Topic通配符规则

Topic通配符规则定义消息路由键与绑定键的模式匹配逻辑，实现灵活的多条件路由。

定义

Topic交换机使用两种通配符进行路由键匹配：*匹配恰好一个单词段，#匹配零个或多个单词段。路由键以点号.分隔形成层级结构的单词序列。

通配符语法

基础规则

匹配示例

绑定键: order.us.*
  匹配: order.us.created ✓
        order.us.updated ✓
  不匹配: order.eu.created ✗
          order.us.nyse.created ✗

绑定键: order.#
  匹配: order ✓
        order.us ✓
        order.us.created ✓
        order.us.nyse.pending ✓

绑定键: *.critical
  匹配: order.critical ✓
        payment.critical ✓
  不匹配: critical ✗（需要前面有一个单词段）
          order.high.critical ✗

完整示例

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import java.util.HashMap;
import java.util.Map;

public class TopicWildcardExample {
    private static final String EXCHANGE_NAME = "topic_logs";

    public static void main(String[] args) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        
        try (Connection connection = factory.newConnection();
             Channel channel = connection.createChannel()) {
            
            channel.exchangeDeclare(EXCHANGE_NAME, "topic", true);
            
            // 声明队列并绑定不同通配符模式
            channel.queueDeclare("queue_all", true, false, false, null);
            channel.queueDeclare("queue_us", true, false, false, null);
            channel.queueDeclare("queue_errors", true, false, false, null);
            channel.queueDeclare("queue_payments", true, false, false, null);
            
            // 通配符绑定示例
            channel.queueBind("queue_all", EXCHANGE_NAME, "#");              // 接收所有消息
            channel.queueBind("queue_us", EXCHANGE_NAME, "*.us.*");          // 匹配中间为us的三段路由键
            channel.queueBind("queue_errors", EXCHANGE_NAME, "*.error");     // 匹配以error结尾的两段路由键
            channel.queueBind("queue_payments", EXCHANGE_NAME, "payment.#"); // 匹配所有payment开头的消息
            
            System.out.println("Topic bindings configured");
            
            // 测试不同路由键的消息分发
            String[] testRoutingKeys = {
                "order.us.created",      // -> queue_all, queue_us
                "order.eu.created",      // -> queue_all
                "payment.error",         // -> queue_all, queue_errors
                "payment.us.refund",     // -> queue_all, queue_us, queue_payments
                "system.warning",        // -> queue_all
                "critical.error"         // -> queue_all, queue_errors
            };
            
            for (String routingKey : testRoutingKeys) {
                String message = "Test message for " + routingKey;
                channel.basicPublish(EXCHANGE_NAME, routingKey, null, 
                        message.getBytes("UTF-8"));
                System.out.println("Published: " + routingKey);
            }
        }
    }
}

消费者配置

import com.rabbitmq.client.*;

public class TopicConsumer {
    private static final String EXCHANGE_NAME = "topic_logs";

    public static void main(String[] args) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        
        channel.exchangeDeclare(EXCHANGE_NAME, "topic", true);
        
        // 使用临时队列接收特定模式的消息
        String queueName = channel.queueDeclare().getQueue();
        
        // 绑定通配符路由键
        channel.queueBind(queueName, EXCHANGE_NAME, "order.*.created");
        
        System.out.println("Waiting for order creation messages...");
        
        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            String routingKey = delivery.getEnvelope().getRoutingKey();
            System.out.println("[" + routingKey + "] " + message);
            channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
        };
        
        channel.basicConsume(queueName, false, deliverCallback, consumerTag -> {});
    }
}

注意事项

• #可匹配零个单词段，stock.#可匹配stock本身
• *必须匹配恰好一个单词段，stock.*不匹配stock本身
• 路由键单词段建议使用小写字母和数字，避免特殊字符导致匹配异常
• Topic交换机匹配性能随绑定数量增加而下降，建议控制绑定总数
• 通配符匹配是贪婪的，#会尽可能匹配更多单词段

要点总结

• *匹配恰好一个单词段，#匹配零个或多个单词段
• 路由键以点号分隔，形成层级结构便于通配符匹配
• #作为绑定键时接收所有消息，等效于Fanout交换机
• 通配符匹配性能随绑定数量增加而下降，需合理设计路由结构
• 适用于多条件过滤、主题分类、层级路由等灵活路由场景

文章存放路径：D:\git2\jwdev\articles\RABBITMQ\进阶\消息路由与绑定\Topic通配符规则.md