SpringBoot的条件装配原理及实现思路

static class MyConditional1 implements Condition {
        @Override
        public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
            return ClassUtils.isPresent("com.alibaba.druid.pool.DruidDataSource", null);
        }
    }

 static class MyConditional2 implements Condition {
        @Override
        public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
            return !ClassUtils.isPresent("com.alibaba.druid.pool.DruidDataSource", null);
        }
    }

    @Configuration
    @Conditional(MyConditional1.class)
    static class AutoConfiguration1{
        @Bean
        public Bean1 Bean1(){
            return new Bean1();
        }
    }
    @Configuration
    @Conditional(MyConditional2.class)
    static class AutoConfiguration2{
        @Bean
        public Bean2 Bean2(){
            return new Bean2();
        }
    }
    static class Bean1{
    }
    static class Bean2{
    }

package com.example.springdemo.demos.a08;
import org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration;
import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext;
import org.springframework.context.annotation.*;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.util.ClassUtils;
/**
 * @author zhou
 * @version 1.0
 * @description TODO
 * @date 2025/8/24 16:11
 */
public class TestMyConditional {
    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(MyImportSelector.class)
    static  class Config{
    }
    static class MyImportSelector implements DeferredImportSelector{
        @Override
        public String[] selectImports(AnnotationMetadata importingClassMetadata) {
            return new String[]{AutoConfiguration1.class.getName(),AutoConfiguration2.class.getName(), ServletWebServerFactoryAutoConfiguration.class.getName()};
        }
    }
    static class MyConditional1 implements Condition {
        @Override
        public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
            return ClassUtils.isPresent("com.alibaba.druid.pool.DruidDataSource", null);
        }
    }
    static class MyConditional2 implements Condition {
        @Override
        public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
            return !ClassUtils.isPresent("com.alibaba.druid.pool.DruidDataSource", null);
        }
    }
    @Configuration
    @Conditional(MyConditional1.class)
    static class AutoConfiguration1{
        @Bean
        public Bean1 Bean1(){
            return new Bean1();
        }
    }
    @Configuration
    @Conditional(MyConditional2.class)
    static class AutoConfiguration2{
        @Bean
        public Bean2 Bean2(){
            return new Bean2();
        }
    }
    static class Bean1{
    }
    static class Bean2{
    }
}