单例模式+观察者模式，60行代码简单实现事件总线。

我会带着你远行 2022-06-01 11:06 109阅读 0赞

# 单例模式+观察者模式，实现事件总线。 #

直接上代码：

import java.util.ArrayList;
    import java.util.List;
    /**
     * 消息通知
     * Created by zhouzhengwei on 2018/1/25.
     */
    public class MessageBus {
        private List<Callback> mObservers;
    
        private MessageBus(){
            mObservers = new ArrayList<>();
        }
        public static MessageBus getInstance(){
            return SingleEvent.INSTANCE.getInstance();
        }
    
        private static enum SingleEvent{
            INSTANCE;
            private MessageBus messageBus;
            private SingleEvent(){
                messageBus = new MessageBus();
            }
            public MessageBus getInstance(){
                return messageBus;
            }
        }
    
        //注册
        public void register(MessageBus.Callback callback){
            if (callback == null){
                return;
            }
            synchronized (this) {
                if (!mObservers.contains(callback)){
                    mObservers.add(callback);
                }
            }
        }
    
        //移除
        public synchronized void remove(MessageBus.Callback callback) {
            mObservers.remove(callback);
        }
    
        //发送消息
        public void send(String msg) {
            for (MessageBus.Callback observer : mObservers) {
                observer.excute(msg);
            }
        }
    
        interface Callback{
            public void excute(String msg);
        }
    
        public static void main(String[] arg){
            MessageBus messageBus = MessageBus.getInstance();
            MessageBus.Callback callback = new Callback() {
                @Override
                public void excute(String msg) {
                    System.out.print(msg);
                }
            };
            messageBus.register(callback);
            MessageBus.getInstance().send("6666666666");
        }