[用Java编写Minecraft插件时,您可以创建一个事件监听器方法,并随意命名,但是您必须传入事件监听器的类,例如:
@EventListener
public void onPlayerJoin(PlayerJoinEvent event) {
// code here
}
我只是想知道,如果Bukkit API中的任何类都不知道该方法的名称,那么该方法如何在“幕后”执行?我希望我能很好地解释自己。谢谢
[注册实现Listener
的实例时,Bukkit将使用反射检查带有@EventHandler
批注和一个扩展了Event
的参数的类中的每个方法。它会存储在注册表中,并在事件发生时被调用。
编辑:您可能对下面的源代码感兴趣。 Source
@Override
@NotNull
public Map<Class<? extends Event>, Set<RegisteredListener>> createRegisteredListeners(@NotNull Listener listener, @NotNull final Plugin plugin) {
Validate.notNull(plugin, "Plugin can not be null");
Validate.notNull(listener, "Listener can not be null");
boolean useTimings = server.getPluginManager().useTimings();
Map<Class<? extends Event>, Set<RegisteredListener>> ret = new HashMap<Class<? extends Event>, Set<RegisteredListener>>();
Set<Method> methods;
try {
Method[] publicMethods = listener.getClass().getMethods();
Method[] privateMethods = listener.getClass().getDeclaredMethods();
methods = new HashSet<Method>(publicMethods.length + privateMethods.length, 1.0f);
for (Method method : publicMethods) {
methods.add(method);
}
for (Method method : privateMethods) {
methods.add(method);
}
} catch (NoClassDefFoundError e) {
plugin.getLogger().severe("Plugin " + plugin.getDescription().getFullName() + " has failed to register events for " + listener.getClass() + " because " + e.getMessage() + " does not exist.");
return ret;
}
for (final Method method : methods) {
final EventHandler eh = method.getAnnotation(EventHandler.class);
if (eh == null) continue;
// Do not register bridge or synthetic methods to avoid event duplication
// Fixes SPIGOT-893
if (method.isBridge() || method.isSynthetic()) {
continue;
}
final Class<?> checkClass;
if (method.getParameterTypes().length != 1 || !Event.class.isAssignableFrom(checkClass = method.getParameterTypes()[0])) {
plugin.getLogger().severe(plugin.getDescription().getFullName() + " attempted to register an invalid EventHandler method signature \"" + method.toGenericString() + "\" in " + listener.getClass());
continue;
}
final Class<? extends Event> eventClass = checkClass.asSubclass(Event.class);
method.setAccessible(true);
Set<RegisteredListener> eventSet = ret.get(eventClass);
if (eventSet == null) {
eventSet = new HashSet<RegisteredListener>();
ret.put(eventClass, eventSet);
}
for (Class<?> clazz = eventClass; Event.class.isAssignableFrom(clazz); clazz = clazz.getSuperclass()) {
// This loop checks for extending deprecated events
if (clazz.getAnnotation(Deprecated.class) != null) {
Warning warning = clazz.getAnnotation(Warning.class);
WarningState warningState = server.getWarningState();
if (!warningState.printFor(warning)) {
break;
}
plugin.getLogger().log(
Level.WARNING,
String.format(
"\"%s\" has registered a listener for %s on method \"%s\", but the event is Deprecated. \"%s\"; please notify the authors %s.",
plugin.getDescription().getFullName(),
clazz.getName(),
method.toGenericString(),
(warning != null && warning.reason().length() != 0) ? warning.reason() : "Server performance will be affected",
Arrays.toString(plugin.getDescription().getAuthors().toArray())),
warningState == WarningState.ON ? new AuthorNagException(null) : null);
break;
}
}
EventExecutor executor = new EventExecutor() {
@Override
public void execute(@NotNull Listener listener, @NotNull Event event) throws EventException {
try {
if (!eventClass.isAssignableFrom(event.getClass())) {
return;
}
method.invoke(listener, event);
} catch (InvocationTargetException ex) {
throw new EventException(ex.getCause());
} catch (Throwable t) {
throw new EventException(t);
}
}
};
if (useTimings) {
eventSet.add(new TimedRegisteredListener(listener, executor, eh.priority(), plugin, eh.ignoreCancelled()));
} else {
eventSet.add(new RegisteredListener(listener, executor, eh.priority(), plugin, eh.ignoreCancelled()));
}
}
return ret;
}