许多Spring Boot开发人员总是使用@Configuration，@EnableAutoConfiguration和@ComponentScan来标注它们的主类。 由于这些注释经常一起使用（特别是如果您遵循上述最佳实践），Spring Boot提供了一个方便的@SpringBootApplication替代方法。

@SpringBootApplication注释相当于同时使用@Configuration，@EnableAutoConfiguration和@ComponentScan及其默认属性（重复注解，SpringBoot是怎么处理的？）：

package com.example.myproject;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication /* same as */ //@Configuration //@EnableAutoConfiguration //@ComponentScanpublic class Application {    public static void main(String[] args) {        SpringApplication.run(Application.class, args);    }}

NOTE

@SpringBootApplication alias 关联了注解： @EnableAutoConfiguration和@ComponentScan的属性。

源码：

/* * Copyright 2012-2015 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */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.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;/** * Indicates a {@link Configuration configuration} class that declares one or more * {@link Bean @Bean} methods and also triggers {@link EnableAutoConfiguration * auto-configuration} and {@link ComponentScan component scanning}. This is a convenience * annotation that is equivalent to declaring {@code @Configuration}, * {@code @EnableAutoConfiguration} and {@code @ComponentScan}. * * @author Phillip Webb * @since 1.2.0 */@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Inherited@Configuration@EnableAutoConfiguration@ComponentScanpublic @interface SpringBootApplication {    /**     * Exclude specific auto-configuration classes such that they will never be applied.     * @return the classes to exclude     */    Class
     [] exclude() default {};}

所以说，你也可以直接自己定于注解，来封装一些常用的注解。

package com.restfiddle;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.autoconfigure.EnableAutoConfiguration;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;/** * Created by jack on 2017/3/23. * * @author jack * @date 2017/03/23 */@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Inherited@Configuration@EnableAutoConfiguration@ComponentScanpublic @interface RestBoot {    Class
     [] exclude() default {};}

代码中可以这样用：

/* * Copyright 2014 Ranjan Kumar * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package com.restfiddle;import org.springframework.boot.SpringApplication;/** * 应用入口类 main函数 *///@Configuration//@EnableAutoConfiguration//@ComponentScan({"com.restfiddle"})//@SpringBootApplication@RestBootpublic class RestFiddleApplication {    public RestFiddleApplication() {    }    public static void main(String[] args) throws Exception {        SpringApplication.run(RestFiddleApplication.class, args);    }}