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本篇内容主要讲解“nacos config的EventDispatcher是什么 ”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“nacos config的EventDispatcher是什么 ”吧!
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本文主要研究一下nacos config的EventDispatcher
nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/utils/event/EventDispatcher.java
public class EventDispatcher {
/**
* add event listener
*/
static public void addEventListener(AbstractEventListener listener) {
for (Class type : listener.interest()) {
getEntry(type).listeners.addIfAbsent(listener);
}
}
/**
* fire event, notify listeners.
*/
static public void fireEvent(Event event) {
if (null == event) {
throw new IllegalArgumentException();
}
for (AbstractEventListener listener : getEntry(event.getClass()).listeners) {
try {
listener.onEvent(event);
} catch (Exception e) {
log.error(e.toString(), e);
}
}
}
/**
* For only test purpose
*/
static public void clear() {
LISTENER_HUB.clear();
}
/**
* get event listener for eventType. Add Entry if not exist.
*/
static Entry getEntry(Class eventType) {
for (; ; ) {
for (Entry entry : LISTENER_HUB) {
if (entry.eventType == eventType) {
return entry;
}
}
Entry tmp = new Entry(eventType);
/**
* false means already exists
*/
if (LISTENER_HUB.addIfAbsent(tmp)) {
return tmp;
}
}
}
//......
static private final Logger log = LoggerFactory.getLogger(EventDispatcher.class);
static final CopyOnWriteArrayList LISTENER_HUB = new CopyOnWriteArrayList();
public interface Event {
}
//......
} EventDispatcher定义了addEventListener、fireEvent、clear方法；addEventListener会添加listener到Entry；fireEvent会遍历指定event的listener然后回调其onEvent方法；clear会清空整个LISTENER_HUB
nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/utils/event/EventDispatcher.java
static private class Entry {
final Class eventType;
final CopyOnWriteArrayList listeners;
Entry(Class type) {
eventType = type;
listeners = new CopyOnWriteArrayList();
}
@Override
public boolean equals(Object obj) {
if (null == obj || obj.getClass() != getClass()) {
return false;
}
if (this == obj) {
return true;
}
return eventType == ((Entry)obj).eventType;
}
@Override
public int hashCode() {
return super.hashCode();
}
} Entry有个eventType属性以及AbstractEventListener类型的listener集合
nacos-1.1.3/config/src/main/java/com/alibaba/nacos/config/server/utils/event/EventDispatcher.java
static public abstract class AbstractEventListener {
public AbstractEventListener() {
/**
* automatic register
*/
EventDispatcher.addEventListener(this);
}
/**
* 感兴趣的事件列表
*
* @return event list
*/
abstract public List> interest();
/**
* 处理事件
*
* @param event event
*/
abstract public void onEvent(Event event);
} AbstractEventListener定义了interest、onEvent方法
EventDispatcher定义了addEventListener、fireEvent、clear方法；addEventListener会添加listener到Entry；fireEvent会遍历指定event的listener然后回调其onEvent方法；clear会清空整个LISTENER_HUB
到此，相信大家对“nacos config的EventDispatcher是什么 ”有了更深的了解，不妨来实际操作一番吧！这里是创新互联网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！