前言：作者查阅了Sentinel官网、51CTO、CSDN、码农家园、博客园等很多技术文章都没有很准确的springmvc集成Sentinel的示例，因此整理了本文，主要介绍SpringMvc集成Sentinel

SpringMvc集成Sentinel

一、Sentinel 介绍

随着微服务的流行，服务和服务之间的稳定性变得越来越重要。Sentinel 是面向分布式、多语言异构化服务架构的流量治理组件，主要以流量为切入点，从流量路由、流量控制、流量整形、熔断降级、系统自适应过载保护、热点流量防护等多个维度来帮助开发者保障微服务的稳定性。

GitHub主页：https://github.com/alibaba/Sentinel

中文文档：https://sentinelguard.io/zh-cn/docs/introduction.html

控制台文档：https://sentinelguard.io/zh-cn/docs/dashboard.html

核心类解析：https://github.com/alibaba/Sentinel/wiki/Sentinel-%E6%A0%B8%E5%BF%83%E7%B1%BB%E8%A7%A3%E6%9E%90

Sentinel示例项目：https://github.com/alibaba/Sentinel/tree/master/sentinel-demo

https://github.com/alibaba/spring-cloud-alibaba/tree/master/spring-cloud-alibaba-examples/sentinel-example

二、Sentinel 基本概念

资源

资源是 Sentinel 的关键概念。它可以是 Java 应用程序中的任何内容，例如，由应用程序提供的服务，或由应用程序调用的其它应用提供的服务，甚至可以是一段代码。在接下来的文档中，我们都会用资源来描述代码块。

只要通过 Sentinel API 定义的代码，就是资源，能够被 Sentinel 保护起来。大部分情况下，可以使用方法签名，URL，甚至服务名称作为资源名来标示资源。

规则

围绕资源的实时状态设定的规则，可以包括流量控制规则、熔断降级规则以及系统保护规则。所有规则可以动态实时调整。

三、springMVC集成Sentinel

这里用的是spring

<spring.version>5.3.18</spring.version>

<servlet.api.version>2.5</servlet.api.version> <sentinel.version>1.8.6</sentinel.version>

1、springmvc项目引入依赖pom

 <!-- 这是sentinel的核心依赖 --> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-core</artifactId> <version>${sentinel.version}</version> </dependency> <!-- 这是将自己项目和sentinel-dashboard打通的依赖 --> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-transport-simple-http</artifactId> <version>${sentinel.version}</version> </dependency> <!-- 这是使用sentinel对限流资源进行AOP --> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-annotation-aspectj</artifactId> <version>${sentinel.version}</version> </dependency> <!--这是使用sentinel适配Web Servlet的依赖--> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-web-servlet</artifactId> <version>${sentinel.version}</version> </dependency> <!-- 这是使用sentinel热点参数限流功能依赖 --> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-parameter-flow-control</artifactId> <version>${sentinel.version}</version> </dependency>

2、添加配置文件

在application.properties下创建同级文件sentinel.properties，内容如下

# 集成到sentinel的项目名称 project.name=spring-sentinel-demo # 对应的sentinel-dashboard地址 csp.sentinel.dashboard.server=localhost:8080

3、添加配置类引入配置文件

创建配置类SentinelAspectConfiguration并引入配置文件sentinel.properties

import com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.PropertySource; import org.springframework.context.annotation.PropertySources; @Configuration @PropertySources({@PropertySource("classpath:/sentinel.properties")}) public class SentinelAspectConfiguration { @Bean public SentinelResourceAspect sentinelResourceAspect() { return new SentinelResourceAspect(); } }

4、web.xml新增如下过滤器配置

 <filter> <filter-name>SentinelCommonFilter</filter-name> <filter-class>com.alibaba.csp.sentinel.adapter.servlet.CommonFilter</filter-class> </filter> <filter-mapping> <filter-name>SentinelCommonFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>

接入 filter 之后，所有访问的 Web URL 就会被自动统计为 Sentinel 的资源---来源于 https://sentinelguard.io/zh-cn/docs/open-source-framework-integrations.html

开源框架适配的Web 适配下的Web Servlet

5、创建Controller接口

@Controller public class WebMvcTestController { @GetMapping("/hello") @ResponseBody public String apiHello(String id) { System.out.println("id = " + id); Date date = new Date(); System.out.println("date = " + date); return "Hello!"; } @GetMapping("/doBusiness") @ResponseBody public String doBusiness(String id) { System.out.println("doBusiness = "); return "Oops..."; } }

6、下载控制台-即图形化实时监控平台

参考 https://sentinelguard.io/zh-cn/docs/dashboard.html Sentinel 控制台的下载和启动

访问 https://github.com/alibaba/Sentinel/releases/tag/1.8.6



点击下载

7、运行控制台

java -Dserver.port=8080 -Dcsp.sentinel.dashboard.server=localhost:8080 -Dproject.name=sentinel-dashboard -jar sentinel-dashboard.jar

运行控制台后运行springmvc项目，然后访问某一个路径，就可以在控制台看到了，实时监控如果这个路径没有被访问是显示不出来的



这个时候我们配置限流为即Qps为2



8、测试限流

这里我们用postman进行压测，填写请求的路径保存。并点击run调出压测执行器



执行后查看结果如下



四、自定义异常返回

1、定义如下接口(这里只进行了常见的url定义方式的定义)

import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.*; @Controller @RequestMapping("/test") public class WebMvcTestController { /** * 1.未配置流控规则 1000次请求没有间隔发起请求，应该在1秒中完成09:44:33 * @param id * @return */ @RequestMapping("/RequestMapping") @ResponseBody public String RequestMapping(String id) { return "RequestMapping!"; } @GetMapping("/GetMapping") @ResponseBody public String GetMapping(String id) { return "GetMapping..."; } @PostMapping("/PostMapping") @ResponseBody public String PostMapping(String id) { return "PostMapping..."; } /* * 路径变量（Path Variables）：使用花括号 {} 来标记路径中的变量，并通过 @PathVariable 注解将其绑定到方法参数上 * */ @GetMapping("/GetMapping/{id}") @ResponseBody public String apiFoo(@PathVariable("id") Long id) { return "Hello " + id; } /* * Ant风格的路径匹配： * 使用 ? 表示任意单个字符， * * 表示任意多个字符（不包含路径分隔符 /）， * ** 表示任意多个字符（包含路径分隔符 /）。 * */ @GetMapping("/Ant/*/{id}") @ResponseBody public String Ant(@PathVariable("id") Long id) { return "Ant " + id; } /* * 正则表达式路径匹配：使用 @RequestMapping 注解的 value 属性结合正则表达式来定义请求路径。 * */ @GetMapping(value = "/users/{id:\\d+}") @ResponseBody public String pattern(@PathVariable("id") int id) { return "Ant " + id; } } 

2、自定义限流返回处理Handler

import com.alibaba.csp.sentinel.adapter.servlet.callback.UrlBlockHandler; 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 com.alibaba.csp.sentinel.slots.system.SystemBlockException; import com.alibaba.fastjson.JSON; import org.springframework.context.ApplicationContext; import org.springframework.web.method.HandlerMethod; import org.springframework.web.servlet.mvc.condition.PatternsRequestCondition; import org.springframework.web.servlet.mvc.method.RequestMappingInfo; import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping; import org.springframework.web.util.UrlPathHelper; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.util.*; public class SentinelExceptionHandler implements UrlBlockHandler { @Override public void blocked(HttpServletRequest request, HttpServletResponse httpServletResponse, BlockException e) throws IOException { String contextPath = request.getContextPath(); String servletPath = request.getServletPath(); String requestURI = request.getRequestURI(); String url = request.getRequestURL().toString(); System.out.println("servletPath = " + servletPath); System.out.println("requestURI = " + requestURI); System.out.println("url = " + url); if (contextPath == null) { contextPath = ""; } ApplicationContext controllerApplicationContext = LiteFlowApplicationContext.getControllerApplicationContext(); RequestMappingHandlerMapping handlerMapping = controllerApplicationContext.getBean(RequestMappingHandlerMapping.class); // 查找匹配的处理方法 Class<?> returnType = null; Map<RequestMappingInfo, HandlerMethod> handlerMethods = handlerMapping.getHandlerMethods(); for (Map.Entry<RequestMappingInfo, HandlerMethod> entry : handlerMethods.entrySet()) { RequestMappingInfo requestMappingInfo = entry.getKey(); HandlerMethod handlerMethod = entry.getValue(); //匹配url if (requestMappingInfo.getPatternsCondition().getPatterns().contains(requestURI)) { System.out.println("Controller: " + handlerMethod.getBeanType().getName()); System.out.println("Method: " + handlerMethod.getMethod().getName()); System.out.println("getReturnType: " + handlerMethod.getMethod().getReturnType()); returnType = handlerMethod.getMethod().getReturnType(); break; } //匹配路径带参数的url UrlPathHelper pathHelper = new UrlPathHelper(); String lookupPath = pathHelper.getPathWithinApplication(request); PatternsRequestCondition patternsCondition = requestMappingInfo.getPatternsCondition(); if (patternsCondition != null && patternsCondition.getMatchingPatterns(lookupPath).size() > 0) { System.out.println("Controller1111: " + handlerMethod.getBeanType().getName()); System.out.println("Method111: " + handlerMethod.getMethod().getName()); System.out.println("getReturnType: " + handlerMethod.getMethod().getReturnType()); returnType = handlerMethod.getMethod().getReturnType(); break; } } httpServletResponse.setContentType("application/json;charset=utf-8"); ResponseData data = null; if (returnType != null) { if (returnType == String.class) { String str = "返回类型为字符串方法限流"; httpServletResponse.getWriter().write(str); return; } else if (returnType == Integer.class) { httpServletResponse.getWriter().write(new Integer(1)); return; } else if (returnType == Long.class) { httpServletResponse.getWriter().write(2); return; } else if (returnType == Double.class) { } else if (returnType == Boolean.class) { } else if (returnType == Float.class) { } else if (returnType == Byte.class) { } } //BlockException 异常接口,包含Sentinel的五个异常 // FlowException 限流异常 // DegradeException 降级异常 // ParamFlowException 参数限流异常 // AuthorityException 授权异常 // SystemBlockException 系统负载异常 if (e instanceof FlowException) { data = new ResponseData(-1, "流控规则被触发......"); } else if (e instanceof DegradeException) { data = new ResponseData(-2, "降级规则被触发..."); } else if (e instanceof AuthorityException) { data = new ResponseData(-3, "授权规则被触发..."); } else if (e instanceof ParamFlowException) { data = new ResponseData(-4, "热点规则被触发..."); } else if (e instanceof SystemBlockException) { data = new ResponseData(-5, "系统规则被触发..."); } httpServletResponse.getWriter().write(JSON.toJSONString(data)); } }

3、使用自定义限流处理类

import com.alibaba.csp.sentinel.adapter.servlet.callback.WebCallbackManager; import org.springframework.context.annotation.Configuration; @Configuration public class SentinelConfig { public SentinelConfig() { WebCallbackManager.setUrlBlockHandler(new SentinelExceptionHandler()); } }

4、配置限流并测试结果

当开启限流后访问触发自定义UrlBlockHandler后结果如下

访问对应得url后控制台打印

servletPath = /test/RequestMapping requestURI = /test/RequestMapping url = http://localhost:8081/test/RequestMapping Controller: org.example.WebMvcTestController Method: RequestMapping getReturnType: class java.lang.String servletPath = /test/GetMapping requestURI = /test/GetMapping url = http://localhost:8081/test/GetMapping Controller: org.example.WebMvcTestController Method: GetMapping getReturnType: class java.lang.String servletPath = /test/PostMapping requestURI = /test/PostMapping url = http://localhost:8081/test/PostMapping Controller: org.example.WebMvcTestController Method: PostMapping getReturnType: class java.lang.String servletPath = /test/GetMapping/4 requestURI = /test/GetMapping/4 url = http://localhost:8081/test/GetMapping/4 Controller1111: org.example.WebMvcTestController Method111: apiFoo getReturnType: class java.lang.String servletPath = /test/Ant/a/5 requestURI = /test/Ant/a/5 url = http://localhost:8081/test/Ant/a/5 Controller1111: org.example.WebMvcTestController Method111: Ant getReturnType: class java.lang.String servletPath = /test/users/5 requestURI = /test/users/5 url = http://localhost:8081/test/users/5 Controller1111: org.example.WebMvcTestController Method111: pattern getReturnType: class java.lang.String

5、页面效果如下

五、springboot集成Sentinel

因为springboot集成文章较多，这里不多做赘述

Sentinel 与 Spring Boot/Spring Cloud 的整合见 Sentinel Spring Cloud Starter。

作者：京东健康 马仁喜

来源：京东云开发者社区 转载请注明来源