消息总线

SpringCloudBus：事件、消息总线，用于在集群（例如，配置变化事件）中传播状态变化，可与Spring Cloud Config联合实现热部署。

在上一篇写出了springcloud对微服务的集中配置，那么就出现了一个问题，如果修改配置了怎么实现不需重启服务来实现配置的更新，下面有集中解决方法。

1.使用/refresh手动刷新配置

缺点：单点刷新，如果集群服务多的话，无论是工作量还是维护上都十分麻烦。

使用上一篇的config-client服务，加入依赖，

spring-boot-starter-actuator

pom文件如下：

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.dalaoyang</groupId>
	<artifactId>springcloud_config_client</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>springcloud_config_client</name>
	<description>springcloud_config_client</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.9.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Edgware.SR1</spring-cloud.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka</artifactId>
		</dependency>

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

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

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

	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>${spring-cloud.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>


</project>

在Controller类上加入@RefreshScope注解，由于上一篇controller写在了启动类上，所以直接加在启动类上，代码如下：

package com.dalaoyang;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController
@RefreshScope
public class SpringcloudConfigClientApplication {

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


	@Value("${title}")
	String title;

	@RequestMapping("/getTitle")
	public String getTitle(){
		return title;
	}

}

配置文件新增配置management.security.enabled=false，在刷新时关闭安全验证。

代码如下：

spring.application.name=config-client
spring.cloud.config.label=master
spring.cloud.config.profile=test
spring.cloud.config.uri= http://localhost:9000/

##注册中心地址
eureka.client.service-url.defaultZone=http://eureka.dalaoyang.cn/eureka/

## 刷新时，关闭安全验证
management.security.enabled=false

分别启动项目config-server，config-client。访问http://localhost:8080/getTitle，结果如下图

修改git上配置，修改为dalaoyang_test_change，在次请求，结果没有改变，使用postman或者其他工具post请求http://localhost:8080/getTitle看到返回如下结果。

在次访问http://localhost:8080/getTitle，如下图

2.使用springcloudbus刷新配置

springcloudbus需要使用轻量消息代理，本文使用rabbitmq，启动rabbitmq如下图：

访问http://localhost:15672/#/如下图

新建项目springcloud_bus，同时改造config-client，pom文件加入bus依赖，代码如下：

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.dalaoyang</groupId>
	<artifactId>springcloud_bus</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>springcloud_bus</name>
	<description>springcloud_bus</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.9.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Edgware.SR1</spring-cloud.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka</artifactId>
		</dependency>

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

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

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

		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-bus-amqp</artifactId>
		</dependency>
	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>${spring-cloud.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>


</project>

加入rabbitmq配置，配置文件如下：

spring.rabbitmq.host=localhost
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

##端口号
server.port=8881

## 刷新时，关闭安全验证
management.security.enabled=false

spring.application.name=config-client
spring.cloud.config.label=master
spring.cloud.config.profile=test
spring.cloud.config.uri= http://localhost:9000/

##注册中心地址
eureka.client.service-url.defaultZone=http://eureka.dalaoyang.cn/eureka/

启动类加入注解@RefreshScope，代码如下：

package com.dalaoyang;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController
@RefreshScope
public class SpringcloudBusApplication {

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


	@Value("${title}")
	String title;

	@RequestMapping("/getTitle")
	public String getTitle(){
		return title;
	}
}

config-client加入同样依赖和配置，重启config-client，启动springcloud_bus，先去http://eureka.dalaoyang.cn/，可以看到

先将git上配置改回dalaoyang_test，分别请求http://localhost:8881/getTitle和http://localhost:8080/getTitle结果如下：

然后用postman使用post请求访问http://localhost:8881/bus/refresh

再次分别请求http://localhost:8881/getTitle和http://localhost:8080/getTitle结果如下：

从图中可以看出刷新配置成功。

3.局部刷新配置，配置与第2种方法一样，只是在使用postman刷新时略加改变，在本文中使用http://localhost:8881/bus/refresh?destination=config-client:8881可以刷新服务名为config-client端口为8881的服务，如果想要刷新服务名为config-client的所有服务可以写成http://localhost:8881/bus/refresh?destination=config-client:**

源码下载 ：大老杨码云

个人网站：https://www.dalaoyang.cn