Spring Cloud Alibaba之限流与防护组件Sentinel

实例演示1：通过Sentinel实现限流

创建SentinelDemo的Maven项目，配置pom文件：

 <dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency>
</dependencies>

编写启动类：

package prj;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class SpringBootApp {public static void main(String[] args) {SpringApplication.run(SpringBootApp.class, args);}
}

编写application.properties配置文件：

spring.application.name=SentinelDemo
# 与Sentinel控制台交互的端口
spring.cloud.sentinel.transport.port=9000
# sentinel控制台的工作地址和端口
spring.cloud.sentinel.transport.dashboard=localhost:8090

编写Controller控制类ContrllerForLimit：

@RestController
public class ControllerForLimit {@RequestMapping("/sayHello")@SentinelResource(value = "sayHello")public String sayHello() {return "Hello Sentinel";}@RequestMapping("/useSentinel")@SentinelResource(value = "useSentinel")public String useSentinel() {return "Use Sentinel";}}

控制台设置限流参数，运行项目观察效果

实例演示2：实现热点限流效果

在SentinelDemo项目的基础上，新增控制类ContrllerForHotPot：

@RestController
public class ControllerForHotSpot {@RequestMapping("/buyItem")@SentinelResource(value = "buyItem")public String buyItem(@RequestParam(value = "item", required = false) String item,@RequestParam(value = "price", required = false) String price) {return "Hot Spot Demo";}
}

控制台设置热点限流参数，观察效果

实例演示3：实现熔断限流效果

在SentinelDemo项目的基础上，新增控制类ContrllerForFusing：

@RestController
public class ControllerForFusing {@RequestMapping("/testFusing")@SentinelResource(value = "testFusing")public String testFusing() {try {Thread.sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}return "Test Fusing";}
}

控制台设置慢调用比例参数后，编写测试类，运行项目观察熔断效果：

class RequestThread extends Thread{public void run() {RestTemplate restTemplate = new RestTemplate();ResponseEntity<String> entity = restTemplate.getForEntity("http://localhost:8080/testFusing", String.class);System.out.println(entity.getBody());}
}
public class TestFusing {public static void main(String[] args){for(int i = 0;i<1000;i++) {new RequestThread().start();}}
}

实例演示4：实现服务降级效果

在控制类ContrllerForLimit，添加limitForHandle的服务方法

@RestController
public class ControllerForLimit {@RequestMapping("/sayHello")@SentinelResource(value = "sayHello")public String sayHello() {return "Hello Sentinel";}@RequestMapping("/useSentinel")@SentinelResource(value = "useSentinel")public String useSentinel() {return "Use Sentinel";}@RequestMapping("/limitForHandler")@SentinelResource(value = "limitForHandler",fallback ="handleException")public String limitForHandler() {return "limitForHandler";}public String handleException() {return "handler limit Exception";}
}