SpringCloud: sentinel在具体服务上限流（RestTemplate)

1.下载sentinel dashboard并启动

java -Dserver.port=9999 -Dcsp.sentinel.dashboard.server=localhost:9999 -Dproject.name=sentinel-dashboard -jar sentinel-dashboard-1.7.0.jar

2.在application.properties中增加sentinel和Eureka相关的配置

server.port=8813
spring.application.name=xiaozhang
eureka.client.serviceUrl.defaultZone=http://139.198.xx.xx:8761/eureka/,http://81.70.xx.xx:8761/eureka/
management.endpoints.web.exposure.include=*
spring.cloud.loadbalancer.ribbon.enabled=false
spring.cloud.sentinel.transport.dashboard=localhost:9999
feign.sentinel.enabled=true
resttemplate.sentinel.enabled=true

3.在pom.xml中增加相关依赖

<?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">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>cn.edu.tju</groupId>
    <artifactId>springcloudsentinelflowcontroll2</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.SR1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>



            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.0.0.RELEASE</version>
                <type>pom</type>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba.cloud/spring-cloud-starter-alibaba-sentinel -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>2.0.4.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            <version>2.0.4.RELEASE</version>

        </dependency>


        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

4.在启动类上加上注解
@EnableEurekaClient
5.编写RestTemplate配置类及限流类

package cn.edu.tju.config;

import com.alibaba.cloud.sentinel.annotation.SentinelRestTemplate;
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 MyConfig {
    @Bean
    @LoadBalanced
    @SentinelRestTemplate(fallback = "handleException", fallbackClass = ExceptionUtil.class, blockHandler="handleBlock",blockHandlerClass=ExceptionUtil.class)
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

}

package cn.edu.tju.config;

import com.alibaba.cloud.sentinel.rest.SentinelClientHttpResponse;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import org.springframework.http.HttpRequest;
import org.springframework.http.client.ClientHttpRequestExecution;

public class ExceptionUtil {
    public static SentinelClientHttpResponse handleException(HttpRequest request,
                                                             byte[] body, ClientHttpRequestExecution execution, BlockException ex) {
        System.err.println("Exception: " + ex.getClass().getCanonicalName());
        return new SentinelClientHttpResponse("异常发生了");
    }

    public static SentinelClientHttpResponse handleBlock(HttpRequest request,
                                                      byte[] body, ClientHttpRequestExecution execution, BlockException ex) {
        System.err.println("flow limitation: " + ex.getClass().getCanonicalName());
        return new SentinelClientHttpResponse("限流发生了");
    }
}

6.编写controller类

package cn.edu.tju.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class RestTemplateController {
    @Autowired
    private RestTemplate restTemplate;
    @RequestMapping("/rest")
    public String rest(){
        String result=restTemplate.getForObject("http://demoservice/test", String.class);

        return result;
    }

}

7.在sentinel控制台页面(http://localhost:9999,用户名密码sentinel)增加流控规则，主要是要配置资源名（请求类型加冒号加Feign请求的地址）和阈值

8.启动应用，快速访问控制器类中的接口地址（可快速点击刷新按钮）,可以看到限流类中的方法被调用了