEASE, which may cause build instability
• Do not use SNAPSHOT versions in production environments
• Regularly update dependency versions to fix security vulnerabilities
• Be cautious when using version ranges to avoid introducing incompatible updates
• Lock dependency versions in CI/CD processes to ensure reproducible builds

Reasonable version management can improve project stability and maintainability.