限流中间件介绍-sentinel-阿里开源限流中间件

一、前言：

      demo框架：SpringBoot+Sentinel

二、demo:

  pom.xml

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.jason.flow.contorl</groupId>
    <artifactId>flowcontrol-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>flowcontrol-demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.3.1.BUILD-SNAPSHOT</spring-boot.version>
        <spring-cloud-alibaba.version>2.2.2.RELEASE</spring-cloud-alibaba.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-alibaba-sentinel-datasource</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-reactor-adapter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>18.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>${spring-cloud-alibaba.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.3.1.BUILD-SNAPSHOT</version>
                <configuration>
                    <mainClass>com.jason.flow.contorl.flowcontroldemo.FlowcontrolDemoApplication</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
        <repository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </pluginRepository>
        <pluginRepository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>

</project>
           

  Java代码：

@SentinelResource(value="doTest" , fallback="fallback",blockHandler = "blockHandler")      

  doTest表示需要保护的方法，blockHandler 和 fallback同时存在，只会使用blockHandler配置的限流方法。

  注意点：

1）doTest  需要与限流方法名称，以及配置的限流规则(FlowRule.setResource("doTest"))保持一致。

2）限流方法blockHandler   方法的返回值类型和方法参数类型需要与被保护的方法一致，同时方法参数需要额外增加BlockException参数。

package com.jason.flow.contorl.flowcontroldemo.service;
import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import org.springframework.stereotype.Service;
/**
 * @program: flowcontrol-demo
 * @description
 * @author: 大龄程序猿
 * @create: 2020-09-21 23:03
 **/
@Service
public class TestService {

    @SentinelResource(value="doTest" , fallback="fallback",blockHandler = "blockHandler")
    public String doTest(String name)
    {
        return "hello"+name;
    }

    public String  blockHandler(String name, BlockException  e)
    {
        return  "被限流";
    }

    public String fallback(String name)
    {
        return "被降级了";
    }
}
           

 control层代码：

import com.jason.flow.contorl.flowcontroldemo.service.TestService;
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.RestController;

/**
 * @program: flowcontrol-demo
 * @description
 * @author: 大龄程序猿
 * @create: 2020-09-21 23:13
 **/
@RestController
public class TestControl {

    @Autowired
    TestService  testService;

    @GetMapping("/hello/{name}")
    public String sayHello(@PathVariable String name)
    {
        return testService.doTest(name);
    }
}