public interface Lifecycle {
	    /**
     * 啟動(dòng)當(dāng)前組件，如果組件已經(jīng)在運(yùn)行，不應(yīng)該拋出異常，這樣將開(kāi)始信號(hào)傳播到應(yīng)用的所有組件中去。
     */
	void start();
	    /**
     * 通常以同步方式停止該組件，當(dāng)該方法執(zhí)行完成后，該組件會(huì)被完全停止。當(dāng)需要異步停止行為時(shí)，考慮實(shí)現(xiàn)SmartLifecycle和它的 stop(Runnable) 方法變體。 
	 注意，此停止通知在銷毀前不能保證到達(dá):
　　　　在常規(guī)關(guān)閉時(shí)，{@code Lifecycle} bean將首先收到一個(gè)停止通知，然后才傳播常規(guī)銷毀回調(diào);
　　　　在上下文的生命周期內(nèi)的刷新或中止時(shí)，只調(diào)用銷毀方法
　　　　對(duì)于容器，這將把停止信號(hào)傳播到應(yīng)用的所有組件
     */
	void stop();
	    /**
      *  檢查此組件是否正在運(yùn)行。
      *  1. 只有該方法返回false時(shí)，start方法才會(huì)被執(zhí)行。
      *  2. 只有該方法返回true時(shí)，stop(Runnable callback)或stop()方法才會(huì)被執(zhí)行。
      */
	boolean isRunning();
}

package com.morris.spring.demo.lifecycle;
import org.springframework.context.Lifecycle;
/**
 * 自定義Lifecycle
 */
public class MyLifecycle implements Lifecycle {
	private boolean isRunning;
	@Override
	public void start() {
		System.out.println("MyLifecycle start");
		isRunning = true;
	}
	@Override
	public void stop() {
		System.out.println("MyLifecycle stop");
		isRunning = false;
	}
	@Override
	public boolean isRunning() {
		return isRunning;
	}
}

public class LifecycleDemo {
	public static void main(String[] args) {
		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
		applicationContext.register(MyLifecycle.class);
		applicationContext.refresh();
	}
}

public class LifecycleDemo {
	public static void main(String[] args) {
		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
		applicationContext.register(MyLifecycle.class);
		applicationContext.refresh();
		applicationContext.start();
		applicationContext.stop();
	}
}

DEBUG main DefaultLifecycleProcessor:356 - Starting beans in phase 0
MyLifecycle start
DEBUG main DefaultLifecycleProcessor:188 - Successfully started bean 'myLifecycle'
DEBUG main DefaultLifecycleProcessor:369 - Stopping beans in phase 0
MyLifecycle stop
DEBUG main DefaultLifecycleProcessor:253 - Successfully stopped bean 'myLifecycle'

public interface SmartLifecycle extends Lifecycle, Phased {
	int DEFAULT_PHASE = Integer.MAX_VALUE;
	/**
      * 如果該`Lifecycle`類所在的上下文在調(diào)用`refresh`時(shí)，希望能夠自己自動(dòng)進(jìn)行回調(diào)，則返回`true`* ,
      * false的值表明組件打算通過(guò)顯式的start()調(diào)用來(lái)啟動(dòng)，類似于普通的Lifecycle實(shí)現(xiàn)。
     */
	default boolean isAutoStartup() {
		return true;
	}
	default void stop(Runnable callback) {
		stop();
		callback.run();
	}
	@Override
	default int getPhase() {
		return DEFAULT_PHASE;
	}
}

package com.morris.spring.demo.lifecycle;
import org.springframework.context.SmartLifecycle;
/**
 * 自定義SmartLifecycle
 */
public class MySmartLifecycle implements SmartLifecycle {
	private boolean isRunning;
	@Override
	public void start() {
		System.out.println("MyLifecycle start");
		isRunning = true;
	}
	@Override
	public void stop() {
		System.out.println("MyLifecycle stop");
		isRunning = false;
	}
	@Override
	public boolean isRunning() {
		return isRunning;
	}
}

package com.morris.spring.demo.lifecycle;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
/**
 * 演示SmartLifecycle
 */
public class SmartLifecycleDemo {
	public static void main(String[] args) {
		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
		applicationContext.register(MySmartLifecycle.class);
		applicationContext.refresh();
	}
}

DEBUG main DefaultListableBeanFactory:228 - Creating shared instance of singleton bean 'mySmartLifecycle'
DEBUG main DefaultLifecycleProcessor:357 - Starting beans in phase 2147483647
MyLifecycle start
DEBUG main DefaultLifecycleProcessor:189 - Successfully started bean 'mySmartLifecycle'

public void start() {
	// 獲取DefaultLifecycleProcessor
	/**
		 * @see DefaultLifecycleProcessor#start()
		 */
	getLifecycleProcessor().start();
	publishEvent(new ContextStartedEvent(this));
}

public void start() {
	startBeans(false);
	this.running = true;
}

protected void finishRefresh() {
	// Clear context-level resource caches (such as ASM metadata from scanning).
	clearResourceCaches();
	// Initialize lifecycle processor for this context.
	// 注入DefaultLifecycleProcessor
	initLifecycleProcessor();
	// Propagate refresh to lifecycle processor first.
	getLifecycleProcessor().onRefresh();
	// Publish the final event.
	publishEvent(new ContextRefreshedEvent(this));
	// Participate in LiveBeansView MBean, if active.
	LiveBeansView.registerApplicationContext(this);
}

public void onRefresh() {
	startBeans(true);
	this.running = true;
}

private void startBeans(boolean autoStartupOnly) {
	// 拿到容器中所有的Lifecycle
	Map<String, Lifecycle> lifecycleBeans = getLifecycleBeans();
	Map<Integer, LifecycleGroup> phases = new HashMap<>();
	lifecycleBeans.forEach((beanName, bean) -> {
		if (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) {
			// autoStartupOnly=false，表示調(diào)用的Lifecycle
			// autoStartupOnly=true，表示調(diào)用的SmartLifecycle
			int phase = getPhase(bean);
			// 根據(jù)phase進(jìn)行分組
			LifecycleGroup group = phases.get(phase);
			if (group == null) {
				group = new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly);
				phases.put(phase, group);
			}
			group.add(beanName, bean);
		}
	});
	if (!phases.isEmpty()) {
		List<Integer> keys = new ArrayList<>(phases.keySet());
		Collections.sort(keys);
		for (Integer key : keys) {
			// 調(diào)用start()
			phases.get(key).start();
		}
	}
}