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EventBus is a publish/subscribe event bus optimized for Android .
/*
* Copyright (C) 2012 Markus Junginger, greenrobot (http://greenrobot.de)
*
* 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 de.greenrobot.event;
import android.util.Log;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
class SubscriberMethodFinder {
private static final String ON_EVENT_METHOD_NAME = "onEvent";
/*
* In newer class files, compilers may add methods. Those are called bridge or synthetic methods.
* EventBus must ignore both. There modifiers are not public but defined in the Java class file format:
* http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.6-200-A.1
*/
private static final int BRIDGE = 0x40;
private static final int SYNTHETIC = 0x1000;
private static final int MODIFIERS_IGNORE = Modifier.ABSTRACT | Modifier.STATIC | BRIDGE | SYNTHETIC;
private static final Map> methodCache = new HashMap>();
private final Map, Class> skipMethodVerificationForClasses;
SubscriberMethodFinder(List> skipMethodVerificationForClassesList) {
skipMethodVerificationForClasses = new ConcurrentHashMap, Class>();
if (skipMethodVerificationForClassesList != null) {
for (Class clazz : skipMethodVerificationForClassesList) {
skipMethodVerificationForClasses.put(clazz, clazz);
}
}
}
List findSubscriberMethods(Class subscriberClass) {
String key = subscriberClass.getName();
List subscriberMethods;
synchronized (methodCache) {
subscriberMethods = methodCache.get(key);
}
if (subscriberMethods != null) {
return subscriberMethods;
}
subscriberMethods = new ArrayList();
Class clazz = subscriberClass;
HashSet eventTypesFound = new HashSet();
StringBuilder methodKeyBuilder = new StringBuilder();
while (clazz != null) {
String name = clazz.getName();
if (name.startsWith("java.") || name.startsWith("javax.") || name.startsWith("android.")) {
// Skip system classes, this just degrades performance
break;
}
// Starting with EventBus 2.2 we enforced methods to be public (might change with annotations again)
Method[] methods = clazz.getDeclaredMethods();
for (Method method : methods) {
String methodName = method.getName();
if (methodName.startsWith(ON_EVENT_METHOD_NAME)) {
int modifiers = method.getModifiers();
if ((modifiers & Modifier.PUBLIC) != 0 && (modifiers & MODIFIERS_IGNORE) == 0) {
Class[] parameterTypes = method.getParameterTypes();
if (parameterTypes.length == 1) {
String modifierString = methodName.substring(ON_EVENT_METHOD_NAME.length());
ThreadMode threadMode;
if (modifierString.length() == 0) {
threadMode = ThreadMode.PostThread;
} else if (modifierString.equals("MainThread")) {
threadMode = ThreadMode.MainThread;
} else if (modifierString.equals("BackgroundThread")) {
threadMode = ThreadMode.BackgroundThread;
} else if (modifierString.equals("Async")) {
threadMode = ThreadMode.Async;
} else {
if (skipMethodVerificationForClasses.containsKey(clazz)) {
continue;
} else {
throw new EventBusException("Illegal onEvent method, check for typos: " + method);
}
}
Class eventType = parameterTypes[0];
methodKeyBuilder.setLength(0);
methodKeyBuilder.append(methodName);
methodKeyBuilder.append('>').append(eventType.getName());
String methodKey = methodKeyBuilder.toString();
if (eventTypesFound.add(methodKey)) {
// Only add if not already found in a sub class
subscriberMethods.add(new SubscriberMethod(method, threadMode, eventType));
}
}
} else if (!skipMethodVerificationForClasses.containsKey(clazz)) {
Log.d(EventBus.TAG, "Skipping method (not public, static or abstract): " + clazz + "."
+ methodName);
}
}
}
clazz = clazz.getSuperclass();
}
if (subscriberMethods.isEmpty()) {
throw new EventBusException("Subscriber " + subscriberClass + " has no public methods called "
+ ON_EVENT_METHOD_NAME);
} else {
synchronized (methodCache) {
methodCache.put(key, subscriberMethods);
}
return subscriberMethods;
}
}
static void clearCaches() {
synchronized (methodCache) {
methodCache.clear();
}
}
}