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Sentinel初始化啟動流程詳細(xì)介紹

更新時間：2023年05月20日 10:30:18 作者：小白的救贖

Sentinel是一個分布式系統(tǒng)的流量控制組件，它可以實(shí)現(xiàn)限流與流控及降級等功能，提高系統(tǒng)的穩(wěn)定性和可靠性，這篇文章主要介紹了Sentinel的初始化流程，感興趣想要詳細(xì)了解可以參考下文

概念

分布式系統(tǒng)的流量防衛(wèi)兵。隨著微服務(wù)的流行，服務(wù)和服務(wù)之間的穩(wěn)定性變得越來越重要。Sentinel以流量為切入點(diǎn)，從流量控制、流量路由、熔斷降級、系統(tǒng)自適應(yīng)過載保護(hù)、熱點(diǎn)流量防護(hù)等多個維度保護(hù)服務(wù)的穩(wěn)定性。

特征

豐富的應(yīng)用場景：Sentinel 承接了阿里巴巴近 10 年的雙十一大促流量的核心場景，例如秒殺（即突發(fā)流量控制在系統(tǒng)容量可以承受的范圍）、消息削峰填谷、集群流量控制、實(shí)時熔斷下游不可用應(yīng)用等。
完備的實(shí)時監(jiān)控：Sentinel 同時提供實(shí)時的監(jiān)控功能。您可以在控制臺中看到接入應(yīng)用的單臺機(jī)器秒級數(shù)據(jù)，甚至 500 臺以下規(guī)模的集群的匯總運(yùn)行情況。
廣泛的開源生態(tài)：Sentinel 提供開箱即用的與其它開源框架/庫的整合模塊，例如與 Spring Cloud、Apache Dubbo、gRPC、Quarkus 的整合。您只需要引入相應(yīng)的依賴并進(jìn)行簡單的配置即可快速地接入 Sentinel。同時 Sentinel 提供 Java/Go/C++ 等多語言的原生實(shí)現(xiàn)。
完善的 SPI 擴(kuò)展機(jī)制：Sentinel 提供簡單易用、完善的 SPI 擴(kuò)展接口。您可以通過實(shí)現(xiàn)擴(kuò)展接口來快速地定制邏輯。例如定制規(guī)則管理、適配動態(tài)數(shù)據(jù)源等。

主要特征

開源生態(tài)

開啟控制臺

①在nacos-server/bin下雙擊startup.cmd

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

依據(jù)自己下載的版本而輸入后面的jar包名稱

在網(wǎng)頁上輸入localhost:8080/ 即可進(jìn)入以下頁面賬號密碼皆為sentinel

初始化工程

①構(gòu)建模塊導(dǎo)入依賴

<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 持久化技術(shù)-->
<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>

這里需要注意的是：如果自己的SpringBoot版本過低的話會報以下錯誤，我的Boot版本是2.2.6.RELEASE。

當(dāng)然，如果SpringBoot版本過高會報以下錯誤：

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

這兩點(diǎn)都是我在學(xué)習(xí)時遇到的問題，希望看到對于這篇文章的人能有所幫助。

②改application.yml

server:
port: 8401
spring:
application:
name: cloud-sentinel-service
cloud:
nacos:
discovery:
server-addr: localhost:8848 #Nacos服務(wù)注冊中心地址
sentinel:
transport:
dashboard: localhost:8080 #配置 dashboard監(jiān)控平臺地址
port: 8719 #默認(rèn)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改啟動類只需在上面加個注解@EnableDiscoveryClient

@SpringBootApplication
@EnableDiscoveryClient //表明讓注冊中心清楚當(dāng)前服務(wù)想被注冊進(jìn)去
public class CloudalibabaSentinalService {
    public static void main(String[] args) {
        SpringApplication.run(CloudalibabaSentinalService.class, args);
    }
}

④寫控制層

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

⑤測試。即啟動當(dāng)前類。由于Sentinel是懶加載機(jī)制，所以需要先測試我們的控制層，這樣頁面才能顯示到我們的服務(wù)?？梢远噙\(yùn)行幾次這個方法即多刷新這個頁面