Feign雪崩处理

在feign声明式调用中，在@FeignClient注解中添加fallback参数

@FeignClient(value = "product-server",fallback = ProductServiceFallback.class)

这个ProductServiceFallback类是ProductService接口的实现类，要作为组件注入

如果需要有服务的异常信息，那么@FeignClient注解中使用fallbackFactory参数

@FeignClient(value = "product-server",fallbackFactory = ProductServiceFallbackFactory.class)

测试feign雪崩时候，productService的服务停了就能测试雪崩了

fallback兜底的两种类

实现​​ProductService​​接口

package com.qiangqiang.fallback;

import com.qiangqiang.entity.Product;
import com.qiangqiang.service.ProductService;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;
@Component
public class ProductServiceFallback implements ProductService {
    @Override
    public List<Product> getProduct() {
        Product product1 = new Product(1, "手机兜底兜底",1);
        Product product2 = new Product(2, "电脑兜底兜底",1);
        List<Product> list = new ArrayList<>();
        list.add(product1);
        list.add(product2);
        return list;
    }

    @Override
    public List<Product> getProductById(Integer id) {
        Product product = new Product(id, "手机兜底"+id,1);
        List<Product> list = new ArrayList<>();
        list.add(product);
        return list;
    }
}

实现​​FallbackFactory<ProductService>​​接口

package com.qiangqiang.fallback;

import com.qiangqiang.entity.Product;
import com.qiangqiang.service.ProductService;
import feign.hystrix.FallbackFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;

@Component
public class ProductServiceFallbackFactory implements FallbackFactory<ProductService> {
    @Override
    public ProductService create(Throwable throwable) {
        Logger logger = LoggerFactory.getLogger(ProductServiceFallbackFactory.class);
        return new ProductService() {
            @Override
            public List<Product> getProduct() {
                logger.error("product-server服务的getProduct方法异常，异常信息为：" + throwable);
                Product product1 = new Product(1, "手机兜底兜底",1);
                Product product2 = new Product(2, "电脑兜底兜底",1);
                List<Product> list = new ArrayList<>();
                list.add(product1);
                list.add(product2);
                return list;
            }

            @Override
            public List<Product> getProductById(Integer id) {
                logger.error("product-server服务的getProductById方法异常，异常信息为：" + throwable);
                Product product = new Product(id, "手机兜底"+id,1);
                List<Product> list = new ArrayList<>();
                list.add(product);
                return list;
            }
        };
    }
}

启动类开启feign注解

package com.qiangqiang;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
public class SpringCloudOrderServerFeignApplication {

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

}

yml配置要额外增加feign对于hystrix的支持

server:
  port: 8005
  tomcat:
    max-threads: 11     #降低最大线程数方便模拟高并发
eureka:
  client:
    service-url:
      defaultZone: http://root:root@eureka2:8762/eureka/,http://root:root@eureka1:8761/eureka/
    register-with-eureka: true     #不注册到注册中心
  instance:
    instance-id: ${spring.cloud.client.ip-address}:${server.port}   #显示ip：port
    prefer-ip-address: true
    lease-renewal-interval-in-seconds: 5    #心跳间隔
    lease-expiration-duration-in-seconds: 15
spring:
  application:
    name: order-server
product-server:
  ribbon:
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule
ribbon:
  ConnecTimeout: 5000
  ReadTimeout: 5000
#额外开启feign对hystrix的支持
feign:
  hystrix:
    enabled: true

依赖项

<dependencies>




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

        <!--注册到注册中心的服务就用client-->
        <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>

        <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.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.0</version>
        </dependency>

    </dependencies>