1.下载sentinaljar包

2.启动jar包

cmd
java -jar sentinel-dashboard-1.8.1.jar

3.进入控制台

4.配置sentinel

5.在项目中引入sentinal

POM
<!--        sentinel依赖-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>

配置XML

XML
    sentinel:
      transport:
        dashboard: localhost:8070

6.配置sentinel

簇点链路

高级选项

(1)关联限流

当一个服务请求达到阈值对另一个服务做限制

案例

编写测试服务端点

java
    @GetMapping("query")
    public String queryOrderTest(){
        return "查询数据";
    }

    @GetMapping("update")
    public String updateOrderTest(){
        return "更新数据";
    }

发送请求使Sentinel监控服务端点

添加关联端点

模拟请求update，query被限流

(2)链路模式

只统计从指定链路访问本资源的请求

例子

java
// controller

    @GetMapping("query")
    public String queryOrderTest(){
        // 调用查询商品的方法
        orderService.queryGoods();
        System.out.println("查询订单");
        return "查询订单";
    }

    @GetMapping("save")
    public String saveOrderTest(){
        // 调用查询商品的方法
        orderService.queryGoods();
        System.out.println("新增订单");
        return "新增订单";
    }

java
// service 模拟查询数据

    public void queryGoods()
    {
        System.err.println("查询商品");
    }

修改sentinel监控关闭context整合

显示出service的方法

配置关联限制

(3)流控效果

决定请求失败时如何处理

配置 warn up

请求逐步通过

(4)排队等待

让进入的请求按照规定的时间间隔排队

(5)热点参数配置

例子

修改代码

java
    @SentinelResource("hot")  // 添加注解
    @GetMapping("{orderId}")
    public Order queryOrderByUserId(@PathVariable("orderId") Long orderId,@RequestHeader(value = "Truth",required = false) String truth) {
        System.out.println("truth"+truth);
        return orderService.queryOrderById(orderId);
    }

7.线程隔离和降级

(1)FegienClient整合Sentienl

线程隔离(舱闭模式) 熔断降级

想办法编写备用方案

步骤一

步骤二

XML
feign:
  sentinel:
    enabled: true # 开启Feign对sentinel的支持

编写Factory

java
package cn.itcast.feign.clients.fallback;

import cn.itcast.feign.clients.UserClient;
import cn.itcast.feign.pojo.User;
import feign.hystrix.FallbackFactory;
import lombok.extern.slf4j.Slf4j;


@Slf4j
public class UserClientFallBackFactory implements FallbackFactory<UserClient> {
    @Override
    public UserClient create(Throwable throwable) {
        return new UserClient (){
            @Override
            public User getUserById(Long id) {
                log.error("查询日志异常",throwable);
                return new User();
            }
        };
    }
}

添加到Bean管理

java
    @Bean
    public UserClientFallBackFactory userClientFallBackFactory(){
        return new UserClientFallBackFactory();
    }

修改装饰器

java
@FeignClient(value = "userservice",fallbackFactory = UserClientFallBackFactory.class)

隔离方式

两种隔离方式的优缺点

实现线程隔离

超出限制的请求会执行Factory中的方法

console
2025-10-28 22:58:33.338 ERROR 22416 --- [nio-8080-exec-6] c.i.f.c.f.UserClientFallBackFactory      : 查询日志异常

com.alibaba.csp.sentinel.slots.block.flow.FlowException: null

熔断降级

熔断策略-慢调用

熔断策略-异常比例，异常数

8.授权规则

对请求者的身份进行判断

在网关的请求添加请求头判断是否为网关的请求

java
package cn.itcast.order.sentinel;

import com.alibaba.csp.sentinel.adapter.spring.webmvc.callback.RequestOriginParser;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

import javax.servlet.http.HttpServletRequest;


@Component
public class HeaderOriginParser implements RequestOriginParser {
    @Override
    public String parseOrigin(HttpServletRequest request) {
        // 尝试获取请求头
        String origin = request.getHeader("origin");
        if (StringUtils.isEmpty(origin)) {
            return "blank";
        }
        return origin;
    }
}
// 对服务端重写原有的接口

XML
在gateway端添加origin请求头
            - AddRequestHeader=origin,gateway

在sentinel添加规则

阻止除了网关来源的请求访问服务

自定义异常

实现接口

java
package cn.itcast.order.sentinel;

import com.alibaba.csp.sentinel.adapter.spring.webmvc.callback.BlockExceptionHandler;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.alibaba.csp.sentinel.slots.block.authority.AuthorityException;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeException;
import com.alibaba.csp.sentinel.slots.block.flow.FlowException;
import com.alibaba.csp.sentinel.slots.block.flow.param.ParamFlowException;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;




@Component
public class SentinelBlockHandler implements BlockExceptionHandler {
    @Override
    public void handle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, BlockException e) throws Exception {
        String msg = "未知异常";
        int status = 429;
        if (e instanceof FlowException) {
            msg = "请求被限流了";
        }else if (e instanceof DegradeException) {
            msg = "请求被降级了";
        } else if (e instanceof ParamFlowException) {
            msg = "热点参数限流";
        } else if (e instanceof AuthorityException) {
            msg = "请求没有权限";
            status = 401;
        }
        httpServletResponse.setContentType("application/json;charset=utf-8");
        httpServletResponse.setStatus(status);
        httpServletResponse.getWriter().println("{\"message\":\""+msg+"\",\"status\":"+status+"}");

    }
}

规则持久化

解决sentinel在服务重启时配置的规则消失

规则管理模式

规则管理有3种模式

原始模式（不支持持久化）

pull模式

push模式

目录