[Java知识库]SpringCloud 第十九章 SpringCloud Alibaba Sentinel实现熔断与限流

一、Sentinel

官网

中文

1、是什么

一句话解释，之前我们讲解过的Hystrix

2、去哪下

下载

3、能干嘛

4、怎么玩

文档

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

下载到本地sentinel-dashboard-1.7.0.jar

2、运行命令

1、前提

java8环境OK
8080端口不能被占用

2、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

1、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>cloud2020</artifactId>
        <groupId>org.example</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>

3、YML

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        #Nacos服务注册中心地址
        server-addr: localhost:8848
    sentinel:
      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

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

4、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;

/**
 * @author String-int
 * @create 2022-05-02 14:54
 */
@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }
}

5、业务类FlowLimitController

package com.atguigu.springcloud.alibaba.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author String-int
 * @create 2022-05-02 14:55
 */
@RestController
public class FlowLimitController
{

    @GetMapping("/testA")
    public String testA()
    {
        return "------testA";
    }

    @GetMapping("/testB")
    public String testB()
    {
        return "------testB";
    }
}

3、启动Sentinel8080

java -jar sentinel-dashboard-1.7.2.jar

4、启动微服务8401

5、启动8401微服务后查看sentienl控制台

1、空空如也，啥都没有

2、Sentinel采用的懒加载说明

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

效果

3、结论

sentinel8080正在监控微服务8401

四、流控规则

1、基本介绍

进一步解释说明

2、流控模式

1、直接(默认)

1、直接->快速失败

系统默认

2、配置及说明

表示1秒钟内查询1次就是OK，若超过次数1，就直接-快速失败，报默认错误

3、测试

1、快速点击访问http://localhost:8401/testA

2、结果

Blocked by Sentinel (flow limiting)

3、思考???
直接调用默认报错信息，技术方面OK
but,是否应该有我们自己的后续处理?
类似有个fallback的兜底方法？

2、关联

1、是什么

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

2、配置A

设置效果
当关联资源/testB的qps阀值超过1时，就限流/testA的Rest访问地址，当关联资源到阈值后限制配置好的资源名

3、postman模拟并发密集访问testB

1、访问testB成功

2、postman里新建多线程集合组

3、将访问地址添加进新新线程组

4、Run

大批量线程高并发访问B，导致A失效了

4、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

3、流控效果

1、直接->快速失败(默认的流控处理)

1、直接失败，抛出异常

Blocked by Sentinel (flow limiting)

2、源码
com.alibaba.csp.sentinel.slots.block.flow.controller.DefaultController

2、预热

1、说明

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

2、官网
官网

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
3、源码
com.alibaba.csp.sentinel.slots.block.flow.controller.WarmUpController

4、WarmUp配置

默认 coldFactor 为 3，即请求QPS从(threshold / 3) 开始，经多少预热时长才逐渐升至设定的 QPS 阈值。
案例，阀值为10+预热时长设置5秒。
系统初始化的阀值为10 / 3 约等于3,即阀值刚开始为3；然后过了5秒后阀值才慢慢升高恢复到10

5、多次点击http://localhost:8401/testB

刚开始不行，后续慢慢OK

6、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

匀速排队，让请求以均匀的速度通过，阀值类型必须设成QPS，否则无效。
设置含义：/testA每秒1次请求，超过的话就排队等待，等待的超时时间为20000毫秒。

1、匀速排队，阈值必须设置为QPS
2、官网
3、源码

com.alibaba.csp.sentinel.slots.block.flow.controller.RateLimiterController

4、测试

五、降级规则

1、官网

2、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

1、进一步说明

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）。

2、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

复习Hystrix

3、降级策略实战

1、RT

1、是什么

2、测试

1、代码

@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";
}

2、配置

3、jmeter压测

4、结论

按照上述配置，

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

1、是什么

2、测试

1、代码

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

2、配置

3、jmeter压测

4、结论
按照上述配置，
单独访问一次，必然来一次报错一次(int age = 10/0)，调一次错一次；

开启jmeter后，直接高并发发送请求，多次调用达到我们的配置条件了。
断路器开启(保险丝跳闸)，微服务不可用了，不再报错error而是服务降级了。

3、异常数

1、是什么

时间窗口一定要大于等于60秒。

2、异常数是按照分钟统计的

3、测试

1、代码

@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";
}

2、配置

http://localhost:8401/testE，第一次访问绝对报错，因为除数不能为零，
我们看到error窗口，但是达到5次报错后，进入熔断后降级。

3、jmeter压测

六、热点key限流

1、基本介绍

2、官网

3、承上启下复习start

兜底方法
分为系统默认和客户自定义，两种

之前的case，限流出问题后，都是用sentinel系统默认的提示：Blocked by Sentinel (flow limiting)

我们能不能自定?类似hystrix，某个方法出问题了，就找对应的兜底降级方法？

结论
从HystrixCommand 到@SentinelResource

@SentinelResource

4、代码

com.alibaba.csp.sentinel.slots.block.BlockException

@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";
}
 
 
 sentinel系统默认的提示：Blocked by Sentinel (flow limiting)

5、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。

配置：
1、

@SentinelResource(value = “testHotKey”)
异常打到了前台用户界面看到，不友好

2、

@SentinelResource(value = “testHotKey”,blockHandler = “dealHandler_testHotKey”)
方法testHotKey里面第一个参数只要QPS超过每秒1次，马上降级处理

用了我们自己定义的

6、测试

1、error
http://localhost:8401/testHotKey?p1=abc
2、error
http://localhost:8401/testHotKey?p1=abc&p2=33
3、right
http://localhost:8401/testHotKey?p2=abc

7、参数例外项

1、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

2、特例情况

1、普通：
超过1秒钟一个后，达到阈值1后马上被限流

2、我们期望p1参数当它是某个特殊值时，它的限流值和平时不一样

3、特例：
假如当p1的值等于5时，它的阈值可以达到200

3、配置

添加按钮不能忘

4、测试

对的：http://localhost:8401/testHotKey?p1=5

错的：http://localhost:8401/testHotKey?p1=3

当p1等于5的时候，阈值变为200

当p1不等于5的时候，阈值就是平常的1

5、前提条件

热点参数的注意点，参数必须是基本类型或者String

8、其它

手贱添加异常看看…/(ㄒoㄒ)/~~

后面讲

@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

1、是什么

2、各项配置参数说明

3、配置全局QPS

八、@SentinelResource

1、按资源名称限流+后续处理

1、启动Nacos成功

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

2、启动Sentinel成功

java -jar sentinel-dashboard-1.7.0.jar

3、Module

1、cloudalibaba-sentinel-service8401
2、POM

<!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

3、YML

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        #Nacos服务注册中心地址
        server-addr: localhost:8848
    sentinel:
      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

management:
  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;

/**
 * @author String-int
 * @create 2022-05-03 23:42
 */
@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;

/**
 * @author String-int
 * @create 2022-05-02 14:54
 */
@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }
}

4、配置流控规则

1、配置步骤

2、图形配置和代码关系

3、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

5、测试

http://localhost:8401/byResource

1秒钟点击1下，OK
超过上述，疯狂点击，返回了自己定义的限流处理信息，限流发生

6、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/持久？

2、按照Url地址限流+后续处理

1、通过访问的URL来限流，会返回Sentinel自带默认的限流处理信息
2、业务类RateLimitController

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

3、访问一次
http://localhost:8401/rateLimit/byUrl
4、Sentinel控制台配置

5、测试

疯狂点击http://localhost:8401/rateLimit/byUrl

结果
会返回Sentinel自带的限流处理结果

3、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。

4、客户自定义限流处理逻辑

1、创建CustomerBlockHandler类用于自定义限流处理逻辑

2、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.entities.CommonResult;

/**
 * @author String-int
 * @create 2022-05-04 0:00
 */
public class CustomerBlockHandler
{
    public static CommonResult handleException(BlockException exception){
        return new CommonResult(2020,"自定义的限流处理信息......CustomerBlockHandler");
    }
}

3、RateLimitController

/**
     * 自定义通用的限流处理逻辑，
     blockHandlerClass = CustomerBlockHandler.class
     blockHandler = handleException2
     上述配置：找CustomerBlockHandler类里的handleException2方法进行兜底处理
     */
    /**
     * 自定义通用的限流处理逻辑
     */
    @GetMapping("/rateLimit/customerBlockHandler")
    @SentinelResource(value = "customerBlockHandler",
            blockHandlerClass = CustomerBlockHandler.class, blockHandler = "handleException2")
    public CommonResult customerBlockHandler() {
        return new CommonResult(200, "按客户自定义限流处理逻辑");
    }

4、启动微服务后先调用一次

http://localhost:8401/rateLimit/customerBlockHandler

5、Sentinel控制台配置

6、测试后我们自定义的出来了

7、进一步说明

5、更多注解属性说明

1、多说一句

所有的代码都要用try-catch-finally方式进行处理，o(╥﹏╥)o

2、Sentinel主要有三个核心Api

SphU定义资源
Tracer定义统计
ContextUtil定义了上下文

九、服务熔断功能

1、sentinel整合ribbon+openFeign+fallback

2、Ribbon系列

1、启动nacos和sentinel

2、提供者9003/9004

1、新建cloudalibaba-provider-payment9003/9004两个一样的做法
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>cloud2020</artifactId>
        <groupId>org.example</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>
        <!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</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 记得修改不同的端口号

server:
  port: 9003

spring:
  application:
    name: nacos-payment-provider
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848 #配置Nacos地址

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

4、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;

/**
 * @author String-int
 * @create 2022-05-04 0:20
 */
@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain9003
{
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain9003.class, args);
    }
}

5、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;

/**
 * @author String-int
 * @create 2022-05-04 0:20
 */
@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;
    }



}

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

3、消费者84

1、新建cloudalibaba-consumer-nacos-order84

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>cloud2020</artifactId>
        <groupId>org.example</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>org.example</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</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

server:
  port: 84


spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      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

4、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;

/**
 * @author String-int
 * @create 2022-05-04 0:39
 */
@EnableDiscoveryClient
@SpringBootApplication
public class OrderNacosMain84
{
    public static void main(String[] args) {
        SpringApplication.run(OrderNacosMain84.class, args);
    }
}

5、业务类

CircleBreakerController

1、修改后请重启微服务

热部署对java代码级生效及时
对@SentinelResource注解内属性，有时效果不好

2、目的

fallback管运行异常
blockHandler管配置违规

3、测试地址

http://localhost:84/consumer/fallback/1

4、没有任何配置

给客户error页面，不友好

package com.atguigu.springcloud.alibaba.controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import lombok.extern.slf4j.Slf4j;
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;

/**
 * @author String-int
 * @create 2022-05-04 0:47
 */
@RestController
@Slf4j
public class CircleBreakerController
{
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private RestTemplate restTemplate;

    @RequestMapping("/consumer/fallback/{id}")
    @SentinelResource(value = "fallback")
    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;
    }
}

5、只配置fallback

1、编码

package com.atguigu.springcloud.alibaba.controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import lombok.extern.slf4j.Slf4j;
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;

/**
 * @author String-int
 * @create 2022-05-04 0:47
 */
@RestController
@Slf4j
public class CircleBreakerController
{
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private RestTemplate restTemplate;

    @RequestMapping("/consumer/fallback/{id}")
//    @SentinelResource(value = "fallback")
    @SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback负责业务异常
    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;
    }

    public 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);
    }

}

图说

本例sentinel无配置

2、结果

6、只配置blockHandler

1、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.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;

/**
 * @author String-int
 * @create 2022-05-04 0:47
 */
@RestController
@Slf4j
public class CircleBreakerController
{
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private RestTemplate restTemplate;

    @RequestMapping("/consumer/fallback/{id}")
//    @SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback负责业务异常
@RestController
@Slf4j
public class CircleBreakerController
{
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private RestTemplate restTemplate;

    @RequestMapping("/consumer/fallback/{id}")
     @SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler负责在sentinel里面配置的降级限流
    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);
    }

}

图说

本例sentinel需配置

异常超过2次后，断路器打开，断电跳闸，系统被保护

2、结果

7、fallback和blockHandler都配置

1、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.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;

/**
 * @author String-int
 * @create 2022-05-04 0:47
 */
@RestController
@Slf4j
public class CircleBreakerController
{
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private 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);
    }

}
 
 

图说

本例sentinel需配置

2、结果

若 blockHandler 和 fallback 都进行了配置，则被限流降级而抛出 BlockException 时只会进入 blockHandler 处理逻辑。

8、忽略属性…

1、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.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;

/**
 * @author String-int
 * @create 2022-05-04 0:47
 */
@RestController
@Slf4j
public class CircleBreakerController
{
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private RestTemplate restTemplate;

    @RequestMapping("/consumer/fallback/{id}")
@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 ("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);
    }
}
 
 
 

1、图说

2、本例sentinel无配置

2、结果
程序异常打到前台了，对用户不友好

3、Feign系列

1、修改84模块

84消费者调用提供者9003
Feign组件一般是消费侧

2、POM

<!--SpringCloud openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

3、YML

激活Sentinel对Feign的支持

# 激活Sentinel对Feign的支持
feign:
  sentinel:
    enabled: true  

server:
  port: 84


spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      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
# 激活Sentinel对Feign的支持
feign:
  sentinel:
    enabled: true  

4、业务类

1、带@FeignClient注解的业务接口

package com.atguigu.springcloud.alibaba.service;

import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

/**
 * @author String-int
 * @create 2022-05-04 1:31
 * 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);
}

2、fallback = PaymentFallbackService.class

package com.atguigu.springcloud.alibaba.service;

import com.atguigu.springcloud.entities.CommonResult;
import com.atguigu.springcloud.entities.Payment;
import org.springframework.stereotype.Component;

@Component
public class PaymentFallbackService implements PaymentService
{
    @Override
    public 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......"));
    }
}

3、Controller

//==================OpenFeign
    @Resource
    private 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);
    }

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.alibaba.service.PaymentService;
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;

/**
 * @author String-int
 * @create 2022-05-04 0:47
 */
@RestController
@Slf4j
public class CircleBreakerController
{
    public static final String SERVICE_URL = "http://nacos-payment-provider";

    @Resource
    private RestTemplate restTemplate;

    @RequestMapping("/consumer/fallback/{id}")
//    @SentinelResource(value = "fallback")//没有配置
//    @SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback负责业务异常
//    @SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler负责在sentinel里面配置的降级限流
      @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;
    }

    public 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);
    }

//    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);
    }


    //==================OpenFeign
    @Resource
    private 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);
    }

}

5、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;

/**
 * @author String-int
 * @create 2022-05-04 0:39
 */
@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients新加了这个注解
public class OrderNacosMain84
{
    public static void main(String[] args) {
        SpringApplication.run(OrderNacosMain84.class, args);
    }
}

6、http://localhost:84/consumer/paymentSQL/1

7、启动84和9003，测试84调用9003，此时故意关闭9003微服务提供者，看84消费侧自动降级，不会被耗死

4、熔断框架比较

十、规则持久化

1、是什么

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

2、怎么玩

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

3、步骤

1、修改cloudalibaba-sentinel-service8401

2、POM

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

3、YML

  datasource:
        ds1:
          nacos:
            server-addr: localhost:8848
            dataId: cloudalibaba-sentinel-service
            groupId: DEFAULT_GROUP
            data-type: json
            rule-type: flow

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
        port: 8719
      datasource:
        ds1:
          nacos:
            server-addr: localhost:8848
            dataId: cloudalibaba-sentinel-service
            groupId: DEFAULT_GROUP
            data-type: json
            rule-type: flow

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

feign:
  sentinel:
    enabled: true # 激活Sentinel对Feign的支持
 

添加Nacos数据源配置

 
spring:
  cloud:
    sentinel:
      datasource:
        ds1:
          nacos:
            server-addr: localhost:8848
            dataId: ${spring.application.name}
            groupId: DEFAULT_GROUP
            data-type: json
            rule-type: flow

4、添加Nacos业务规则配置

内容解析

 
[
    {
        "resource": "/rateLimit/byUrl",
        "limitApp": "default",
        "grade": 1,
        "count": 1,
        "strategy": 0,
        "controlBehavior": 0,
        "clusterMode": false
    }
]

 
resource：资源名称；
limitApp：来源应用；
grade：阈值类型，0表示线程数，1表示QPS；
count：单机阈值；
strategy：流控模式，0表示直接，1表示关联，2表示链路；
controlBehavior：流控效果，0表示快速失败，1表示Warm Up，2表示排队等待；
clusterMode：是否集群。
 
 
 
 

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

http://localhost:8401/rateLimit/byUrl
默认

7、停止8401再看sentinel

8、重新启动8401再看sentinel

乍一看还是没有，稍等一会儿

多次调用 http://localhost:8401/rateLimit/byUrl

重新配置出现了，持久化验证通过

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