一、Sentinel简介

1、官网

http://github.com/alibaba/Sentinel

中文文档：https://github.com/alibaba/Sentinel/wiki/%E4%BB%8B%E7%BB%8D

2、是什么？

一句话总结来说：升级版的Hystrix

3、下载地址

http://github.com/alibaba/Sentinel/releases

4、能干嘛

5、怎么玩

官网教你如何使用Sentinel

https://spring-cloud-alibaba-group.github.io/github-pages/greenwich/spring-cloud-alibaba.html#_spring_cloud_alibaba_sentinel

6、Sentinel和Hystrix的对比

二、安装Sentinel控制台

1、Sentinel分为两个部分

核心库（JAVA客户端）不依赖任何框架/库，能够运行于所有java运行时环境，同时对Dubbo,Spring Cloud框架也有较好的支持

控制台（Dashboard）基于SpringBoot开发打包后直接运行，不需要Tomcat等应用

2、安装

1）下载 Sentinel-dashboard

https://github.com/alibaba/Sentinel/releases

2）运行命令 ： java -jar sentinel-dashboard-1.7.0.jar

3）访问sentinel管理界面

localhost:8080

登录账号密码均为 sentinel

三、演示工程整合Sentinel

1、启动Nacos8848

2、新建module cloudalibaba-sentinel-service8401 整合Sentinel

1）新建module （maven工程）

2）添加pom文件

<dependencies>
        <dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <!--SpringCloud ailibaba nacos -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--SpringCloud ailibaba sentinel-datasource-nacos 后续做持久化用到-->
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-datasource-nacos</artifactId>
        </dependency>
        <!--SpringCloud ailibaba sentinel -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>
        <!--openfeign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!-- SpringBoot整合Web组件+actuator -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--日常通用jar包配置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>4.6.3</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

3）添加yml文件

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-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Sentinel dashboard地址
        #在应用对应的机器上启动一个 Http Server，该 Server 会与 Sentinel 控制台做交互
        port: 8719

management:
  endpoints:
    web:
      exposure:
        include: '*'

4）主启动类

@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }
}

5）controller

@RestController
public class TestController {

    @GetMapping("testA")
    public String getA(){
        return "test a";
    }

    @GetMapping("testB")
    public String getB(){
        return "test b";
    }
}

3、启动Sentinel8080

4、启动微服务8401

5、启动8401微服务后查看

此时要先发送一个请求： http://localhost:8401/testA

Sentinel控制台才能检测到该微服务