Spring Cloud Hystrix熔断器（hello world级）

工程准备：micro-weather-eureka-client-feign-hystrix(调用服务者，熔断器逻辑方),

mas-weather-city-eureka（服务被调用者）

调用服务者：为feign项目改写而来

依赖：

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-openfeign</artifactId>
                <version>2.0.0.RC1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/libs-milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-hystrix -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
            <version>1.4.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

    </dependencies>

启动类配置：

package com.example.microweathereurekaclient;

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;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@EnableCircuitBreaker
public class MicroWeatherEurekaClientApplication {

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

熔断逻辑：

package com.example.microweathereurekaclient.controller;

import com.example.microweathereurekaclient.service.CityClient;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class CityController {
    @Autowired
    private CityClient cityClient;
    @RequestMapping("/cities")
    @HystrixCommand(fallbackMethod = "defaultMethod")  //如果产生熔断，执行defaultMehthod方法
    public String listCity(){
        //通过Feign客户端来查找
        String body=cityClient.listCity();
        return body;
    }
    public String defaultMethod(){
        return "熔断器启用";
    }
}

两个工程启动：正常调用：

关闭被调用工程（异常）:

还有将熔断后的处理方法写到新的类中的方式，暂时没有继续写了。