Publish模式
2021.07

Publish模式(订阅模式,消息被路由投递给多个队列,一个消息被多个消费者获取)

Publish模式

X代表交换机rabbitMQ内部组件,erlang 消息产生者是代码完成,代码的执行效率不高,消息产生者将消息放入交换机,交换机发布订阅把消息发送到所有消息队列中,对应消息队列的消费者拿到消息进行消费相关场景:邮件群发,群聊天,广播(广告) 目录结构 Publish模式 kuteng-RabbitMQ -RabbitMQ –rabitmq.go //这个是RabbitMQ的封装 -Pub –mainPub.go //Publish 先启动 -Sub –mainSub.go -Sub2 –mainSub.go rabitmq.go代码

package RabbitMQ

import (
    "fmt"
    "log"

    "github.com/streadway/amqp"
)

//连接信息
const MQURL = "amqp://kuteng:kuteng@127.0.0.1:5672/kuteng"

//rabbitMQ结构体
type RabbitMQ struct {
    conn    *amqp.Connection
    channel *amqp.Channel
    //队列名称
    QueueName string
    //交换机名称
    Exchange string
    //bind Key 名称
    Key string
    //连接信息
    Mqurl string
}

//创建结构体实例
func NewRabbitMQ(queueName string, exchange string, key string) *RabbitMQ {
    return &RabbitMQ{QueueName: queueName, Exchange: exchange, Key: key, Mqurl: MQURL}
}

//断开channel 和 connection
func (r *RabbitMQ) Destory() {
    r.channel.Close()
    r.conn.Close()
}

//错误处理函数
func (r *RabbitMQ) failOnErr(err error, message string) {
    if err != nil {
        log.Fatalf("%s:%s", message, err)
        panic(fmt.Sprintf("%s:%s", message, err))
    }
}

//订阅模式创建RabbitMQ实例
func NewRabbitMQPubSub(exchangeName string) *RabbitMQ {
    //创建RabbitMQ实例
    rabbitmq := NewRabbitMQ("", exchangeName, "")
    var err error
    //获取connection
    rabbitmq.conn, err = amqp.Dial(rabbitmq.Mqurl)
    rabbitmq.failOnErr(err, "failed to connect rabbitmq!")
    //获取channel
    rabbitmq.channel, err = rabbitmq.conn.Channel()
    rabbitmq.failOnErr(err, "failed to open a channel")
    return rabbitmq
}

//订阅模式生产
func (r *RabbitMQ) PublishPub(message string) {
    //1.尝试创建交换机
    err := r.channel.ExchangeDeclare(
        r.Exchange,
        "fanout",
        true,
        false,
        //true表示这个exchange不可以被client用来推送消息,仅用来进行exchange和exchange之间的绑定
        false,
        false,
        nil,
    )

    r.failOnErr(err, "Failed to declare an excha"+
        "nge")

    //2.发送消息
    err = r.channel.Publish(
        r.Exchange,
        "",
        false,
        false,
        amqp.Publishing{
            ContentType: "text/plain",
            Body:        []byte(message),
        })
}

//订阅模式消费端代码
func (r *RabbitMQ) RecieveSub() {
    //1.试探性创建交换机
    err := r.channel.ExchangeDeclare(
        r.Exchange,
        //交换机类型
        "fanout",
        true,
        false,
        //YES表示这个exchange不可以被client用来推送消息,仅用来进行exchange和exchange之间的绑定
        false,
        false,
        nil,
    )
    r.failOnErr(err, "Failed to declare an exch"+
        "ange")
    //2.试探性创建队列,这里注意队列名称不要写
    q, err := r.channel.QueueDeclare(
        "", //随机生产队列名称
        false,
        false,
        true,
        false,
        nil,
    )
    r.failOnErr(err, "Failed to declare a queue")

    //绑定队列到 exchange 中
    err = r.channel.QueueBind(
        q.Name,
        //在pub/sub模式下,这里的key要为空
        "",
        r.Exchange,
        false,
        nil)

    //消费消息
    messges, err := r.channel.Consume(
        q.Name,
        "",
        true,
        false,
        false,
        false,
        nil,
    )

    forever := make(chan bool)

    go func() {
        for d := range messges {
            log.Printf("Received a message: %s", d.Body)
        }
    }()
    fmt.Println("退出请按 CTRL+C\n")
    <-forever
}

mainPub.go代码

package main

import (
    "fmt"
    "strconv"
    "time"

    "github.com/student/kuteng-RabbitMQ/RabbitMQ"
)

func main() {
    rabbitmq := RabbitMQ.NewRabbitMQPubSub("" +
        "newProduct")
    for i := 0; i < 100; i++ {
        rabbitmq.PublishPub("订阅模式生产第" +
            strconv.Itoa(i) + "条" + "数据")
        fmt.Println("订阅模式生产第" +
            strconv.Itoa(i) + "条" + "数据")
        time.Sleep(1 * time.Second)
    }

}

mainSub.go代码(两个消费者代码是一样的)

package main

import "github.com/student/kuteng-RabbitMQ/RabbitMQ"

func main() {
    rabbitmq := RabbitMQ.NewRabbitMQPubSub("" +
        "newProduct")
    rabbitmq.RecieveSub()
}
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