前段时间，SpringBoot 出 3.x 版本了。听说把自动配置给刀了！！（3.x版本不再使用 spring.factories做自动配置）
但是这个在真正开始说要弃用，是在 2.7版本。只是向下兼容了 spring.factories 的配置方式。
也就是说两种写法共存，如下图：
在 META-INF 目录下增加了 spring 目录，其中有文件 org.springframework.boot.autoconfigure.AutoConfiguration.imports
文件内容是配置类的完整类名。
比如我当前使用的配置内容是：
org.feng.config.AppInfoConfiguration
而 spring.factories 中的配置内容和之前一致：
org.springframework.boot.autoconfigure.EnableAutoConfiguration=org.feng.config.AppInfoConfiguration
这一点其实也可以从 Spring 的源码包中看到：
https://gitee.com/fengsoshuai/custom-springboot-starter-demo.git
| 模块 | 说明 |
|---|---|
| customer-starter | 自定义的 starter，并提供配置、示例接口&实现类 |
| test | 测试自定义starter，引入自定义starter的依赖，并定义了启动类，控制器类 |
主要定义了 SpringBoot的版本。
<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">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>custom-springboot-starter-demo</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<name>custom-springboot-starter-demo</name>
<url>http://maven.apache.org</url>
<modules>
<module>custom-starter</module>
<module>test</module>
</modules>
<properties>
<java.version>11</java.version>
<maven.compiler.source>11</maven.compiler.source>
<maven.compiler.target>11</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<springboot.dependencies.version>2.7.8</springboot.dependencies.version>
</properties>
<dependencyManagement>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-dependencies -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>${springboot.dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>11</source>
<target>11</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
</project><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">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.example</groupId>
<artifactId>custom-springboot-starter-demo</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<artifactId>custom-starter</artifactId>
<packaging>jar</packaging>
<name>custom-starter</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
<build>
<!-- 将自定义starter中的默认配置文件也打包 -->
<resources>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.yml</include>
<include>**/*.yaml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build>
</project>
<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">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.example</groupId>
<artifactId>custom-springboot-starter-demo</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<artifactId>test</artifactId>
<packaging>jar</packaging>
<name>test</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.example</groupId>
<artifactId>custom-starter</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
</dependencies>
</project>
package org.feng.config;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.AutoConfiguration;
import org.springframework.context.annotation.Bean;
/**
* 自动配置类：在META-INF中不做配置时，会抛出警告 <code>Application context not configured for this file</code>
*
* @version V1.0
*/
@AutoConfiguration
public class AppInfoConfiguration {
@Value("${app.url.baiDu}")
private String baiDuUrl;
public String getBaiDuUrl() {
return baiDuUrl;
}
public void setBaiDuUrl(String baiDuUrl) {
this.baiDuUrl = baiDuUrl;
}
@Bean
public AppUrl generateAppUrl() {
AppUrl appUrl = new AppUrl();
appUrl.setBaidu(baiDuUrl);
return appUrl;
}
}
