【SpringCloudAlibaba】Sentinel监控工具@SentinelResource练习，实现自己的兜底策略

前言

本篇博客主要是向大家介绍：@SentinelResource ，它用于定义资源，并提供可选的异常处理和 fallback 配置项。 通过demo演示，为大家介绍相关的属性。

---

按资源名称限流

• 启动Nacos成功
  
• 启动Sentinel成功
  
• pom

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>com.zcw.springcloud2020508</artifactId>
        <groupId>com.zcw</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloudalibaba-sentinel-service8401</artifactId>

    <dependencies>
        <dependency>
            <groupId>com.zcw</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <!--SpringCloud alibaba nacos-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--SpringCloud alibaba sentinel-datasource-nacos 后续做持久化用到-->
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-datasource-nacos</artifactId>
        </dependency>
        <!--SpringCloud alibaba 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-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</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>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

• 创建Controller类

package com.zcw.springcloud.alibaba.controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.zcw.springcloud.entities.CommonResult;
import com.zcw.springcloud.entities.Payment;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @ClassName : RateLimitController
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-05-28 09:36
 */
@RestController
public class RateLimitController {
    @GetMapping("/byResource")
    @SentinelResource(value = "byResource",blockHandler = "handleException")
    public CommonResult byResource(){
        return new CommonResult(200,"按自愿名称限流测试OK",
                new Payment(2020L,"serial001"));
    }
    public CommonResult handleException(BlockException blockException){
        return new CommonResult(444,blockException.getClass().getCanonicalName()+"\t服务不可用");
    }
}

• 配置流控规则：

• 连续点击时，出现如下图所示：
  
  表示1秒钟内查询次数大于1，就跑到我们自定义的处流，限流
• 关闭8401服务测试一下下：
  
  
  竟然是临时的。。。。

按照Url地址限流

通过访问的URL来限流，会返回Sentinel自带默认的限流处理信息。

 @GetMapping("/rateLimit/byUrl")
    @SentinelResource(value = "byUrl")
    public CommonResult byUrl(){
        return new CommonResult(200,"按url限流测试OK",new Payment(2020L,"serial002"));
    }

• 修改我们Sentinel控制台
  
  
  疯狂点击会报如下错误：
  
• 竟然没有返回：如下结果，百思不得其解
  

上面兜底方案面临的问题

1.系统默认的，没有体现我们自己的业务要求
2.依照现有条件，我们自定义的处理方法又和业务代码耦合在一块，不直观。
3.每个业务方法都添加一个兜底的，那代码膨胀加剧。
4.全局统一的处理方法没有体现。

自定义限流处理逻辑

• 创建CustomerBlockHandler类用于自定义限流处理逻辑
  【自定义限流处理类 CustomerBlockHandler】

package com.zcw.springcloud.alibaba.myhandler;

import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.zcw.springcloud.entities.CommonResult;
import com.zcw.springcloud.entities.Payment;

/**
 * @ClassName : CustomerBlockHandler
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-05-28 10:18
 */
public class CustomerBlockHandler {
    public static CommonResult handlerException(BlockException blockException){
        return  new CommonResult(444,"自定义");
    }
}

• RateLimitController
  

 @GetMapping("/rateLimit/customerBlockHandler")
    @SentinelResource(value = "customerBlockHandler",
            blockHandlerClass = CustomerBlockHandler.class,
            blockHandler = "handlerException")
    public CommonResult customerBlockHandler(){
        return new CommonResult(200,"自定义限流规则",new Payment(2020L,"serial002"));
    }

• Sentinel控制台配置
  
  
  
• 测试
  
  
• 进一步说明，我们可以配置多个兜底的方法：
  

属性说明讲解

下面是官方地址：
https://github.com/alibaba/Sentinel/wiki/%E6%B3%A8%E8%A7%A3%E6%94%AF%E6%8C%81

Sentinel主要有三个核心的API

• SphU定义资源
• Tracer定义统计
• ContextUtil定义了上下文