Spring Cloud Hystrix熔断器的使用（服务降级）

在消费者中加入依赖

        <!--熔断器-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
            <version>2.1.5.RELEASE</version>
        </dependency>

在启动类中加入注解@EnableCircuitBreaker和@EnableHystrix

 所以改变后的启动类在继上一篇博客后的代码如下：

package com.gaolang;


import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;



@SpringBootApplication
@EnableCircuitBreaker
@EnableFeignClients
@EnableHystrix
public class OrderMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderMain80.class,args);
    }

    @LoadBalanced // 使 RestTemplate 自动支持 Ribbon 负载均衡
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

而controller层的代码使用熔断器后因如下：

    @Autowired
    private OrderFeignClient orderFeignClient; // 注入 Feign 客户端

    @PostMapping(value = "/customer/payment/create")
    public CommonResult<Payment>  create(Payment payment){
        return orderFeignClient.create(payment);
    }

    @HystrixCommand(fallbackMethod = "listByHystirx",commandProperties = {
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "5"), //请求次数
    }) //如果请求次数达到5次都是失败，那么直接调用listByHystirx
    @GetMapping(value = "/customer/payment/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id){
        CommonResult result  = orderFeignClient.getPaymentById(id);
        System.out.println("result: " + result);
        return result;
    }

    // 修改后的回退方法
    public CommonResult<Payment> listByHystirx(Long id) {
        return new CommonResult<>(444, "服务端已停止服务", null);
    }

因为这是单个api接口的回退方法所以

• 回退方法 listByHystirx 的参数类型必须与 getPaymentById 方法完全一致，即 Long id。
• 回退方法的返回类型也必须与 getPaymentById 保持一致，即 CommonResult<Payment>