@SpringBootConfiguration继承自@Configuration，二者功能也一致，标注当前类是配置类，
并会将当前类内声明的一个或多个以@Bean注解标记的方法的实例纳入到spring容器中，并且实例名就是方法名。

如下所示：
我定义了一个配置类

package com.lhkj.pluto.config;

import java.util.HashMap;
import java.util.Map;

import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;

@SpringBootConfiguration
public class Config {
    @Bean
    public Map createMap(){
        Map map = new HashMap();
        map.put("username","gxz");
        map.put("age",27);
        return map;
    }
}

在main方法中，可以直接这样使用：

package com.lhkj.pluto;

import java.util.Map;
import java.util.concurrent.TimeUnit;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.embedded.EmbeddedServletContainerFactory;
import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.lhkj.pluto.user.entity.User;



/*
 * 发现@SpringBootApplication是一个复合注解，
 * 包括@ComponentScan，和@SpringBootConfiguration，@EnableAutoConfiguration
 * 
 */

@RestController
@SpringBootApplication
public class App 
{   
    
    @RequestMapping(value="/hello")
    public String Hello(){
        return "hello";
    }
    
    
    @Bean
    public Runnable createRunnable() {
        return () -> System.out.println("spring boot is running");
    }

    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
        ConfigurableApplicationContext context = SpringApplication.run(App.class, args);
        context.getBean(Runnable.class).run();
        System.out.println(context.getBean(User.class));
        Map map = (Map) context.getBean("createMap");   //注意这里直接获取到这个方法bean
        int age = (int) map.get("age");
        System.out.println("age=="+age);
    }
    
    
    @Bean
    public EmbeddedServletContainerFactory servletFactory(){
        TomcatEmbeddedServletContainerFactory tomcatFactory = 
                new TomcatEmbeddedServletContainerFactory();
        //tomcatFactory.setPort(8011);
        tomcatFactory.setSessionTimeout(10,TimeUnit.SECONDS);
        return tomcatFactory;
        
    }
}