Custom Spring Boot starters are valuable for encapsulating common functionalities, such as integrating with notification services like Feishu or DingTalk, or standardizing response code handling.

Project Setup

1. Initialize a Maven Project: Create a new Maven project, for instance, named holmium-spring-boot-starter.

2. Implement Core Functionality and Configuration:

   • Functionality Class: Define the core class that provides the desired functionality. For example, a User class:

     package com.holmium.framwork.core;
     
     public class User {
         private String name;
         private int age;
     
         public User() {
             this.name = "xjh";
             this.age = 18;
         }
     
         @Override
         public String toString() {
             return "User{" +
                     "name='" + name + '\'' +
                     ", age=" + age +
                     '}';
         }
     }
     

   • Auto-Configuration Class: Create a configuration class to automatically register beans when the starter is included. Use @ConditionalOnClass to ensure the bean is created only if the specified class is present.

     package com.holmium.framwork.core;
     
     import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
     import org.springframework.context.annotation.Bean;
     import org.springframework.context.annotation.Configuration;
     
     @Configuration
     public class UserAutoConfiguration {
     
         @Bean
         @ConditionalOnClass(User.class)
         public User myUser() {
             return new User();
         }
     }
     

3. Define spring.factories: In the src/main/resources directory, create a META-INF folder and in side it, a spring.factories file. This file tells Spring Boot which auto-configuration classes to load.

   org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
     com.holmium.framwork.core.UserAutoConfiguration
   

4. Include Spring Boot Starter Dependency: Ensure your starter project includes the core Spring Boot starter dependency in its pom.xml:

   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter</artifactId>
       <version>2.6.13</version>
   </dependency>
   

5. Incorporate the Starter into Another Project:

   Add the custom starter as a dependency in the pom.xml of the project where you intend to use it. You can usually do this through your IDE by searching for the artifact.

   <dependency>
       <groupId>com.holmium</groupId>
       <artifactId>holmium-spring-boot-starter</artifactId>
       <version>1.0-SNAPSHOT</version>
   </dependency>
   

6. Test the Integration:

   Create a test case in your consuming project to verify that the beans provided by the starter are available and functioning correctly.

   package com.example.demo;
   
   import com.holmium.framwork.core.User;
   import org.junit.jupiter.api.Test;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.boot.test.context.SpringBootTest;
   
   @SpringBootTest
   class CustomStarterIntegrationTest {
   
       @Autowired
       private User injectedUser;
   
       @Test
       void testStarterComponent() {
           System.out.println(injectedUser);
           // Add assertions here to verify user properties or behavior
       }
   }