【面试题-2】SpringBoot启动过程

标签：OLE   image   启动过程   tco   开启   tor   复合   power   inf   

SpringBoot 启动类中的1个核心注解

@SpringBootApplication

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package org.springframework.boot.autoconfigure;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.context.TypeExcludeFilter;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.core.annotation.AliasFor;

@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 {
    @AliasFor(
        annotation = EnableAutoConfiguration.class
    )
    Class<?>[] exclude() default {};

    @AliasFor(
        annotation = EnableAutoConfiguration.class
    )
    String[] excludeName() default {};

    @AliasFor(
        annotation = ComponentScan.class,
        attribute = "basePackages"
    )
    String[] scanBasePackages() default {};

    @AliasFor(
        annotation = ComponentScan.class,
        attribute = "basePackageClasses"
    )
    Class<?>[] scanBasePackageClasses() default {};

    @AliasFor(
        annotation = Configuration.class
    )
    boolean proxyBeanMethods() default true;
}

可以看到一个@SpringBootApplication注解里已经包含了1.@SpringBootConfiguration 该注解主要是将当前类作为一个JavaConfig本质上和普通的@Configuration没有区别
2.@ComponentScan，该注解会用于扫描Spring对应的组件，如果里面不设置值，则会默认从所在类的package进行扫描。所以一般启动类都放在根package下
3.@EnableAutoConfiguration，该注解标识可以自动配置，把所有符合自动配置条件的Bean定义加载到IOC容器

SpringBoot启动流程

1.当我们启动SpringBoot的时候，先动用启动类中的静态run方法

【面试题-2】SpringBoot启动过程

标签：OLE   image   启动过程   tco   开启   tor   复合   power   inf   

原文地址：https://www.cnblogs.com/LeeBoom/p/mian-shi-ti2springboot-qi-dong-guo-cheng.html