自己写一个spring boot starter

(1) 新建项目
项目名:formatter-spring-boot-starter

(2) 定义pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>first-app-by-gui</artifactId>
        <groupId>thinking-in-spring-boot</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>formatter-spring-boot-starter</artifactId>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <version>2.3.4.RELEASE</version>
<!--            细节，防止依赖传递，避免其他项目引用该项目之后版本冲突-->
            <optional>true</optional>
        </dependency>

    </dependencies>
</project>

(3) 写一个接口和实现

public interface Formatter {

    String format(Object object);
}

public class DefaultFormatter implements Formatter{

    @Override
    public String format(Object object) {
        return String.valueOf(object);
    }
}

(4) 配置类

@Configuration
public class FormatterAutoConfiguration {

    @Bean
    public Formatter defaultFormatter(){
        return new DefaultFormatter();
    }
}

(5) 配置文件
写一个META-INF/spring.factories文件,内容如下:

org.springframework.boot.autoconfigure.EnableAutoConfiguration=thinking.in.spring.boot.config.FormatterAutoConfiguration

完成之后如果需要使用就引入这个项目,就可以直接使用里面的接口了.