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 /*
  * Copyright (C) 2007 The Guava Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.common.eventbus;
A HandlerFindingStrategy for collecting all event handler methods that are marked with the Subscribe annotation.

Author(s):
Cliff Biffle
This implementation finds all methods marked with a Subscribe annotation.
  public Multimap<Class<?>, EventHandlerfindAllHandlers(Object listener) {
    Multimap<Class<?>, EventHandlermethodsInListener =
        HashMultimap.create();
    Class clazz = listener.getClass();
    while (clazz != null) {
      for (Method method : clazz.getMethods()) {
        Subscribe annotation = method.getAnnotation(Subscribe.class);
        if (annotation != null) {
          Class<?>[] parameterTypes = method.getParameterTypes();
          if (parameterTypes.length != 1) {
            throw new IllegalArgumentException(
                "Method " + method + " has @Subscribe annotation, but requires " +
                parameterTypes.length + " arguments.  Event handler methods " +
                "must require a single argument.");
          }
          Class<?> eventType = parameterTypes[0];
          EventHandler handler = makeHandler(listenermethod);
          methodsInListener.put(eventTypehandler);
        }
      }
      clazz = clazz.getSuperclass();
    }
    return methodsInListener;
  }

  
Creates an EventHandler for subsequently calling method on listener. Selects an EventHandler implementation based on the annotations on method.

Parameters:
listener object bearing the event handler method.
method the event handler method to wrap in an EventHandler.
Returns:
an EventHandler that will call method on listener when invoked.
  private static EventHandler makeHandler(Object listenerMethod method) {
    EventHandler wrapper;
    if (methodIsDeclaredThreadSafe(method)) {
      wrapper = new EventHandler(listenermethod);
    } else {
      wrapper = new SynchronizedEventHandler(listenermethod);
    }
    return wrapper;
  }

  
Checks whether method is thread-safe, as indicated by the AllowConcurrentEvents annotation.

Parameters:
method handler method to check.
Returns:
true if handler is marked as thread-safe, false otherwise.
  private static boolean methodIsDeclaredThreadSafe(Method method) {
    return method.getAnnotation(AllowConcurrentEvents.class) != null;
  }
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