创建启动器项目
添加启动器相关依赖
创建属性配置类
创建自动配置
编写自动配置文件spring.factories
使用自定义的启动器

这里我拿定义一个连接池启动器举例

实现: 当用户引入了连接池启动依赖,并配置相应配置文件,项目自动配置连接池

1,创建启动器项目

创建项目 spring-boot-jdbc-starter 引入依赖

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.3.6.RELEASE</version>
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <!--引入spring‐boot‐starter；所有starter的基本配置-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>

    <!--自动配置连接池-->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.1.12</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-configuration-processor</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>

2,创建属性配置类

import org.springframework.boot.context.properties.ConfigurationProperties;

@Component
@ConfigurationProperties(prefix = "spring.jdbc.datasource")
public class DataSourceProperties {
    private String driverClassName ;
    private String url;
    private String username;
    private String password;
    // 生成set get 方法   
}

3,创建自动配置

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import javax.sql.DataSource;

@SpringBootConfiguration
@EnableConfigurationProperties(DataSourceProperties.class)
public class DataSourceAutoConfiguration {

    @Autowired
    private DataSourceProperties dataSourceProperties ;

    @Bean
    public DataSource createDataSource(){
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(dataSourceProperties.getDriverClassName());
        dataSource.setUrl(dataSourceProperties.getUrl());
        dataSource.setUsername(dataSourceProperties.getUsername());
        dataSource.setPassword(dataSourceProperties.getPassword());
        return dataSource;
    }
}

4,编写自动配置文件spring.factories

在 resources 文件夹下面新建 META-INF/spring.factories

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.wiselzx.autoconfig.DataSourceAutoConfiguration

做完了之后注意要执行install , 安装项目到本地maven仓库

5,使用自定义的启动器

在新项目中引入依赖

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

配置连接池信息 新建 application-datasource.yml

spring:
  jdbc:
    datasource:
      driverClassName: com.mysql.jdbc.Driver
      url: jdbc:mysql:///database
      username: root
      password: 123456

激活配置文件 application.yml

spring:
  profiles:
    active: datasource

关于为何在 resources 文件夹下面新建 META-INF/spring.factories 我会在"Spring Boot自动配置原理" juejin.cn/post/723555…中说明

如何自定义一个spring-boot-starter