交换机 Exchange

src/main/java/io/jiulinxiri/rabbitmq/five/EmitLog.java

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+package io.jiulinxiri.rabbitmq.five;
+
+import com.rabbitmq.client.Channel;
+import io.jiulinxiri.rabbitmq.utils.RabbitMqUtils;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Scanner;
+
+/**
+ * 生产者
+ */
+public class EmitLog {
+    public static final String EXCHANGE_NAME = "logs";
+
+    public static void main(String[] args) throws Exception {
+        Channel channel = RabbitMqUtils.getChannel();
+
+        // 声明交换机
+//        channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
+        Scanner scanner = new Scanner(System.in);
+        while (scanner.hasNext()) {
+            String message = scanner.next();
+            channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes(StandardCharsets.UTF_8));
+            System.out.println("生产者发送消息: " + message);
+        }
+    }
+}

src/main/java/io/jiulinxiri/rabbitmq/five/README.md

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+---
+gitea: none
+include_toc: true
+---
+
+## 交换机Exchanges
+### Exchange 概念
+RabbitMQ 消息传递模型的核心思想是:  **生产者生产的消息从不会直接发送到队列**。实际上，通常生产
+者甚至都不知道这些消息传递传递到了哪些队列中。
+
+相反，**生产者只能将消息发送到交换机(exchange)**，交换机工作的内容非常简单，一方面它接收来
+自生产者的消息，另一方面将它们推入队列。交换机必须确切知道如何处理收到的消息。是应该把这些消
+息放到特定队列还是说把他们到许多队列中还是说应该丢弃它们。这就的由交换机的类型来决定。
+
+<img alt="Exchange" src="https://vip1.loli.io/2021/11/30/8P1NCc4gqWbBSDy.png" title="Exchange" width="300px"/>
+
+### Exchange 的类型
+交换机有以下的四种类型
+* 直接(direct)
+* 主题(topic) 
+* 标题(headers)
+* 扇出(fanout) [发布/订阅]
+
+#### 无名 exchange
+```java
+channel.basicPublish("", queueName, null, message.getBytes());
+```
+exchange的名称为空字符串表示默认或无名称交换机
+
+### 临时队列
+断开消费者连接，能自动删除的队列。临时队列没有进行持久化的队列。
+<img alt="754ueDFzNOZgyA3" src="https://vip2.loli.io/2021/11/30/754ueDFzNOZgyA3.png" width="400"/>
+
+```java
+// 创建临时队列的方式
+String queueName = channel.queueDeclare().getQueue();
+```
+
+### 绑定(bindings)
+binding 其实是  exchange 和 queue 之间的桥梁，它告诉我们  exchange 和那个队
+列进行了绑定关系。比如说下面这张图告诉我们的就是  X 与  Q1 和 Q2 进行了绑定
+
+<img alt="qKJkT5ec4pYzDmQ" src="https://vip1.loli.io/2021/11/30/qKJkT5ec4pYzDmQ.png" width="300px"/>
+
+### Fanout
+发布订阅模式，将接收到的所有消息广播到它知道的所有队列中
+
+#### Fanout 实战
+<img alt="Vt8fjZL4QgeR69S" src="https://vip1.loli.io/2021/11/30/Vt8fjZL4QgeR69S.png" width="400"/>

src/main/java/io/jiulinxiri/rabbitmq/five/ReceiveLogs01.java

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+package io.jiulinxiri.rabbitmq.five;
+
+import com.rabbitmq.client.CancelCallback;
+import com.rabbitmq.client.Channel;
+import com.rabbitmq.client.DeliverCallback;
+import io.jiulinxiri.rabbitmq.utils.RabbitMqUtils;
+
+public class ReceiveLogs01 {
+    public static final String EXCHANGE_NAME = "logs";
+
+    public static void main(String[] args) throws Exception {
+        Channel channel = RabbitMqUtils.getChannel();
+
+        // 声明交换机
+        channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
+
+        // 声明临时队列
+        String queueName = channel.queueDeclare().getQueue();
+
+        // 绑定交换机与队列
+        channel.queueBind(queueName, EXCHANGE_NAME, "");
+        System.out.println("等待接收消息，接收到的消息打印到屏幕上...");
+
+        DeliverCallback ackCallback = (consumerTag, message) -> {
+            System.out.println("ReceiveLogs01 控制太打印接收到的消息：" + new String(message.getBody(), "utf-8"));
+        };
+
+        CancelCallback cancelCallback = consumerTag -> {};
+
+        // 消费消息
+        channel.basicConsume(queueName, true, ackCallback, cancelCallback);
+    }
+}

src/main/java/io/jiulinxiri/rabbitmq/five/ReceiveLogs02.java

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+package io.jiulinxiri.rabbitmq.five;
+
+import com.rabbitmq.client.CancelCallback;
+import com.rabbitmq.client.Channel;
+import com.rabbitmq.client.DeliverCallback;
+import io.jiulinxiri.rabbitmq.utils.RabbitMqUtils;
+
+public class ReceiveLogs02 {
+    public static final String EXCHANGE_NAME = "logs";
+
+    public static void main(String[] args) throws Exception {
+        Channel channel = RabbitMqUtils.getChannel();
+
+        // 声明交换机
+        channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
+
+        // 声明临时队列
+        String queueName = channel.queueDeclare().getQueue();
+
+        // 绑定交换机与队列
+        channel.queueBind(queueName, EXCHANGE_NAME, "");
+        System.out.println("等待接收消息，接收到的消息打印到屏幕上...");
+
+        DeliverCallback ackCallback = (consumerTag, message) -> {
+            System.out.println("ReceiveLogs02 控制太打印接收到的消息：" + new String(message.getBody(), "utf-8"));
+        };
+
+        CancelCallback cancelCallback = consumerTag -> {};
+
+        // 消费消息
+        channel.basicConsume(queueName, true, ackCallback, cancelCallback);
+    }
+}