SpringBoot入口类

入口类的类名是根据项目名称生成的，我们的项目名称是my-spring-boot，故入口类的类名是项目名称+Application，即MySpringBootApplication.java。
入口类的代码很简单，代码如下：

package com.gs.bjy;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;


@SpringBootApplication
public class BjyMsApplication {
    public static void main(String[] args) {
        SpringApplication.run(BjyMsApplication.class, args);
    }
}

SpringBootApplication：是一个组合注解，包含@EnableAutoConfiguration、@ComponentScan和@SpringBootConfiguration三个注解，是项目启动注解。如果我们使用这三个注解，项目依旧可以启动起来，只是过于烦琐。因此，用@SpringBootApplication进行简化。
@SpringApplication.run：应用程序开始运行的方法。
提示:入口类需要放置在包的最外层，以便能够扫描到所有子包中的类。
@SpringBootApplication源码:

//
// 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.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 {};
}