RabbitMQ 实验消费原始队列消息， 拒绝（reject）投递死信交换机过程

如果你想通过 RabbitMQ 的死信队列功能实现消费者拒绝消息投递到死信交换机的行为，你可以按照以下步骤操作：

1. 创建原始队列，并将其绑定到一个交换机上：

export RABBITMQ_SERVER=127.0.0.1
export RABBITMQ_PORT=5672   
export RABBITMQ_USER=mingcai     
export RABBITMQ_PASSWORD=password

rabbitmqadmin list exchanges
rabbitmqadmin declare queue name=my_queue durable=true
rabbitmqadmin declare exchange name=my_exchange type=direct
rabbitmqadmin declare binding source=my_exchange destination=my_queue routing_key=my_routing_key

2. 创建死信交换机和死信队列，并将死信队列绑定到死信交换机：

rabbitmqadmin declare exchange name=my_dlx type=direct
rabbitmqadmin declare queue name=my_dlq durable=true
rabbitmqadmin declare binding source=my_dlx destination=my_dlq routing_key=dlx_routing_key

3. 设置原始队列的参数，包括死信交换机和死信路由键：

rabbitmqadmin declare queue name=my_queue durable=true arguments='{"x-dead-letter-exchange":"my_dlx", "x-dead-letter-routing-key":"dlx_routing_key"}'

4. 编写消费者代码，在消费者代码中拒绝投递消息到死信交换机：

//Consumer.ts
import * as amqp from 'amqplib';

async function main() {
    const connection = await amqp.connect('amqp://mingcai:password@127.0.0.1');
    const channel = await connection.createChannel();
    const queue = 'my_queue';
    await channel.consume(queue, async (msg) => {
        if (msg !== null) {
            try {
                await new Promise(resolve => {
                    setTimeout(()=>{
                        resolve(true)
                    },3000)
                })

                // Process the message
                console.log("Received message:", msg.content.toString());
                // Simulate rejection of message delivery to dead letter exchange
                throw new Error("Failed to process message, rejecting delivery to dead letter exchange");
            } catch (error) {
                // Reject the message delivery to dead letter exchange
                channel.reject(msg, false);
                console.error("Error processing message:", error.message);
            }
        }
    });

    console.log('Waiting for messages...');
}

main().catch(console.error);

在这个示例中，当消费者处理消息时发生错误时，它会将消息的投递拒绝到死信交换机。这样，这些被拒绝的消息将被重新路由到死信队列 my_dlq 中。

记得根据你的具体需求修改队列、交换机和消费者的配置，确保它们符合你的预期行为。

rabbitmqadmin purge queue name=my_dlq #删除队列中的所有消息

//Producer.ts 
import * as amqp from 'amqplib';


async function sendMsg() {
    try {
    const connection = await amqp.connect('amqp://mingcai:password@127.0.0.1');
        const channel = await connection.createChannel(); // 创建通道
        const delayQueue = 'my_queue'; // 延迟队列名称
    // 每秒发送一条消息
    for (let i = 0; i < 100; i++) {
        await new Promise(resolve => {
            setTimeout(() => {
                resolve(true)
            }, 1000)
        })
        const message = 'Hello RabbitMQ!';
        channel.sendToQueue(delayQueue, Buffer.from(message));
        console.log('消息已发送:', message);
    }
    } catch (error) {
        console.error('错误:', error);
    }
}

sendMsg()