<properties><java.version>1.8</java.version><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target></properties>

@SpringBootApplication
public class App {@Beanpublic Runnable createRunnable() {return () -> {System.out.println("spring boot is running");};}public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);context.getBean(Runnable.class).run();System.out.println(context.getBean(User.class));}
}

@ComponentScan
public class App2 {@Beanpublic Runnable createRunnable() {return () -> {System.out.println("spring boot is running");};}public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App2.class, args);context.getBean(Runnable.class).run();System.out.println(context.getBean(User.class));}
}

@ComponentScan
public class App2 {@Beanpublic Runnable createRunnable() {return () -> {System.out.println("spring boot is running");};}public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App2.class, args);context.getBean(Runnable.class).run();System.out.println(context.getBean(User.class));}
}

@ComponentScan
public class App3 {@Beanpublic Runnable createRunnable() {return () -> {System.out.println("spring boot is running");};}public static void main(String[] args) {// SpringApplication app = new SpringApplication(App3.class);SpringApplication app = new SpringApplication();Set<Object> sets = new HashSet<>();sets.add(App3.class);app.setSources(sets);ConfigurableApplicationContext context = app.run(App3.class, args);context.getBean(Runnable.class).run();System.out.println(context.getBean(User.class));}
}

短歌行
作者：曹操
对酒当歌，人生几何！
譬如朝露，去日苦多。
慨当以慷，忧思难忘。
何以解忧？唯有杜康。
青青子衿，悠悠我心。
但为君故，沉吟至今。
呦呦鹿鸣，食野之苹。
我有嘉宾，鼓瑟吹笙。
明明如月，何时可掇？
忧从中来，不可断绝。
越陌度阡，枉用相存。
契阔谈，心念旧恩。
月明星稀，乌鹊南飞。
绕树三匝，何枝可依？
山不厌高，海不厌深。
周公吐哺，天下归心。