RabbitMQ 中的交换机类型有哪些？

Question

Accepted Answer

RabbitMQ 有几种 **exchange 类型**，它们决定了消息如何路由到队列 — **direct**、**topic**、**fanout** 和 **headers**。理解它们对于 RabbitMQ 的灵活路由至关重要，这使得不同的消息传递模式成为可能。

## 交换机类型

```text
DIRECT → routes by an EXACT routing key match:
  → message routing key = queue binding key → delivered to that queue
  → for: routing to specific queues by a key (e.g. route by severity, type)
FANOUT → broadcasts to ALL bound queues (ignores routing key):
  → every queue bound to the exchange gets the message → PUB/SUB (one-to-many)
  → for: broadcasting events to all interested consumers
TOPIC → routes by PATTERN matching on the routing key (wildcards):
  → routing keys like "order.created", "order.*", "*.error" → flexible pattern routing
  → for: routing by topics/categories with wildcards (flexible pub/sub)
HEADERS → routes by message HEADER attributes (not the routing key) → less common
```

## 示例

```text
DIRECT → routing key "error" → only the queue bound with "error" gets it
FANOUT → every bound queue gets every message (broadcast)
TOPIC → "logs.error.payment" matches bindings "logs.#", "logs.error.*", "*.*.payment"
→ choose the exchange type for the routing pattern you need
```

## 交换机类型为什么重要

```text
✓ FLEXIBLE ROUTING → different types enable different patterns (direct delivery, broadcast,
  pattern-based, header-based) → RabbitMQ's powerful routing
✓ choose based on the pattern: specific routing (direct), broadcast (fanout), flexible
  topics (topic)
→ exchange types are central to how RabbitMQ routes messages flexibly
```

## 为什么这很重要

理解交换机类型很有价值，因为它们是 **RabbitMQ 灵活路由的核心** — 这是一个定义性特性 — 因此这是重要的 RabbitMQ 知识。

交换机类型决定了消息如何路由到队列，理解它们是使用 RabbitMQ 路由功能的关键。

理解 **exchange 类型** — **direct**（通过确切的 routing key 匹配进行路由，用于按键路由到特定队列）、**fanout**（广播到所有绑定的队列，忽略 routing key，用于发布/订阅一对多）、**topic**（通过 routing key 上带有通配符的模式匹配进行路由，用于灵活的主题/类别路由）和 **headers**（通过消息头属性进行路由，较少使用）— 涵盖了启用不同消息传递模式的路由选项。

理解 **示例**（direct 将消息传递到匹配的键所在的队列，fanout 广播到所有队列，topic 匹配如