<Spring Cloud>入门五 hystrix

1.服务熔断

1.1引入坐标

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

1.2 主启动类标识

package org.maple;

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

/**
 * @author mapleins
 * @Date 2019-01-12 17:13
 * @Desc
 **/
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient//服务发现 可以看到服务信息
@EnableCircuitBreaker //开启断路器
public class App_Provider_Dept_8001_Hystrix {

    public static void main(String[] args) {
        SpringApplication.run(App_Provider_Dept_8001_Hystrix.class,args);
    }
}

1.3 添加熔断方法

    @GetMapping("/dept/get/{id}")
    //出错调用hystrixCommand中的方法
    @HystrixCommand(fallbackMethod = "hystrix_get")
    public Dept get(@PathVariable("id") Long id) {
        Dept dept = service.find(id);
        if (null == dept) {
            throw new RuntimeException("该id"+id+"没有对应信息");
        }
        return dept;
    }

    public Dept hystrix_get(@PathVariable("id") Long id){
        return new Dept().setDeptNo(id).setDName("该id"+id+"没有对应的信息，null--@HystrixCommand").setDb_source("no this database in Mysql");
    }

1.4 访问

2.服务降级

　　添加服务熔断，会造成方法翻倍，每一个接口都需要一个服务熔断，此时就可以使用服务降级，类似异常处理+切面编程

2.1 针对接口编写回调函数工厂，在接口上声明工厂类

　　之前将服务的调用通过feign来实现接口调用，现在对接口操作实现服务降级，对整个方法进行统一管理，实现解耦

package org.maple.service;

import feign.hystrix.FallbackFactory;
import org.maple.entity.Dept;
import org.springframework.stereotype.Component;

import java.util.List;

/**
 * @author mapleins
 * @Date 2019-01-13 12:01
 * @Desc 服务降级
 **/
@Component
public class DeptClientServiceFallbackFactory implements FallbackFactory<DeptClientService> {

    @Override
    public DeptClientService create(Throwable throwable) {

        return new DeptClientService() {
            @Override
            public boolean add(Dept dept) {
                return false;
            }

            @Override
            public Dept get(Long id) {
                return new Dept().setDeptNo(id).setDName("该服务已经关闭").setDb_source("no this database in Mysql");
            }

            @Override
            public List<Dept> list() {
                return null;
            }
        };
    }
}

package org.maple.service;

import org.maple.entity.Dept;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;

import java.util.List;

/**
 * @author mapleins
 * @Date 2019-01-12 23:10
 * @Desc 通过接口和注解 面向接口编程访问微服务
 **/
//@FeignClient("ms-provider-dept")
@FeignClient(value = "ms-provider-dept",fallbackFactory = DeptClientServiceFallbackFactory.class) //服务降级类
public interface DeptClientService {

    @PostMapping("/dept/add")
    boolean add(@RequestBody Dept dept);

    @GetMapping("/dept/get/{id}")
    Dept get(@PathVariable("id") Long id);

    @GetMapping("/dept/list")
    List<Dept> list();

}

2.2 在调用接口的消费方开启hystrix

feign:
  hystrix:
    enabled: true #开启服务降级

2.3 调用

开启2个eureka server,1个provider-dept,1个consumer

关闭provider

3.Hystrix Dashboard 准实时调用监控

3.1 操作

需要监控的服务必须依赖：

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

新建一个hystrix-dashboard工程

<?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">
    <parent>
        <artifactId>spring-cloud-learning</artifactId>
        <groupId>org.org.maple</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>ms-consumer-hystrix-dashboard</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.org.maple</groupId>
            <artifactId>ms-common-api</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </dependency>
    </dependencies>

</project>

server:
  port: 9001

package org.maple;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;

/**
 * @author mapleins
 * @Date 2019-01-13 12:44
 * @Desc
 **/
@SpringBootApplication
@EnableHystrixDashboard //开启仪表盘
public class App_Hystrix_Dashboard_9001 {

    public static void main(String[] args) {
        SpringApplication.run(App_Hystrix_Dashboard_9001.class,args);
    }
}

3.2 启动界面

如果访问路径404，则需要在监控的服务中配置一个Bean

    @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;
    }