SpringBoot（注解）

Spring Boot 自动配置原理

最新推荐文章于 2025-09-30 11:00:57 发布

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最新推荐文章于 2025-09-30 11:00:57 发布 · 363 阅读

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1.解析主类—注解

import org.springframework.boot.Banner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
@SpringBootApplication
@ComponentScan(basePackages = "com.wangxing.springboot")
public class Springbootdemo1Application {
   
   
    public static void main(String[] args) {
   
   
  	SpringApplication.run(Springbootdemo1Application.class, args);
    }
}

@SpringBootApplication
源码:

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
   
    @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
      @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
   
   
........
}

1.@SpringBootApplication实际上它是一个复合注解。
虽然它的定义使用了多个注解，但实际上对于 SpringBoot 应用来说，重要的只有三个注解，这三个注解：

@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })

所以，如果我们使用上面三个注解作用在主类上整个 SpringBoot 应用依然可以与之前的启动类功能对等。

package com.wangxing.springboot.springbootdemo2;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.AutoConfigurationExcludeFilter;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.TypeExcludeFilter;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.FilterType;
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
   
    @ComponentScan.Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
        @ComponentScan.Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public class Springbootdemo2Application {
   
   
    public static void main(String[] args) {
   
   
        SpringApplication.run(Springbootdemo2Application.class, args);
    }
}

但每次都写三个注解显然过于繁琐，所以写一个 @SpringBootApplication 这样的一站式复合注解显然更方便些。
@SpringBootConfiguration注解 [创建配置类从而代替配置文件]
@SpringBootConfiguration注解中包含了@Configuration。
@Configuration–是 Spring JavaConfig 形式的 Spring IoC 容器的配置类使用的注解。既然 SpringBoot 应用骨子里就是一个 Spring 应用，那么，自然也需要加载某个 IoC 容器的配置，而 SpringBoot 社区推荐使用基于 JavaConfig 的配置形式，所以