Spring Cloud实战(六)-Spring Cloud Netflix Bus

概要

• 什么是Spring Cloud Netflix Bus?
• 怎么用 Spring Cloud Netflix Bus?

什么是Spring Cloud Netflix Bus?

Spring Cloud Netflix Bus是Spring Cloud的消息机制,当Git Repository 改变时,通过POST请求Config Server的/bus/refresh,Config Server 会从repository获取最新的信息并通过amqp传递给client,如图所示.

Spring Cloud Bus的更新只对三种情况有效

1. @ConfigurationProperties
2. @RefreshScope
3. 日志级别

怎么用Spring Cloud Netflix Bus?

百说不如一run,构造一个例子来实现

• 基于实战一的例子
• 下载并运行rabbit
• 在Config Server及client添加bus,actuator依赖

         <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>

@ConfigurationProperties 实现

• 修改Config Client 的LuckyWordController,注意去掉@Value注解,和添加getter/setter

@RestController
@ConfigurationProperties(prefix = "wordConfig")
public class LuckyWordController {

    String luckyWord;

    @RequestMapping("/lucky-word")
    public String showLuckyWord() {
        return "The lucky word is: " + luckyWord;
    }

    public String getLuckyWord() {
        return luckyWord;
    }

    public void setLuckyWord(String luckyWord) {
        this.luckyWord = luckyWord;
    }
}

@RefreshScope 实现

@RestController
@RefreshScope
public class LuckyWordController {

    @Value("${wordConfig.luckyWord}")String luckyWord;
    
    @RequestMapping("/lucky-word")
    public String showLuckyWord() {
        return "The lucky word is: " + luckyWord;
    }
}

• 修改git repository

wordConfig:
  luckyWord: mmb

• 查看http://localhost:8002/lucky-word
• 修改git repository

wordConfig:
  luckyWord: mmb222

• POST请求http://localhost:8001/bus/ref...
• 查看http://localhost:8002/lucky-word 是否改变

@ConfigurationProperties的改变时直接重新绑定
@RefreshScope不仅仅是重新绑定,它是重新再绑定一个bean.@RefreshScope的工作原理Spring创建一个代理Proxy,Proxy中包含注入的依赖及调用目标bean的方法,当更新Refresh时,新Proxy就会指向改变的bean,而老的Proxy还指向老的bean.所以它更安全

特别感谢 kennyk65
Spring Cloud 中文用户组 31777218
Spring-Cloud-Config 官方文档-中文译本
Spring Cloud Netflix 官网文档-中文译本
本文实例github地址