聊聊logback的ShutdownHook

序

本文主要研究一下logback的ShutdownHook

ShutdownHook

ch/qos/logback/core/hook/ShutdownHook.java

/*** Interface describing a logback shutdown hook implementation* * @author Mike Reinhold*/
public interface ShutdownHook extends Runnable, ContextAware {
}

ShutdownHook接口继承了Runnable、ContextAware接口

ShutdownHookBase

ch/qos/logback/core/hook/ShutdownHookBase.java

/*** Base class for classes implementing a Logback ShutdownHook via extension** @author Mike Reinhold*/
public abstract class ShutdownHookBase extends ContextAwareBase implements ShutdownHook {public ShutdownHookBase() {}/*** Default method for stopping the Logback context*/protected void stop() {addInfo("Logback context being closed via shutdown hook");Context hookContext = getContext();if (hookContext instanceof ContextBase) {ContextBase context = (ContextBase) hookContext;context.stop();}}
}

ShutdownHookBase继承了ContextAwareBase，声明实现ShutdownHook，它提供了一个stop方法，用于关闭ContextBase

DelayingShutdownHook

ch/qos/logback/core/hook/DelayingShutdownHook.java

/*** ShutdownHook implementation that stops the Logback context after a specified* delay.  The default delay is 0 ms (zero).** @author Mike Reinhold*/
public class DelayingShutdownHook extends ShutdownHookBase {/*** The default is no delay before shutdown.*/public static final Duration DEFAULT_DELAY = Duration.buildByMilliseconds(0);/*** The delay in milliseconds before the ShutdownHook stops the logback context*/private Duration delay = DEFAULT_DELAY;public DelayingShutdownHook() {}public Duration getDelay() {return delay;}/*** The duration to wait before shutting down the current logback context.** @param delay*/public void setDelay(Duration delay) {this.delay = delay;}public void run() {addInfo("Sleeping for "+delay);try {Thread.sleep(delay.getMilliseconds());} catch (InterruptedException e) {}super.stop();}
}

DelayingShutdownHook继承了ShutdownHookBase，其run方法先sleep指定的delay，然后执行stop方法

示例

<configuration debug="false"><shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook"><delay>10</delay></shutdownHook><appender name="A" class="ch.qos.logback.core.read.ListAppender"/><root level="DEBUG"><appender-ref ref="A" /></root></configuration>

小结

logback的ShutdownHook接口继承了Runnable、ContextAware接口，它有一个抽象类ShutdownHookBase提供了一个stop方法，用于关闭ContextBase，它的子类为DelayingShutdownHook，可以延迟指定时间再关闭ContextBase。