How to manage SpringBoot multiple modules in a unified manner

In Spring Boot, multi-module projects are a common architectural pattern, especially suitable for building large, complex applications. Splitting the application into multiple modules can improve code maintainability, reusability, and team collaboration efficiency. However, multi-module projects also bring some management challenges, such as dependency version management, build configuration management, dependency management between modules, etc. To solve these problems,Unified managementBecome crucial.

Below I will explain in detail how Spring Boot multi-module projects are managed uniformly and provide some best practices and tips.

1. Why do we need to uniformly manage multi-module Spring Boot projects?

In the absence of unified management, multi-module projects may encounter the following problems:

Dependency version conflict:

• Each module manages dependencies independently, and it is easy to introduce different versions of the same dependency library.
• Version incompatibility can lead to runtime conflicts, compilation errors, or unpredictable behavior.
• Troubleshooting and resolving dependency conflicts can become very time-consuming and complex.

Build configuration inconsistent:

• Different modules may use different Maven or Gradle plug-in versions and configurations.
• Inconsistent construction process may lead to inconsistent construction results of different modules, increasing integration risks.
• Maintaining and updating build configurations becomes dispersed and error-prone.

Repeat configuration:

• Each module needs to repeatedly configure some common information, such as Spring Boot version, public dependencies, plug-in configuration, etc.
• Code redundancy, reduces maintenance efficiency, and requires synchronization of multiple modules during modification.

Module dependency confusion:

• If the dependencies between modules are not clearly defined and managed, complex dependency loops or unnecessary dependencies are easily formed.
• Influences the compilation order and construction efficiency of modules, and increases the coupling between modules.

Difficulties in upgrading and maintenance:

• When you need to upgrade Spring Boot version or public dependency library, you need to modify and test module by module, which is very laborious and easy to miss.
• The maintenance cost is high and the upgrade risk is high.

2. The core idea of ​​unified management

The core idea of ​​unified management of Spring Boot multi-module projects is:Centralized configuration, agreements are better than configuration, reduce repetitive work, and improve consistency and maintainability.

It is mainly achieved through the following aspects:

Use parent module (Parent POM/Build Script):

• Create a parent module as the root module for the entire project.
• Parent module's(Maven) or(Gradle) files are used to centrally manage common configurations and dependencies.
• Other modules are submodules and inherit the configuration of the parent module.

Dependency Management:

• In parent moduledependencyManagementPartially declares version information for all public dependencies.
• Submodules only need to declare dependenciesgroupIdandartifactId, version information is inherited from the parent module.
• Ensure that the entire project uses a unified dependent version to avoid version conflicts.

Plugin Management:

• In parent modulepluginManagementPartially declare the version and configuration information of the public plug-in.
• Submodules only need to declare the plug-ins that need to be used, and the version and common configuration inherit from the parent module.
• Ensure that the entire project uses consistent plug-in versions and configurations, and improve the consistency of the build process.

Property Management:

• In parent modulepropertiesSome public attributes are defined in part, such as Spring Boot version, Java version, public dependency version, etc.
• Submodules can directly reference attributes defined by the parent module, which facilitates unified modification and management.

Build Profile Management:

• Define a build profile in the parent module, e.g.dev、test、prodetc., used to manage build configurations in different environments.
• Submodules can inherit the parent module's Profile configuration, or customize the Profile as needed.

Module Dependency Management:

• In the moduleorDependencies between modules are explicitly declared.
• Maven or Gradle automatically manages the compilation and build order of modules based on dependencies.

III. Unified management practices between Maven and Gradle

Whether using Maven or Gradle build tools, unified management of Spring Boot multi-module projects can be achieved. The following are the practice methods of Maven and Gradle:

1. Maven multi-module unified management

Parent moduleExample (simplified version):

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="/POM/4.0.0"
         xmlns:xsi="http:///2001/XMLSchema-instance"
         xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.">
    <modelVersion>4.0.0</modelVersion>

    <groupId></groupId>
    <artifactId>parent-module</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>pom</packaging>  <!-- Parent modulepackagingMust bepom -->

    <modules>
        <module>module-a</module>
        <module>module-b</module>
        <module>module-c</module>
        </modules>

    <properties>
        <>1.8</>
        <>2.7.0</>
        <>3.12.0</>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId></groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId></groupId>
                <artifactId>commons-lang3</artifactId>
                <version>${}</version>
            </dependency>
            <!-- Other public dependencies -->
        </dependencies>
    </dependencyManagement>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId></groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <version>${}</version>
                </plugin>
                <!-- Other public plug-in configurations -->
            </plugins>
        </pluginManagement>
    </build>

</project>

SubmodulesExample (e.g.module-a):

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="/POM/4.0.0"
         xmlns:xsi="http:///2001/XMLSchema-instance"
         xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId></groupId>
        <artifactId>parent-module</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../</relativePath>  <!-- Point to parent module -->
    </parent>

    <artifactId>module-a</artifactId>
    <version>1.0.0-SNAPSHOT</version>  <!-- Version number can be omitted，Default inheritance of parent module -->
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId></groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId></groupId>
            <artifactId>commons-lang3</artifactId>  <!-- Version number inherits from parent module -->
        </dependency>
        <dependency>
            <groupId></groupId>
            <artifactId>module-b</artifactId> <!-- Inter-module dependencies -->
            <version>1.0.0-SNAPSHOT</version> <!-- Version number inherits from parent module，But explicit declarations are clearer -->
        </dependency>
    </dependencies>

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

</project>

Key points of Maven unified management:

• Parent modulepackaging forpom: Declare the parent module to be of POM type and is used to manage other modules.
• <modules>Label: List all child modules in the parent module.
• <parent>Label: SubmoduleUsed in<parent>The tag points to the parent module to establish an inheritance relationship.
• <dependencyManagement>: Used in the parent moduledependencyManagementCentrally manage dependent versions.
• <pluginManagement>: Used in the parent modulepluginManagementCentrally manage plug-in versions and configurations.
• propertyproperties: Public properties are defined in the parent module, and submodules can be referenced directly.
• relativePath: <parent>In the tagrelativePathPoint to parent modulerelative path.
• Inter-module dependencies: use<dependency>Tags declare dependencies between modules,groupIdandversionStay consistent.

2. Gradle multi-module unified management

(Root directory):Declare the modules included in the project

 = "parent-module"
include("module-a")
include("module-b")
include("module-c")

Root directory(Parent module build script):

plugins {
    java
    // Use Spring Boot plugin, but not applied to the parent module (apply false)    id("") version "2.7.0" apply false
    id("-management") version "1.0." apply false
}

allprojects {
    group = ""
    version = "1.0.0-SNAPSHOT"
}

subprojects {
    apply(plugin = "java")
    apply(plugin = "-management")

    repositories {
        mavenCentral()
    }

    dependencies {
        implementation(":commons-lang3:3.12.0")
        // Other public dependencies    }

    dependencyManagement {
        imports {
            mavenBom(.BOM_COORDINATES)
        }
    }
}

Submodulesmodule-a/Example:

plugins {
    id("")
    id("-management")
}

dependencies {
    implementation(":spring-boot-starter-web")
    implementation(project(":module-b")) // Inter-module dependencies}

Key points of Gradle unified management:

• : useinclude()Function declaration submodules.
• Root directory: As the build script of the parent module, usesubprojects {}Configure the common configuration of all submodules.
• dependencyManagement: Used in the parent moduledependencyManagementImport the BOM (Bill of Materials) of Spring Boot and manage public dependency versions.
• allprojects {}: Configure properties common to all modules (e.g.group, version)。
• Inter-module dependencies: useimplementation(project(":module-b"))Declare dependencies between modules.

4. Best practices and techniques

1. Clarify module division: Rationally divide the boundaries of the module to ensure that the module responsibilities are single, high cohesion and low coupling.
2. The parent module has clear responsibilities: The parent module is only responsible for unified management of configuration and dependencies, and does not include business code.
3. Dependency version: Always in the parent moduledependencyManagementManage dependent versions in the submodule to avoid explicitly specifying the version in the submodule.
4. Public dependencies and centralized management of plug-ins: Place all public dependencies and plug-in configurations in the parent module to reduce duplicate configurations of submodules.
5. Use attribute management: Using parent modulepropertiesDefine public attributes, such as Spring Boot version, public dependency version, etc., for convenient unified modification.
6. Clear module dependencies: Clearly declare dependencies between modules to avoid circular dependencies and unnecessary dependencies.
7. Use dependencies Scope: Choose the appropriate Scope according to the purpose of the dependency (e.g.compile, runtime, testwait).
8. Build Profile using: Use the build profile reasonably to manage build configurations in different environments.
9. Continuous integration and automation construction: Combined with CI/CD tools, realize the automated construction, testing and deployment of multi-module projects.
10. IDE Support: Multi-module project support features such as IntelliJ IDEA or Eclipse for easy management and development of multi-module projects.

5. Summary

The unified management of Spring Boot multi-module projects is the key to building large, maintainable applications.

By using parent modules, dependency management, plug-in management, attribute management and other technologies, the management challenges brought by multi-module projects can be effectively solved, development efficiency, maintenance costs, and ultimately built a more robust and scalable Spring Boot application.

The above is personal experience. I hope you can give you a reference and I hope you can support me more.