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自定义SpringBoot的自动配置

news 2025/8/25 12:32:32

一.前言

SpringBoot通过自动配置实现了开箱即用的功能，极大方便了项目的开发，参照它的思路，我们是否也可以实现一个自定义的自动配置呢。

二.实现思路

1.自定义两个自动配置类

    @Configurationstatic class AutoConfiguration1{@Beanpublic Bean1 Bean1(){return new Bean1();}}

    @Configurationstatic class AutoConfiguration2{@Beanpublic Bean2 Bean2(){return new Bean2();}}

2.spring.factories文件配置

其中有一个键为org.springframework.boot.autoconfigure.EnableAutoConfiguration，SpringBoot中通过这个键值来配置自定义的类

com.example.springdemo.demos.a04.TestAutoConfiguration$MyImportSelector=\
com.example.springdemo.demos.a04.TestAutoConfiguration.AutoConfiguration1,\
com.example.springdemo.demos.a04.TestAutoConfiguration.AutoConfiguration2org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.example.springdemo.demos.a07.TestMyBoot.AutoConfiguration1,\
com.example.springdemo.demos.a07.TestMyBoot.AutoConfiguration2

3.在自定义的自动配置类上加@Import(AutoConfigurationImportSelector.class)

SpringBoot是通过这个导入类导入自动配置文件的

    @Configuration@Import(AutoConfigurationImportSelector.class)static  class Config{}

进入AutoConfigurationImportSelector类，粗略看下实现原理

可以看到getAutoConfigurationEntry方法，获取配置。

点开getCandidateConfigurations方法可以看到具体实现

里面也是通过SpringFactoriesLoader.loadFactoryNames(）加载配置文件。

打开this.getSpringFactoriesLoaderFactoryClass()可以看到它的加载的类EnableAutoConfiguration

者也是为什么要在配置类文件里面把自定义的配置类的键值配置为EnableAutoConfiguration的原因，只有这样在配合AutoConfigurationImportSelector便可以使用SpringBoot的自动配置配置我们的自定义类。

4.实战

package com.example.springdemo.demos.a07;import org.springframework.boot.autoconfigure.AutoConfigurationImportSelector;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.DeferredImportSelector;
import org.springframework.context.annotation.Import;
import org.springframework.core.io.support.SpringFactoriesLoader;
import org.springframework.core.type.AnnotationMetadata;/*** @author zhou* @version 1.0* @description TODO* @date 2025/8/24 16:11*/
public class TestMyBoot {public static void main(String[] args) {AnnotationConfigServletWebServerApplicationContext context = new AnnotationConfigServletWebServerApplicationContext();context.registerBean("config", Config.class);context.refresh();for(String name : context.getBeanDefinitionNames()){String resource = context.getBeanDefinition(name).getResourceDescription();if(resource != null){System.out.println(name + "来源："+resource);}}context.close();}@Configuration@Import(AutoConfigurationImportSelector.class)static  class Config{}/*static class MyImportSelector implements DeferredImportSelector{@Overridepublic String[] selectImports(AnnotationMetadata importingClassMetadata) {return SpringFactoriesLoader.loadFactoryNames(MyImportSelector.class,null).toArray(new String[0]);}}*/@Configurationstatic class AutoConfiguration1{@Beanpublic Bean1 Bean1(){return new Bean1();}}@Configurationstatic class AutoConfiguration2{@Beanpublic Bean2 Bean2(){return new Bean2();}}static class Bean1{}static class Bean2{}}

测试结果：