用Sentinel实现项目的直接限流

1、使用Spring Initializr创建Spring Boot 工程

Pom.xml：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.tyschool</groupId>
    <artifactId>sentinel-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>sentinel-demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud-alibaba.version>2.2.1.RELEASE</spring-cloud-alibaba.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
       <!--Sentinel依赖-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>
        <!--actuator依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>${spring-cloud-alibaba.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>

    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
        <repository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </pluginRepository>
        <pluginRepository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>

</project>

2、添加配置

在application.properties文件中配置:

spring.application.name=Sentinel Demo
server.port=8088
# sentinel dashboard 指定sentinel 控制台地址
spring.cloud.sentinel.transport.dashboard=localhost:8080
# 暴露出所有actuator监控的端点
management.endpoints.web.exposure.include=*

3、限流埋点

限流埋点可以通过HTTP埋点和自定义埋点两种方式实现。

3.1、HTTP埋点

Sentinel的Starter默认为所有的HTTP服务提供了限流埋点。如果只想对某个HTTP服务进行限流，则只需要引入依赖，无须修改代码

3.2、自定义埋点

如果需要对某个特定的服务进行限流或降级，则可以通过注解@SentienlResource来完成

3.3、添加自定义埋点

@SpringBootApplication
public class SentinelDemoApplication {

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

	@RestController
	public class TestController{

		@GetMapping("/hello")
		@SentinelResource("hello")
		public String hello(){
			return "Hello Sentinel Demo!";
		}
	}
}

4、创建快速失败的直接限流模式

5、测试快速访问失败的直接限流模式

多次快速访问 http://localhost:8088/hello,当QPS超过2时，直接返回页面错误