【SpringCloud AlibabaSentinel实现熔断与限流】

本笔记内容为尚硅谷SpringCloud AlibabaSentinel部分 

目录

一、Sentinel

1、官网

2、Sentinel是什么

3、下载

4、特性

5、使用

二、安装Sentinel控制台 

1、sentinel组件由2部分构成

2、安装步骤

1.下载

2.运行命令

3.访问sentinel管理界面

三、初始化演示工程

四、流控规则

1、基本介绍

解释说明

2、流控模式

1.直接(默认)

2.关联

3.链路

3、流控效果

1.直接->快速失败(默认的流控处理)

2.预热

3.排队等待 

五、降级规则

1、基本介绍

2、降级策略实战

1.RT

2.异常比例

3.异常数

六、热点key限流

1、基本介绍

2、测试代码

3、配置

4、参数例外项

配置

七、系统规则 

各项配置参数说明 

八、@SentinelResource 

1、按资源名称限流+后续处理

2、按照Url地址限流+后续处理 

3、客户自定义限流处理逻辑 

4、更多注解属性说明

九、服务熔断功能 

1、Ribbon系列

2、Feign系列

3、熔断框架比较

十、规则持久化

步骤 

---

一、Sentinel

---

1、官网

https://github.com/alibaba/Sentinel

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

2、Sentinel是什么

类似之前学过的Hystrix

3、下载

Releases · alibaba/Sentinel · GitHub

4、特性

5、使用

查看官网：Spring Cloud Alibaba Reference Documentation

服务使用中的各种问题

• 服务雪崩
• 服务降级
• 服务熔断
• 服务限流

二、安装Sentinel控制台 

---

1、sentinel组件由2部分构成

后台+前台8080

2、安装步骤

1.下载

Releases · alibaba/Sentinel · GitHub

下载到本地sentinel-dashboard-1.7.0.jar

2.运行命令

前提：java8环境正常，8080端口不能被占用

命令：java -jar sentinel-dashboard-1.7.0.jar

3.访问sentinel管理界面

http://localhost:8080，登录账号密码均为sentinel

三、初始化演示工程

---

1、启动Nacos8848成功

http://localhost:8848/nacos/#/login

2、Module

cloudalibaba-sentinel-service8401

3、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>cloud190805</artifactId><groupId>com.atguigu.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>cloudalibaba-sentinel-service8401</artifactId><dependencies><!--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></project>

4、YML

server:port: 8401spring:application:name: cloudalibaba-sentinel-servicecloud:nacos:discovery:#Nacos服务注册中心地址server-addr: localhost:8848sentinel:transport:#配置Sentinel dashboard地址dashboard: localhost:8080#默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口port: 8719management:endpoints:web:exposure:include: '*'

5、主启动

package com.atguigu.springcloud.alibaba;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{public static void main(String[] args) {SpringApplication.run(MainApp8401.class, args);}
}

6、业务类FlowLimitController

package com.atguigu.springcloud.alibaba.controller;import com.atguigu.springcloud.alibaba.service.OrderService;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;@RestController
public class FlowLimitController
{@GetMapping("/testA")public String testA(){return "------testA";}@GetMapping("/testB")public String testB(){return "------testB";}
}

启动Sentinel8080 cmd ：java -jar sentinel-dashboard-1.7.0.jar

启动微服务8401

启动8401微服务后查看sentienl控制台，发现什么都没有

Sentinel采用的懒加载说明

执行一次访问即可（http://localhost:8401/testA 和 http://localhost:8401/testB）

效果

结论：sentinel8080正在监控微服务8401

四、流控规则

---

1、基本介绍

解释说明

2、流控模式

1.直接(默认)

直接->快速失败（系统默认）

配置及说明

2.关联

当关联的资源达到阈值时，就限流自己

当与A关联的资源B达到阀值后，就限流A自己、B惹事，A挂了

配置A

postman模拟并发密集访问testB

访问testB成功

postman里新建多线程集合组

将访问地址添加进新新线程组

Run（大批量线程高并发访问B，导致A失效了）

运行后发现testA挂了，点击访问http://localhost:8401/testA，结果Blocked by Sentinel (flow limiting)

3.链路

多个请求调用了同一个微服务（可以想象当作VIP通道）

3、流控效果

1.直接->快速失败(默认的流控处理)

2.预热

公式：阈值除以coldFactor(默认值为3),经过预热时长后才会达到阈值

官网：流量控制 · alibaba/Sentinel Wiki · GitHub

默认coldFactor为3，即请求 QPS 从 threshold / 3 开始，经预热时长逐渐升至设定的 QPS 阈值。

限流 冷启动：限流 冷启动 · alibaba/Sentinel Wiki · GitHub

WarmUp配置

多次点击http://localhost:8401/testB、刚开始不行，后续慢慢OK

应用场景

如：秒杀系统在开启的瞬间，会有很多流量上来，很有可能把系统打死，预热方式就是把为了保护系统，可慢慢的把流量放进来，慢慢的把阀值增长到设置的阀值。

3.排队等待 

官网：https://github.com/alibaba/Sentinel/wiki/%E6%B5%81%E9%87%8F%E6%8E%A7%E5%88%B6

测试

五、降级规则

---

官网：熔断降级 · alibaba/Sentinel Wiki · GitHub

1、基本介绍

RT（平均响应时间，秒级）

      平均响应时间   超出阈值  且   在时间窗口内通过的请求>=5，两个条件同时满足后触发降级

      窗口期过后关闭断路器

      RT最大4900（更大的需要通过-Dcsp.sentinel.statistic.max.rt=XXXX才能生效）

 

异常比列（秒级）

    QPS >= 5 且异常比例（秒级统计）超过阈值时，触发降级；时间窗口结束后，关闭降级

 

异常数（分钟级）

     异常数（分钟统计）超过阈值时，触发降级；时间窗口结束后，关闭降级

Sentinel 熔断降级会在调用链路中某个资源出现不稳定状态时（例如调用超时或异常比例升高），对这个资源的调用进行限制，让请求快速失败，避免影响到其它的资源而导致级联错误。

当资源被降级后，在接下来的降级时间窗口之内，对该资源的调用都自动熔断（默认行为是抛出 DegradeException）。

Sentinel的断路器是没有半开状态的

半开的状态系统自动去检测是否请求有异常，没有异常就关闭断路器恢复使用，有异常则继续打开断路器不可用。具体可以参考Hystrix

2、降级策略实战

1.RT

 

测试

@GetMapping("/testD")
public String testD()
{//暂停几秒钟线程try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }log.info("testD 测试RT");return "------testD";
}

配置

jmeter压测

结论：

永远一秒钟打进来10个线程（大于5个了）调用testD，我们希望200毫秒处理完本次任务，

如果超过200毫秒还没处理完，在未来1秒钟的时间窗口内，断路器打开(保险丝跳闸)微服务不可用，保险丝跳闸断电了

后续我停止jmeter，没有这么大的访问量了，断路器关闭(保险丝恢复)，微服务恢复OK

2.异常比例

测试

@GetMapping("/testD")
public String testD()
{log.info("testD 测试RT");int age = 10/0;return "------testD";
}

配置

jmeter

结论

3.异常数

异常数是按照分钟统计的

测试

@GetMapping("/testE")
public String testE()
{log.info("testE 测试异常比例");int age = 10/0;return "------testE 测试异常比例";
}

配置

jmeter

六、热点key限流

---

1、基本介绍

官网：https://github.com/alibaba/Sentinel/wiki/热点参数限流

2、测试代码

@SentinelResource

@GetMapping("/testHotKey")
@SentinelResource(value = "testHotKey",blockHandler = "dealHandler_testHotKey")
public String testHotKey(@RequestParam(value = "p1",required = false) String p1, @RequestParam(value = "p2",required = false) String p2){return "------testHotKey";
}
public String dealHandler_testHotKey(String p1,String p2,BlockException exception)
{return "-----dealHandler_testHotKey";
}

3、配置

限流模式只支持QPS模式，固定写死了。（这才叫热点）

@SentinelResource注解的方法参数索引，0代表第一个参数，1代表第二个参数，以此类推

单机阀值以及统计窗口时长表示在此窗口时间超过阀值就限流。

上面的抓图就是第一个参数有值的话，1秒的QPS为1，超过就限流，限流后调用dealHandler_testHotKey支持方法。

测试

4、参数例外项

上述案例演示了第一个参数p1，当QPS超过1秒1次点击后马上被限流

配置

 

@SentinelResource

处理的是Sentinel控制台配置的违规情况，有blockHandler方法配置的兜底处理；

 

RuntimeException

int age = 10/0,这个是java运行时报出的运行时异常RunTimeException，@SentinelResource不管

总结

 @SentinelResource主管配置出错，运行出错该走异常走异常

七、系统规则 

---

官网：系统自适应限流 · alibaba/Sentinel Wiki · GitHub

各项配置参数说明 

八、@SentinelResource 

---

1、按资源名称限流+后续处理

启动Nacos成功：http://localhost:8848/nacos/#/login

启动Sentinel成功：java -jar sentinel-dashboard-1.7.0.jar

Module

1.新建cloudalibaba-sentinel-service8401

2.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>mscloud03</artifactId><groupId>com.atguigu.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>cloudalibaba-sentinel-service8401</artifactId><dependencies><!--SpringCloud ailibaba nacos --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><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 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></project>

3.YML

server:port: 8401spring:application:name: cloudalibaba-sentinel-servicecloud: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port: 8719management:endpoints:web:exposure:include: '*'

4.业务类RateLimitController

package com.atguigu.springcloud.alibaba.controller;import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class RateLimitController
{@GetMapping("/byResource")@SentinelResource(value = "byResource",blockHandler = "handleException")public CommonResult byResource(){return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));}public CommonResult handleException(BlockException exception){return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");}
}

5.主启动

package com.atguigu.springcloud.alibaba;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{public static void main(String[] args) {SpringApplication.run(MainApp8401.class, args);}
}

配置流控规则

图形配置和代码关系（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）

额外问题：此时关闭问服务8401看看，Sentinel控制台，流控规则消失了-临时（见第十的规则持久化）

2、按照Url地址限流+后续处理 

通过访问的URL来限流，会返回Sentinel自带默认的限流处理信息

业务类RateLimitController

package com.atguigu.springcloud.alibaba.controller;import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class RateLimitController
{@GetMapping("/byResource")@SentinelResource(value = "byResource",blockHandler = "handleException")public CommonResult byResource(){return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));}public CommonResult handleException(BlockException exception){return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");}@GetMapping("/rateLimit/byUrl")@SentinelResource(value = "byUrl")public CommonResult byUrl(){return new CommonResult(200,"按url限流测试OK",new Payment(2020L,"serial002"));}
}

访问：http://localhost:8401/rateLimit/byUrl

Sentinel控制台配置 

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。

3、客户自定义限流处理逻辑 

创建CustomerBlockHandler类用于自定义限流处理逻辑

1.自定义限流处理类CustomerBlockHandler

package com.atguigu.springcloud.alibaba.myhandler;import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.springcloud.alibaba.entities.CommonResult;
import org.springframework.stereotype.Component;public class CustomerBlockHandler
{public static CommonResult handleException(BlockException exception){return new CommonResult(2020,"自定义的限流处理信息......CustomerBlockHandler");}
}

2.RateLimitController

启动微服务后先调用一次http://localhost:8401/rateLimit/customerBlockHandler

3.Sentinel控制台配置 

测试后我们自定义的出来了

4、更多注解属性说明

 

九、服务熔断功能 

---

sentinel整合ribbon+openFeign+fallback

1、Ribbon系列

1.启动nacos和sentinel

2.提供者9003/9004

新建cloudalibaba-provider-payment9003/9004两个一样的做法

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>mscloud03</artifactId><groupId>com.atguigu.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>cloudalibaba-provider-payment9003</artifactId><dependencies><!--SpringCloud ailibaba nacos --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><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><!-- SpringBoot整合Web组件 --><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>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>
</project>

YML（记得修改不同的端口号）

server:port: 9003spring:application:name: nacos-payment-providercloud:nacos:discovery:server-addr: localhost:8848 #配置Nacos地址management:endpoints:web:exposure:include: '*'

主启动

package com.atguigu.springcloud.alibaba;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain9003
{public static void main(String[] args) {SpringApplication.run(PaymentMain9003.class, args);}
}

业务类

package com.atguigu.springcloud.alibaba.controller;import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;import java.util.HashMap;
@RestController
public class PaymentController
{@Value("${server.port}")private String serverPort;public static HashMap<Long,Payment> hashMap = new HashMap<>();static{hashMap.put(1L,new Payment(1L,"28a8c1e3bc2742d8848569891fb42181"));hashMap.put(2L,new Payment(2L,"bba8c1e3bc2742d8848569891ac32182"));hashMap.put(3L,new Payment(3L,"6ua8c1e3bc2742d8848569891xt92183"));}@GetMapping(value = "/paymentSQL/{id}")public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id){Payment payment = hashMap.get(id);CommonResult<Payment> result = new CommonResult(200,"from mysql,serverPort:  "+serverPort,payment);return result;}}

测试地址：http://localhost:9003/paymentSQL/1

3.消费者84

新建cloudalibaba-consumer-nacos-order84

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>mscloud03</artifactId><groupId>com.atguigu.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>cloudalibaba-consumer-nacos-order84</artifactId><dependencies><!--SpringCloud ailibaba nacos --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--SpringCloud ailibaba sentinel --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity --><dependency><groupId>com.atguigu.springcloud</groupId><artifactId>cloud-api-commons</artifactId><version>${project.version}</version></dependency><!-- SpringBoot整合Web组件 --><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>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>
</project>

YML

server:port: 84spring:application:name: nacos-order-consumercloud:nacos:discovery:server-addr: localhost:8848sentinel:transport:#配置Sentinel dashboard地址dashboard: localhost:8080#默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口port: 8719#消费者将要去访问的微服务名称(注册成功进nacos的微服务提供者)
service-url:nacos-user-service: http://nacos-payment-provider

主启动

package com.atguigu.springcloud.alibaba;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;@EnableDiscoveryClient
@SpringBootApplication
public class OrderNacosMain84
{public static void main(String[] args) {SpringApplication.run(OrderNacosMain84.class, args);}
}

业务类

ApplicationContextConfig

package com.atguigu.springcloud.alibaba.config;import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;@Configuration
public class ApplicationContextConfig
{@Bean@LoadBalancedpublic RestTemplate getRestTemplate(){return new RestTemplate();}
}

CircleBreakerController​

 

fallback和blockHandler都配置

编码

package com.atguigu.springcloud.alibaba.controller;import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;import javax.annotation.Resource;
import java.sql.SQLException;
import java.util.concurrent.Executors;@RestController
@Slf4j
public class CircleBreakerController
{public static final String SERVICE_URL = "http://nacos-payment-provider";@Resourceprivate RestTemplate restTemplate;@RequestMapping("/consumer/fallback/{id}")@SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler")public CommonResult<Payment> fallback(@PathVariable Long id){CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);if (id == 4) {throw new IllegalArgumentException ("非法参数异常....");}else if (result.getData() == null) {throw new NullPointerException ("NullPointerException,该ID没有对应记录");}return result;}public CommonResult handlerFallback(@PathVariable  Long id,Throwable e) {Payment payment = new Payment(id,"null");return new CommonResult<>(444,"fallback,无此流水,exception  "+e.getMessage(),payment);}public CommonResult blockHandler(@PathVariable  Long id,BlockException blockException) {Payment payment = new Payment(id,"null");return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException  "+blockException.getMessage(),payment);}}

sentinel需配置

结果 

忽略属性

程序异常打到前台了，对用户不友好 

2、Feign系列

2.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>mscloud03</artifactId><groupId>com.atguigu.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>cloudalibaba-consumer-nacos-order84</artifactId><dependencies><!--SpringCloud ailibaba nacos --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--SpringCloud ailibaba sentinel --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency><!--SpringCloud openfeign --><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity --><dependency><groupId>com.atguigu.springcloud</groupId><artifactId>cloud-api-commons</artifactId><version>${project.version}</version></dependency><!-- SpringBoot整合Web组件 --><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>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>
</project>

3.YML（激活Sentinel对Feign的支持）

server:port: 84spring:application:name: nacos-order-consumercloud:nacos:discovery:#Nacos服务注册中心地址server-addr: localhost:8848sentinel:transport:#配置Sentinel dashboard地址dashboard: localhost:8080#默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口port: 8719management:endpoints:web:exposure:include: '*'
# 激活Sentinel对Feign的支持
feign:sentinel:enabled: true  

4.业务类

带@FeignClient注解的业务接口（定义接口）

package com.atguigu.springcloud.alibaba.service;import com.atguigu.springcloud.alibaba.entities.CommonResult;
import com.atguigu.springcloud.alibaba.entities.Payment;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;/*** 使用 fallback 方式是无法获取异常信息的，* 如果想要获取异常信息，可以使用 fallbackFactory参数*/
@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)//调用中关闭9003服务提供者
public interface PaymentService
{@GetMapping(value = "/paymentSQL/{id}")public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id);
}

fallback = PaymentFallbackService.class（实现类）

package com.atguigu.springcloud.alibaba.service;import com.atguigu.springcloud.alibaba.entities.CommonResult;
import com.atguigu.springcloud.alibaba.entities.Payment;
import org.springframework.stereotype.Component;@Component
public class PaymentFallbackService implements PaymentService
{@Overridepublic CommonResult<Payment> paymentSQL(Long id){return new CommonResult<>(444,"服务降级返回,没有该流水信息",new Payment(id, "errorSerial......"));}
}

5.Controller

package com.atguigu.springcloud.alibaba.controller;import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;import javax.annotation.Resource;@RestController
@Slf4j
public class CircleBreakerController
{public static final String SERVICE_URL = "http://nacos-payment-provider";@Resourceprivate RestTemplate restTemplate;@RequestMapping("/consumer/fallback/{id}")//@SentinelResource(value = "fallback") //没有配置//@SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback只负责业务异常//@SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler只负责sentinel控制台配置违规@SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler",exceptionsToIgnore = {IllegalArgumentException.class})public CommonResult<Payment> fallback(@PathVariable Long id){CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);if (id == 4) {throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常....");}else if (result.getData() == null) {throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常");}return result;}//本例是fallbackpublic CommonResult handlerFallback(@PathVariable  Long id,Throwable e) {Payment payment = new Payment(id,"null");return new CommonResult<>(444,"兜底异常handlerFallback,exception内容  "+e.getMessage(),payment);}//本例是blockHandlerpublic CommonResult blockHandler(@PathVariable  Long id,BlockException blockException) {Payment payment = new Payment(id,"null");return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException  "+blockException.getMessage(),payment);}//==================OpenFeign@Resourceprivate PaymentService paymentService;@GetMapping(value = "/consumer/openfeign/{id}")public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id){if(id == 4){throw new RuntimeException("没有该id");}return paymentService.paymentSQL(id);}}

6.主启动

添加@EnableFeignClients启动Feign的功能

package com.atguigu.springcloud.alibaba;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class OrderNacosMain84
{public static void main(String[] args) {SpringApplication.run(OrderNacosMain84.class, args);}
}

3、熔断框架比较

十、规则持久化

---

一旦我们重启应用，sentinel规则将消失，生产环境需要将配置规则进行持久化

将限流配置规则持久化进Nacos保存，只要刷新8401某个rest地址，sentinel控制台的流控规则就能看到，只要Nacos里面的配置不删除，针对8401上sentinel上的流控规则持续有效

步骤 

1.修改cloudalibaba-sentinel-service8401

2.POM引入持久化依赖

<!--SpringCloud ailibaba sentinel-datasource-nacos -->
<dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-datasource-nacos</artifactId>
</dependency>

3.YML

添加Nacos数据源配置

server:port: 8401spring:application:name: cloudalibaba-sentinel-servicecloud: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port: 8719datasource:ds1:nacos:server-addr: localhost:8848dataId: cloudalibaba-sentinel-servicegroupId: DEFAULT_GROUPdata-type: jsonrule-type: flowmanagement:endpoints:web:exposure:include: '*'feign:sentinel:enabled: true # 激活Sentinel对Feign的支持

4.添加Nacos业务规则配置

5.启动8401后刷新sentinel发现业务规则有了

6.快速访问测试接口

7.停止8401再看sentinel

 结束！