Bus Message Bus :
Well, now we went on an essay, continued speaking. Previous we talked about, if we're going to update the configuration of all micro services, continue to update configuration without rebooting, can only rely on a spring cloud config, however, it is that we want to send a post request a service of a service,
We can be affected by it? This center is not configured than the previous much better, how do we continue to avoid one by one by sending a request to inform the Post Service to the service, you change the configuration information, the need for timely modify the configuration information in memory.
At this time we do not forget the publish-subscribe model of message queues. All for the service to subscribe to this event, when the event is changed, and you can notify all micro services to update their configuration information in memory.
Then Bus message bus can be solved, you only need to issue refresh in springcloud Config Server side, you can trigger all the micro-updating service.
Spring Cloud Bus In addition to support automated configuration of RabbitMQ, but also supports Kafka is now widely used. In this article, we will build a Kafka local environment, and through it to try to use the Spring Cloud Bus support for Kafka, realize the message bus functions.
Installation kafka and zooker next window, ultra-detailed: https://blog.csdn.net/weixin_33446857/article/details/81982455
kafka: Installation Tutorial Download URL (CentOS Linux): https://www.cnblogs.com/subendong/p/7786547.html
zooker download and install URL: https://blog.csdn.net/ring300/article/details/80446918
Project: a server. 2 clients.
pom file:
<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.demo</groupId>
<artifactId>springcloud_serviceClient2</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.3.RELEASE</version>
<relativePath/>
</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>Finchley.RELEASE</spring-cloud.version>
</properties>
<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>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka-server</artifactId>
<version>1.3.4.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-bus-kafka</artifactId>
<version>1.3.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
<version>1.4.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-config-client</artifactId>
<version>1.4.0.RELEASE</version>
</dependency>
<!--Spring Boot Actuator，感应服务端变化-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
client1 configuration file should be changed to bootstrap.yml, because this configuration format, is a priority loaded on an essay have talked about, client2 configuration is as follows:
server:
port: 7008
spring:
application:
name: config2
cloud:
config:
label: master
#启动什么环境下的配置，dev 表示开发环境，这跟你仓库的文件的后缀有关，比如，仓库配置文件命名格式是cloud-config-dev.properties,所以profile 就要写dev
profile: dev
name: cloud-config
discovery:
enabled: true
#这个名字是Config Server端的服务名字，不能瞎写。
service-id: CONFIG-SERVER
management:
#是否需要权限拉去，默认是true,如果不false就不允许你去拉取配置中心Server更新的内容
security:
enabled: false
#注册中心
eureka:
client:
service-url:
defaultZone: http://localhost:8001/eureka/
启动类：
package cn.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient
public class ClientApplication2 {
public static void main(String[] args) {
SpringApplication.run(ClientApplication2.class, args);
System.out.println("启动成功!");
controller类：
package cn.demo.web;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RefreshScope
public class Controller {
/*@Value("${spring.cloud}")
private String config;
@GetMapping("/test/config")
public String test() {
return config;
}*/
@Value("${name}")
private String name;
@Value("${age}")
private Integer age;
@RequestMapping("/test")
public String test(){
return this.name+this.age;
}
}
接着将client2中的的代码基本和client的一样，只是暴露服务的端口不同。
然后：
把zooker，kafka启动；（标题下面链接）
把前面的工程，1个注册中心，一个springcloud-config-server,两个springcloud-config-client,springcloud-config-client1启动起来，
可以看到springcloudBus是在0分片上，如果两个config-client启动都出现上面信息，证明启动成功了。
访问：http://localhost:7000/cloud-config-dev.properties
再访问两个client,如下：
http://localhost:7006/test http://localhost:7008/test
好了，好戏开始了，现在我们去git仓库上修改配置中心的文件，将年龄改为24，如下：
接下来，我们我们用refresh刷新配置服务端7000配置，通知两个client去更新内存中的配置信息。用postman发送localhost:7000/bus/refresh,如下：
注意：spring1.x和spring2.x 刷新的路径不一样。
----------------------------------------------------
看一下返回的结果：
可以看到没有返回什么信息，但是不要担心，这是成功的通知所有client去更新了内存中的信息了。
接着我们分别重新请求config-server,两个client,刷新页面，结果如下：
到目前为止，上面都是刷新说有的配置的信息的，如果我们想刷新某个特定服务的配置信息也是可以的。我们可以指定刷新范围，如下：
指定刷新范围
上面的例子中，我们通过向服务实例请求Spring Cloud Bus的/bus/refresh接口，从而触发总线上其他服务实例的/refresh。但是有些特殊场景下（比如：灰度发布），我们希望可以刷新微服务中某个具体实例的配置。
Spring Cloud Bus对这种场景也有很好的支持：/bus/refresh接口还提供了destination参数，用来定位具体要刷新的应用程序。比如，我们可以请求/bus/refresh?destination=服务名字:9000，此时总线上的各应用实例会根据destination属性的值来判断是否为自己的实例名，
若符合才进行配置刷新，若不符合就忽略该消息。
destination参数除了可以定位具体的实例之外，还可以用来定位具体的服务。定位服务的原理是通过使用Spring的PathMatecher（路径匹配）来实现，比如：/bus/refresh?destination=customers:**，该请求会触发customers服务的所有实例进行刷新。