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Sentinel初始化启动流程详细介绍

2023-05-20 10:26:15 作者：小白的救赎

Sentinel是一个分布式系统的流量控制组件，它可以实现限流与流控及降级等功能，提高系统的稳定性和可靠性，这篇文章主要介绍了Sentinel的初始化流程，感兴趣想要详细了解可以参考下文

概念

分布式系统的流量防卫兵。随着微服务的流行，服务和服务之间的稳定性变得越来越重要。Sentinel以流量为切入点，从流量控制、流量路由、熔断降级、系统自适应过载保护、热点流量防护等多个维度保护服务的稳定性。

特征

丰富的应用场景：Sentinel 承接了阿里巴巴近 10 年的双十一大促流量的核心场景，例如秒杀（即突发流量控制在系统容量可以承受的范围）、消息削峰填谷、集群流量控制、实时熔断下游不可用应用等。
完备的实时监控：Sentinel 同时提供实时的监控功能。您可以在控制台中看到接入应用的单台机器秒级数据，甚至 500 台以下规模的集群的汇总运行情况。
广泛的开源生态：Sentinel 提供开箱即用的与其它开源框架/库的整合模块，例如与 Spring Cloud、Apache Dubbo、gRPC、Quarkus 的整合。您只需要引入相应的依赖并进行简单的配置即可快速地接入 Sentinel。同时 Sentinel 提供 Java/Go/C++ 等多语言的原生实现。
完善的 SPI 扩展机制：Sentinel 提供简单易用、完善的 SPI 扩展接口。您可以通过实现扩展接口来快速地定制逻辑。例如定制规则管理、适配动态数据源等。

主要特征

开源生态

开启控制台

①在nacos-server/bin下双击startup.cmd

②在sentinel-dashboard下使用cmd输入：java -java sentinel-dashboard-1.6.3.jar

依据自己下载的版本而输入后面的jar包名称

在网页上输入localhost:8080/ 即可进入以下页面账号密码皆为sentinel

初始化工程

①构建模块导入依赖

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    <version>2.2.3.RELEASE</version>
</dependency>
<!--SpringCloud Alibaba Sentinel-datasource-nacos 持久化技术-->
<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-datasource-nacos</artifactId>
    <version>1.8.1</version>
</dependency>
<!--SpringCloud Alibaba Sentinel-->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
    <version>2.2.7.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
    <version>3.1.1</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

这里需要注意的是：如果自己的SpringBoot版本过低的话会报以下错误，我的Boot版本是2.2.6.RELEASE。

当然，如果SpringBoot版本过高会报以下错误：

2022-12-25 18:19:02.585 ERROR 7000 --- [ main] o.s.boot.SpringApplication : Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'configurationPropertiesBeans' defined in class path resource [org/springframework/cloud/autoconfigure/ConfigurationPropertiesRebinderAutoConfiguration.class]: Post-processing of merged bean definition failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [org.springframework.cloud.context.properties.ConfigurationPropertiesBeans] from ClassLoader [sun.misc.Launcher$AppClassLoader@18b4aac2]
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:597) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:213) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.context.support.PostProcessorRegistrationDelegate.registerBeanPostProcessors(PostProcessorRegistrationDelegate.java:270) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:762) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:567) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:740) [spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:415) [spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:164) ~[spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.cloud.bootstrap.BootstrapApplicationListener.bootstrapServiceContext(BootstrapApplicationListener.java:212) ~[spring-cloud-context-2.2.5.RELEASE.jar:2.2.5.RELEASE]
   at org.springframework.cloud.bootstrap.BootstrapApplicationListener.onApplicationEvent(BootstrapApplicationListener.java:117) ~[spring-cloud-context-2.2.5.RELEASE.jar:2.2.5.RELEASE]
   at org.springframework.cloud.bootstrap.BootstrapApplicationListener.onApplicationEvent(BootstrapApplicationListener.java:74) ~[spring-cloud-context-2.2.5.RELEASE.jar:2.2.5.RELEASE]
   at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:131) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:85) ~[spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$2(SpringApplicationRunListeners.java:66) ~[spring-boot-2.6.7.jar:2.6.7]
   at java.util.ArrayList.forEach(ArrayList.java:1257) ~[na:1.8.0_201]
   at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:120) ~[spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:114) ~[spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:65) ~[spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:339) [spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplication.run(SpringApplication.java:297) [spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplication.run(SpringApplication.java:1312) [spring-boot-2.6.7.jar:2.6.7]
   at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301) [spring-boot-2.6.7.jar:2.6.7]
   at com.chf.CloudalibabaSentinalService8401.main(CloudalibabaSentinalService8401.java:11) [classes/:na]
Caused by: java.lang.IllegalStateException: Failed to introspect Class [org.springframework.cloud.context.properties.ConfigurationPropertiesBeans] from ClassLoader [sun.misc.Launcher$AppClassLoader@18b4aac2]
   at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:485) ~[spring-core-5.3.19.jar:5.3.19]
   at org.springframework.util.ReflectionUtils.doWithLocalMethods(ReflectionUtils.java:321) ~[spring-core-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.buildLifecycleMetadata(InitDestroyAnnotationBeanPostProcessor.java:232) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.findLifecycleMetadata(InitDestroyAnnotationBeanPostProcessor.java:210) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(InitDestroyAnnotationBeanPostProcessor.java:149) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(CommonAnnotationBeanPostProcessor.java:305) ~[spring-context-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyMergedBeanDefinitionPostProcessors(AbstractAutowireCapableBeanFactory.java:1116) ~[spring-beans-5.3.19.jar:5.3.19]
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594) ~[spring-beans-5.3.19.jar:5.3.19]
   ... 30 common frames omitted
Caused by: java.lang.NoClassDefFoundError: org/springframework/boot/context/properties/ConfigurationBeanFactoryMetadata
   at java.lang.Class.getDeclaredMethods0(Native Method) ~[na:1.8.0_201]
   at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) ~[na:1.8.0_201]
   at java.lang.Class.getDeclaredMethods(Class.java:1975) ~[na:1.8.0_201]
   at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:467) ~[spring-core-5.3.19.jar:5.3.19]
   ... 37 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.context.properties.ConfigurationBeanFactoryMetadata
   at java.net.URLClassLoader.findClass(URLClassLoader.java:382) ~[na:1.8.0_201]
   at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_201]
   at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349) ~[na:1.8.0_201]
   at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_201]
   ... 41 common frames omitted

这两点都是我在学习时遇到的问题，希望看到对于这篇文章的人能有所帮助。

②改application.yml

server:
port: 8401
spring:
application:
name: cloud-sentinel-service
cloud:
nacos:
discovery:
server-addr: localhost:8848 #Nacos服务注册中心地址
sentinel:
transport:
dashboard: localhost:8080 #配置 dashboard监控平台地址
port: 8719 #默认8719端口如果被占用就自增直至找到未被占用的端口
management:
endpoint:
sentinel:
enabled: true
endpoints:
web:
exposure:
include: '*'

③改启动类只需在上面加个注解@EnableDiscoveryClient

@SpringBootApplication
@EnableDiscoveryClient //表明让注册中心清楚当前服务想被注册进去
public class CloudalibabaSentinalService {
    public static void main(String[] args) {
        SpringApplication.run(CloudalibabaSentinalService.class, args);
    }
}

④写控制层

@RestController
public class SentinelController {
    @Value("${server.port}")
    private String serverPort;
    @GetMapping("/test")
    public String test(){
        return "Sentinel test server_port：" + serverPort;
    }
}

⑤测试。即启动当前类。由于Sentinel是懒加载机制，所以需要先测试我们的控制层，这样页面才能显示到我们的服务。可以多运行几次这个方法即多刷新这个页面

到此这篇关于Sentinel初始化启动流程详细介绍的文章就介绍到这了,更多相关Sentinel初始化内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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