RabbitMQ - 快速入门（二）

使用stream发送和接收消息

1. 引入依赖 spring-cloud-starter-stream-rabbit

2. 配置 rabbitMq

3. 新建接口 StreamClient，分别定义 input() 和 output()

4. 接收端

5. 发送端

• SpringCloud Stream 提供更方便的消息处理，达到代码层面对消息中间件的无感知的效果，支持 RabbitMQ 和 Kafka。只需定义 Input 和 Output，无需过多考虑 Rabbitmq 的 Exchange 和 RoutingKey。

Order

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-amqp</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-stream-rabbit</artifactId>
</dependency>

package com.imooc.order.message;

import org.springframework.cloud.stream.annotation.Input;
import org.springframework.cloud.stream.annotation.Output;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.SubscribableChannel;

public interface StreamClient {

    String INPUT = "myMessage";

    String INPUT2 = "myMessage2";

    @Input(StreamClient.INPUT)
    SubscribableChannel input();

    @Output(StreamClient.INPUT)
    MessageChannel output();

    @Input(StreamClient.INPUT2)
    SubscribableChannel input2();

    @Output(StreamClient.INPUT2)
    MessageChannel output2();
}

package com.imooc.order.controller;

import com.imooc.order.dto.OrderDTO;
import com.imooc.order.message.StreamClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.Date;

@RestController
public class SendMessageController {

    @Autowired
    private StreamClient streamClient;

//    @GetMapping("/sendMessage")
//    public void process() {
//        String message = "now " + new Date();
//        streamClient.output().send(MessageBuilder.withPayload(message).build());
//    }

    /**
     * 发送 orderDTO对象
     */
    @GetMapping("/sendMessage")
    public void process() {
        OrderDTO orderDTO = new OrderDTO();
        orderDTO.setOrderId("123456");
        streamClient.output().send(MessageBuilder.withPayload(orderDTO).build());
    }
}

package com.imooc.order.message;

import com.imooc.order.dto.OrderDTO;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.annotation.StreamListener;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.stereotype.Component;

@Component
@EnableBinding(StreamClient.class)
@Slf4j
public class StreamReceiver {

//    @StreamListener(value = StreamClient.INPUT)
//    public void process(Object message) {
//        log.info("StreamReceiver: {}", message);
//    }

    /**
     * 接收orderDTO对象 消息
     * @param message
     */
    @StreamListener(value = StreamClient.INPUT)
    @SendTo(StreamClient.INPUT2) // 接收消息后，回复消息，或间接转发消息
    public String process(OrderDTO message) {
        log.info("StreamReceiver: {}", message);
        return "received.";
    }

    @StreamListener(value = StreamClient.INPUT2)
    public void process2(String message) {
        log.info("StreamReceiver2: {}", message);
    }
}

• @SendTo(StreamClient.INPUT2)：接收消息后，回复消息，或间接转发消息。

启动多个同服务时会有多个实例，如何做到只让一个实例收到消息？

stream有个分组，配置下就好：

spring:
  cloud:
    stream:
      bindings:
        myMessage:
          group: order
          content-type: application/json

•  支持复杂对象消息，需要配置参数套路： content-type: application/json，效果图对比使用前后，如下图。

• 使用前

• 使用后