001/* 002 * Copyright 2002-2014 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.messaging.support; 018 019import java.util.Collections; 020import java.util.Set; 021import java.util.concurrent.CopyOnWriteArraySet; 022 023import org.springframework.messaging.MessageHandler; 024import org.springframework.messaging.SubscribableChannel; 025 026/** 027 * Abstract base class for {@link SubscribableChannel} implementations. 028 * 029 * @author Rossen Stoyanchev 030 * @since 4.0 031 */ 032public abstract class AbstractSubscribableChannel extends AbstractMessageChannel implements SubscribableChannel { 033 034 private final Set<MessageHandler> handlers = new CopyOnWriteArraySet<MessageHandler>(); 035 036 037 public Set<MessageHandler> getSubscribers() { 038 return Collections.<MessageHandler>unmodifiableSet(this.handlers); 039 } 040 041 public boolean hasSubscription(MessageHandler handler) { 042 return this.handlers.contains(handler); 043 } 044 045 @Override 046 public boolean subscribe(MessageHandler handler) { 047 boolean result = this.handlers.add(handler); 048 if (result) { 049 if (logger.isDebugEnabled()) { 050 logger.debug(getBeanName() + " added " + handler); 051 } 052 } 053 return result; 054 } 055 056 @Override 057 public boolean unsubscribe(MessageHandler handler) { 058 boolean result = this.handlers.remove(handler); 059 if (result) { 060 if (logger.isDebugEnabled()) { 061 logger.debug(getBeanName() + " removed " + handler); 062 } 063 } 064 return result; 065 } 066 067}