Spring Cloud Stream

Spring Cloud Stream 在 Spring Cloud 体系内用于构建高度可扩展的基于事件驱动的微服务，其目的是为了简化消息在 Spring Cloud 应用程序中的开发。

是一款用于构建消息驱动的微服务应用程序的轻量级框架 

应用程序通过 inputs 或者 outputs 来与 Spring Cloud Stream 中binder 交互

Spring Cloud Stream 的 binder 负责与消息中间件交互 

Binder

RabbitMQ

Apache Kafka

Kafka Streams

Amazon Kinesis

RocketMQ 

通过Spring Cloud Stream访问 RabbitMQ

1.RabbitMQ

RabbitMQ is the most widely deployed open source message broker

RabbitMQ是一个基于AMQP协议的高级消息中间件，它主要的技术特点是可用性，安全性，集群，多协议支持，可视化的客户端，活跃的社区

2.docker安装rabbitmq

使用的是带 web 管理插件的镜像

docker pull rabbitmq:management

运行

docker run --name rabbitmq -d -p 5672:5672 -p 15672:15672  -e RABBITMQ_DEFAULT_USER=spring -e RABBITMQ_DEFAULT_PASS=spring rabbitmq:management

5672 应用访问端口

15672 控制台Web端口号

访问管理端了 http://宿主机IP:15672

eg:

http://192.168.99.100:15672/

说明：

　　默认创建了一个 guest 用户，密码也是 guest

　　这里在启动的时候指定了用户名spring密码spring

在线的RabbitMQ模拟器 http://tryrabbitmq.com

3.示例

（1）service-provider

添加依赖

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

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

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

配置

server.port=8010
management.endpoints.web.exposure.include=*
management.endpoint.health.show-details=always
spring.application.name=service-provider
spring.cloud.consul.host=192.168.99.100
spring.cloud.consul.port=8500
spring.cloud.consul.discovery.health-check-path=/actuator/health
spring.cloud.consul.discovery.service-name=${spring.application.name}
spring.cloud.consul.discovery.heartbeat.enabled=true
spring.cloud.consul.discovery.prefer-ip-address=true

spring.rabbitmq.host=192.168.99.100
spring.rabbitmq.port=5672
spring.rabbitmq.username=spring
spring.rabbitmq.password=spring

spring.cloud.stream.bindings.finishedOrders.group=service-provider

 启动类

@EnableBinding注解，传入Barista告诉Spring加载

package com.xyz.provider;

import com.xyz.provider.integration.Barista;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.stream.annotation.EnableBinding;

@EnableDiscoveryClient
@SpringBootApplication
@EnableBinding(Barista.class)
public class ProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(ProviderApplication.class, args);
    }

}

使用SubscribableChannel和@Input注解连接到newOrders，消息数据将被推送这里

监听通道创建一个绑定

package com.xyz.provider.integration;
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 Barista {
    String NEW_ORDERS = "newOrders";
    String FINISHED_ORDERS = "finishedOrders";

    @Input
    SubscribableChannel finishedOrders();

    @Output
    MessageChannel newOrders();
}

消费消息的类

package com.xyz.provider.integration;

import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.stream.annotation.StreamListener;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class OrderListener {
    @StreamListener(Barista.FINISHED_ORDERS)
    public void listenFinishedOrders(Integer num) {
        log.info("We've finished an order [{}].", num);
    }
}

控制器

package com.xyz.provider.controller;

import com.xyz.provider.service.OrderService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@Slf4j
public class demoController {

    @Autowired
    private OrderService orderService;

    @RequestMapping("/rabbitmq")
    public String rabbitmq(Integer num) {
        log.info("msq num: ", num);
        orderService.updateNum(num);
        return "ok";
    }
}

消费消息的类

package com.xyz.provider.service;

import com.xyz.provider.integration.Barista;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service
@Transactional
@Slf4j
public class OrderService{

    @Autowired
    private Barista barista;
    public boolean updateNum(Integer num) {
        num++;
        System.out.println(num);
        barista.newOrders().send(MessageBuilder.withPayload(num).build());
        return true;
    }
}

service-comsumer

依赖

<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
     <groupId>org.springframework.cloud</groupId>
     <artifactId>spring-cloud-starter-consul-discovery</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-stream-rabbit</artifactId>
</dependency>

配置

server.port=8015
spring.application.name=service-comsumer
management.endpoints.web.exposure.include=*
management.endpoint.health.show-details=always
spring.cloud.consul.host=192.168.99.100
spring.cloud.consul.port=8500
spring.cloud.consul.discovery.health-check-path=/actuator/health
spring.cloud.consul.discovery.service-name=${spring.application.name}
spring.cloud.consul.discovery.heartbeat.enabled=true
spring.rabbitmq.host=192.168.99.100
spring.rabbitmq.port=5672
spring.rabbitmq.username=spring
spring.rabbitmq.password=spring
spring.cloud.stream.bindings.newOrders.group=service-comsumer

启动类

@EnableBinding注解，传入Waiter告诉Spring加载

package com.xyz.comsumer;

import com.xyz.comsumer.integration.Waiter;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.cloud.stream.annotation.EnableBinding;

@EnableFeignClients
@SpringBootApplication
@EnableBinding(Waiter.class)
public class ComsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(ComsumerApplication.class, args);
    }


}

消费消息的类

使用MessageBuilder创建一个String类型的消息

使用MessageChannel上的.send()方法来发布消息

package com.xyz.comsumer.integration;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.cloud.stream.annotation.StreamListener;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

@Component
@Slf4j
@Transactional
public class OrderListener {
    @Autowired
    @Qualifier(Waiter.FINISHED_ORDERS)
    private MessageChannel finishedOrdersMessageChannel;
    @StreamListener(Waiter.NEW_ORDERS)
    public void processNewOrder(Integer num) {
        num++;
        log.info("Receive a new order",
                num);
        System.out.println(num);
        finishedOrdersMessageChannel.send(MessageBuilder.withPayload(num).build());
    }
}

监听通道创建一个绑定

package com.xyz.comsumer.integration;

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 Waiter {
    String NEW_ORDERS = "newOrders";
    String FINISHED_ORDERS = "finishedOrders";

    @Input(NEW_ORDERS)
    SubscribableChannel newOrders();

    @Output(FINISHED_ORDERS)
    MessageChannel finishedOrders();
}

启动rabbitmq

启动consul

启动service-provider

启动service-comsumer

GET  http://172.27.0.17:8010/rabbitmq?num=1

返回OK

控制台消息也输出了

 说明：

　　如果出现

ERROR 13220 --- [ main] o.s.boot.SpringApplication : Application run failed

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to process import candidates for configuration class [com.xyz.provider.ProviderApplication]; nested exception is java.lang.IllegalStateException: Failed to introspect annotated methods on class org.springframework.cloud.stream.config.BinderFactoryConfiguration
　　可以换下

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.4.RELEASE</version>
    <relativePath/>
</parent>

　　及

<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
</dependencyManagement>