Cloud Hystrix

Spring Cloud Hystrix 可以实现的功能

    降级，熔断...

0. 工程中引入jar包

　　

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>

1.启动类添加引用

　　@EnableCircuitBreaker 

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients("com.lvlvstart.spring.demo.common.client")
@EnableCircuitBreaker //熔断器注解
public class SpringUserApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringUserApplication.class, args);
    }

}

1.降级

　方法上添加注解 @HystrixCommand ，除了 HystrixBadRequestException 以外的异常，都会触发降级

 @DefaultProperties(defaultFallback = "defaultMsg") : 调用统一处理方法 defaultMsg

 @HystrixCommand 需要降级的方法加

import com.lvlvstart.spring.demo.common.client.SchoolClient;
import com.lvlvstart.spring.demo.common.enums.MsgEnum;
import com.lvlvstart.spring.demo.common.msg.BaseWeb;
import com.lvlvstart.spring.demo.common.msg.Result;
import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @description 类描述
 * @create 2019/12/12 13:57
 */
@RestController
@RequestMapping("rest_feign")
@DefaultProperties(defaultFallback = "defaultMsg")
public class OpenFeignExampleWeb extends BaseWeb {

    @Autowired
    private SchoolClient schoolClient;

    @PostMapping("findAllSchool")
    public Result findAll(){
        return schoolClient.findAll();
    }

    @HystrixCommand
    @PostMapping("findAllSchoolGet")
    public Result findAllGet(){
        return schoolClient.findAll();
    }


    public Result defaultMsg(){
        return fail(MsgEnum.DOWNGRADE.getCode(),MsgEnum.DOWNGRADE.getMsg());
    }
}

　　

2.熔断配置

　

熔断主要的注解中的配置：

　　@HystrixCommand(fallbackMethod = "brekerMsg",commandProperties = {@HystrixProperty(name = "circuitBreaker.enabled",value = "true"),
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "10"), //设置再滚动时间窗口中的最小请求数,
            @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds",value = "10000"),//熔断开启后的时间
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage",value = "50")}) //设置比60%，如果再滚动时间窗口内，大于60%的时候，就会进行熔断
    public Result findAllBreaker(){
        return schoolClient.findAll();
    }

设置失败调用方法：

    public Result brekerMsg(){
        return  fail(MsgEnum.BREAKER.getCode(),MsgEnum.BREAKER.getMsg());
    }

配置方式注入属性（方法上还是要有 @HystrixCommand 注解，但是可以不加任何属性）

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 1000
      circuitBreaker:
        enable: true
        requestVolumeThreshold: 10
        sleepWindowInMilliseconds: 10000
        errorThresholdPercentage: 50
    findAllGet:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 10000
    findAllBreaker:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 1000
      circuitBreaker:
        enable: true
        requestVolumeThreshold: 10
        sleepWindowInMilliseconds: 10000
        errorThresholdPercentage: 50

   

Hystrix Dashboard

　　开启Hystrix面板能够统计调用失败的情况

　　1.引用pom

        <!--dashboard 界面-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </dependency>

　　2.开启注解@EnableHystrixDashboard

　　

import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients("com.lvlvstart.spring.demo.common.client")
@EnableHystrix
@EnableHystrixDashboard
@EnableCircuitBreaker //熔断器注解
public class SpringUserApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringUserApplication.class, args);
    }

　　//改变访问地址
    @Bean
    public ServletRegistrationBean getServlet() {
        HystrixMetricsStreamServlet streamServlet = new HystrixMetricsStreamServlet();
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(streamServlet);
        registrationBean.setLoadOnStartup(1);
        registrationBean.addUrlMappings("/hystrix.stream");
        registrationBean.setName("HystrixMetricsStreamServlet");
        return registrationBean;
    }

}

控制面板地址 localhost:8080 按照如下配置

访问带@HystrixCommand注解的方法，界面就会显示统计数值