public final class LifecycleSupport {
public LifecycleSupport(Lifecycle lifecycle) {
super();
this.lifecycle = lifecycle;
}
private LifecycleListener listeners[] = new LifecycleListener[0];
public void addLifecycleListener(LifecycleListener listener) { //向listeners添加监听器
synchronized (listeners) {
LifecycleListener results[] =
new LifecycleListener[listeners.length + 1];
for (int i = 0; i < listeners.length; i++)
results[i] = listeners[i];
results[listeners.length] = listener;
listeners = results;
}
}
public void fireLifecycleEvent(String type, Object data) {//群发事件给监听器
LifecycleEvent event = new LifecycleEvent(lifecycle, type, data);
LifecycleListener interested[] = null;
synchronized (listeners) {
interested = (LifecycleListener[]) listeners.clone();
}
for (int i = 0; i < interested.length; i++)
interested[i].lifecycleEvent(event);//发送组件生命周期事件。
}
}
先看构造方法，传入一个lifecycle，因为每个组件都实现了lifecycle，所以这里传入的实际上是一个组件，即每个组件都有一个LifecycleSupport与之关联，当要在组件中添加一个监听器的时候，实际上是添加进工具类LifecycleSupport的一个监听器数组listeners中，当要发送一个组件生命周期的事件时，工具类就会遍历监听器数组，然后再一个一个的发送事件。这里需要先实现我们自己的监听器类并且添加进我们需要监听的组件当中。实现监听器类只要实现LifecycleListener接口就行，这个接口只有一个方法：
[java]
public interface LifecycleListener {
public void lifecycleEvent(LifecycleEvent event);
}
我们需要做的就是实现LifecycleListener接口来拥有自己的监听器，在lifecycleEvent方法里写自己监听到事件后该做的事情，然后添加进要监听的组件就行，比如当我们要看StandardServer是否启动了，在上面StandardServer的start方法有一句这样的代码：lifecycle.fireLifecycleEvent(START_EVENT, null);即发送StandardServer启动的事件给跟它关联的监听器。接下来回到一开始，当server启动后，接着启动它的子组件service，即调用StandardService的start方法，这个方法跟StandardServer的start方法差不多，只是启动了连接器和容器，连接器的start方法在前面的文章已经讲过了，主要是启动了n个处理器HttpProcessor组件。顶级容器是StandardEngine，它的start方法仅仅调用了父类ContainerBase的start方法，下面看ContainerBase的start方法：
public synchronized void start() throws LifecycleException {
// Validate and update our current component state
if (started)
throw new LifecycleException
(sm.getString("containerBase.alreadyStarted", logName()));
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);
addDefaultMapper(this.mapperClass);
started = true; www.2cto.com
// Start our subordinate components, if any
if ((loader != null) && (loader instanceof Lifecycle)) //启动所有其他的组件
((Lifecycle) loader).start();
if ((logger != null) && (logger instanceof Lifecycle))
((Lifecycle) logger).start();
if ((manager != null) && (manager instanceof Lifecycle))
((Lifecycle) manager).start();
if ((cluster != null) && (cluster instanceof Lifecycle))
((Lifecycle) cluster).start();
if ((realm != null) && (realm instanceof Lifecycle))
((Lifecycle) realm).start();
if ((resources != null) && (resources instanceof Lifecycle))
((Lifecycle) resources).start();
// Start our Mappers, if any
Mapper mappers[] = findMappers();
for (int i = 0; i < mappers.length; i++) {
if (mappers[i] instanceof Lifecycle)
((Lifecycle) mappers[i]).start();
}
// Start our child containers, if any
Container children[] = findChildren();
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