<Spring Cloud>入门五 hystrix

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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;

    }