Sentinel HelloWorld实现

╰+攻爆jí腚メ 2021-09-07 15:14 326阅读 0赞

[**完整Sentinel目录清单页面（必看）**][Sentinel]

## **第一步：创建项目，引入依赖** ##

为了方便后期sentinel和springcloud以及springcloud alibaba其他组件整合开发讲解，我们这边规范好springboot，springcloud，springcloud alibaba的版本，选用稳定的组合版本；

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nhb2xpMjAxMzE0_size_16_color_FFFFFF_t_70]

具体查看：https://github.com/alibaba/spring-cloud-alibaba/wiki/%E7%89%88%E6%9C%AC%E8%AF%B4%E6%98%8E

先创建父pom项目 **sentinel-test**

属性，依赖管理以及插件定义；

<properties>
    	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    	<maven.compiler.source>1.8</maven.compiler.source>
    	<maven.compiler.target>1.8</maven.compiler.target>
    	<spring-cloud.version>Hoxton.SR8</spring-cloud.version>
    	<springboot.version>2.3.2.RELEASE</springboot.version>
    	<springcloudalibaba.version>2.2.4.RELEASE</springcloudalibaba.version>
    </properties>
    
    <dependencyManagement>
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-dependencies</artifactId>
    			<version>${spring-cloud.version}</version>
    			<type>pom</type>
    			<scope>import</scope>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-dependencies</artifactId>
    			<version>${springboot.version}</version>
    			<type>pom</type>
    			<scope>import</scope>
    		</dependency>
    		<dependency>
    			<groupId>com.alibaba.cloud</groupId>
    			<artifactId>spring-cloud-alibaba-dependencies</artifactId>
    			<version>${springcloudalibaba.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>

新建module项目 **sentinel-helloworld**

引入web和sentinel依赖

<dependencies>
    	<dependency>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-web</artifactId>
    	</dependency>
    
    	<dependency>
    		<groupId>com.alibaba.csp</groupId>
    		<artifactId>sentinel-core</artifactId>
    	</dependency>
    </dependencies>

application.yml配置

server:
      port: 80
      servlet:
          context-path: "/"

新建启动类：**SentinelHelloWorldApplication**

package com.java1234;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    /** * @author java1234_小锋 * @site www.java1234.com * @company Java知识分享网 * @create 2021-05-04 15:18 */
    @SpringBootApplication
    public class SentinelHelloWorldApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(SentinelHelloWorldApplication.class,args);
        }
    }

## **第二步：定义规则和使用限流规则** ##

package com.java1234.controller;
    
    import com.alibaba.csp.sentinel.Entry;
    import com.alibaba.csp.sentinel.SphU;
    import com.alibaba.csp.sentinel.slots.block.RuleConstant;
    import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
    import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import javax.annotation.PostConstruct;
    import java.util.ArrayList;
    import java.util.List;
    
    /** * @author java1234_小锋 * @site www.java1234.com * @company Java知识分享网 * @create 2021-05-04 14:35 */
    @RestController
    public class SentinelHelloWorld { 
    
    
        @RequestMapping("helloWorld")
        public String helloWorld(){ 
            try(Entry entry=SphU.entry("HelloWorld")){  // 使用限流规则 HelloWorld
                return "Sentinel 大爷你好！"+System.currentTimeMillis();
            }catch (Exception e){ 
                e.printStackTrace();
                return "系统繁忙，请稍后！";  // 降级处理
            }
        }
    
        /** * 定义限流规则 * PostConstruct 构造方法执行完后执行方法 定义和加载限流规则 */
        @PostConstruct
        public void initFlowRules(){ 
            List<FlowRule> rules=new ArrayList<>(); // 定义限流规则集合
            FlowRule rule=new FlowRule();  // 定义限流规则
            rule.setResource("HelloWorld");  // 定义限流资源
            rule.setGrade(RuleConstant.FLOW_GRADE_QPS); // 定义限流规则类型
            rule.setCount(2); // 定义QPS阈值 每秒最多通过的请求个数
            rules.add(rule);  // 添加规则到集合
            FlowRuleManager.loadRules(rules); // 加载规则集合
        }
    }

## **第三步：测试** ##

浏览器请求：http://localhost/helloWorld

正常请求：

![在这里插入图片描述][20210507212832872.png]

当访问频率超过QPS阈值2，则sentinel降级返回异常信息；

![在这里插入图片描述][20210507212846382.png]

测试通过；

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[Sentinel]: https://blog.csdn.net/caoli201314/article/details/116422933
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nhb2xpMjAxMzE0_size_16_color_FFFFFF_t_70]: /images/20210716/c63b89e303c2414a912c7a443d7a4ef6.png
[20210507212832872.png]: /images/20210716/96222bee38ae4735a82c444bf029c16e.png
[20210507212846382.png]: /images/20210716/46136f87de264ecea0e1537c5cc2efdf.png