Spring Cloud（十五）Spring Cloud Bus实战

水深无声 2022-11-20 12:58 233阅读 0赞

Spring Cloud Bus可以将分布式系统的节点与轻量级消息代理链接，然后可以实现广播状态更改（例如配置更改）或广播其他管理指令。Spring Cloud Bus就像一个分布式执行器，用于扩展的Spring Boot应用程序，但也可以用作应用程序之间的通信通道。那么这里就涉及到了消息代理，目前流行的消息代理中间件有不少，Spring Cloud Bus支持RabbitMQ和Kafka

## 1、Spring Cloud Bus实现通知微服务的配置文件的更改 ##

参考[Spring Cloud（十四）Config实战][Spring Cloud_Config]

修改config-client

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.yi</groupId>
        <artifactId>config-client</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <name>config-client</name>
        <description>config-client</description>
    
        <parent>
            <groupId>com.yi</groupId>
            <artifactId>config</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-config</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-bus-amqp</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    </project>

application.yml

spring:
      cloud:
        bus:
          enabled: true
          trace:
            enabled: true
      rabbitmq:
        host: localhost
        port: 5672
        username: guest
        password: guest
    
    
    management:
      endpoints:
        web:
          exposure:
            include: bus-refresh

> 增加RabbitMq配置，和spring cloud bus支持

package com.yi.configclient;
    
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.context.config.annotation.RefreshScope;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @SpringBootApplication
    @EnableEurekaClient
    @EnableDiscoveryClient
    @RestController
    @RefreshScope
    public class ConfigClientApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(ConfigClientApplication.class, args);
        }
    
        @Value("${version}")
        String version;
    
        @RequestMapping(value = "/helloWorld")
        public String helloWorld() {
            return "版本号："+version;
        }
    }

安装并启动RabbitMq，参考 [RabbitMQ自学之路（二）——windows下安装RabbitMQ和Erlang][RabbitMQ_windows_RabbitMQ_Erlang]

修改 git上配置文件，`version = 3`，改变配置文件值。

在没有使用spring cloud bus前，需要重新启动服务，才会生效。

使用后，发送post请求：`http://localhost:8881/actuator/bus-refresh` ，重新读取配置文件

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5OTE0ODM3_size_16_color_FFFFFF_t_70_pic_center]

访问`http://localhost:8881/helloWorld`

![在这里插入图片描述][20201028225108464.png_pic_center]

当git上配置文件变更的时候，发送post请求向config-client，接收到后由消息总线向其它服务传递，从而整改微服务集群全部配置文件更新

> spring cloud config配置文件更新有两种。  
> 1、是自动更新，配置git仓库的web hook，当git仓库有更新时自动调用bus提供的刷新接口，刷新缓存  
> 2、手动调用bus提供的刷新接口  
> PS：实际工作多是采用第二种，保障配置文件修改无误，防止误操作

--------------------

git项目源码：[https://github.com/yilei111/-Spring-Cloud-Finchley][https_github.com_yilei111_-Spring-Cloud-Finchley]

[Spring Cloud_Config]: https://blog.csdn.net/qq_29914837/article/details/109301137
[RabbitMQ_windows_RabbitMQ_Erlang]: https://blog.csdn.net/qq_29914837/article/details/92437791
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5OTE0ODM3_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/9ef02b2797b9440c987145ae82d7430d.png
[20201028225108464.png_pic_center]: https://img-blog.csdnimg.cn/20201028225108464.png#pic_center
[https_github.com_yilei111_-Spring-Cloud-Finchley]: https://github.com/yilei111/-Spring-Cloud-Finchley