统一消息系统

        // 定义消息结构体
        public class Message {
          private String topic;
          private String content;

          public Message(String topic, String content) {
            this.topic = topic;
            this.content = content;
          }

          public String getTopic() {
            return topic;
          }

          public String getContent() {
            return content;
          }
        }

        // 模拟消息队列
        import java.util.HashMap;
        import java.util.Map;

        public class MessageQueue {
          private Map> queues = new HashMap<>();

          public void publish(Message message) {
            String topic = message.getTopic();
            if (!queues.containsKey(topic)) {
              queues.put(topic, new LinkedList<>());
            }
            queues.get(topic).add(message);
          }

          public List subscribe(String topic) {
            return queues.getOrDefault(topic, new LinkedList<>());
          }
        }

        // 消费者示例
        public class Consumer implements Runnable {
          private MessageQueue queue;
          private String topic;

          public Consumer(MessageQueue queue, String topic) {
            this.queue = queue;
            this.topic = topic;
          }

          @Override
          public void run() {
            while (true) {
              List messages = queue.subscribe(topic);
              for (Message msg : messages) {
                System.out.println("Received: " + msg.getContent());
              }
            }
          }
        }