##方法一：设置fallback属性

Feign Hystrix Fallbacks 官网解释 Hystrix supports the notion of a fallback: a default code path that is executed when they circuit is open or there is an error. To enable fallbacks for a given @FeignClient set the fallback attribute to the class name that implements the fallback.

它说你想要给Feign fallback功能，就给@FeignClient注解设置fallback属性，并且回退类要继承@FeignClient所注解的接口

• 官方实例：

@FeignClient(name = "hello", fallback = HystrixClientFallback.class)protected interface HystrixClient {    @RequestMapping(method = RequestMethod.GET, value = "/hello")    Hello iFailSometimes();}static class HystrixClientFallback implements HystrixClient {    @Override    public Hello iFailSometimes() {        return new Hello("fallback");    }}复制代码

• 但是如果HystrixClientFallback类拿出去单独作为一个类的话，我们就得在该类上添加注解@Component

• 最后访问feign端口7901调用的服务

  访问/health
  访问正常。

• 然后我关闭user服务再进行访问

• To disable Hystrix support for Feign, set feign.hystrix.enabled=false. 想关闭feign对hystrix的支持的话，在application里配置feign.hystrix.enabled=false.

To disable Hystrix support on a per-client basis create a vanilla Feign.Builder with the "prototype" scope, e.g.: 想要以每个Feign客户端为基础来禁用或开启Hystrix 请在需要禁用的类中添加

@Bean	@Scope("prototype")	public Feign.Builder feignBuilder() {		return Feign.builder();	}复制代码

原理：官网上有 Feign.Builder feignBuilder: HystrixFeign.Builder 说明了 Feign 默认是开启HystrixFeign的，默认Builder对象是HystrixFeign，我们在这里只Builder Feign，所以会达到禁用Hystrix的效果 ##方法二：设置fallfactory属性 **提示：**如果fallback默认优先级比fallfactory优先级高。所以二者都存在的话，会访问fallback的回退方法。 这里不做演示。 那么fallback和fallfactory有什么区别呢

不多哔哔，先看代码后加分析。

@FeignClient(name = "hello", fallbackFactory = HystrixClientFallbackFactory.class)protected interface HystrixClient {	@RequestMapping(method = RequestMethod.GET, value = "/hello")	Hello iFailSometimes();}@Componentstatic class HystrixClientFallbackFactory implements FallbackFactory
    
      {	@Override	public HystrixClient create(Throwable cause) {		return new HystrixClientWithFallBackFactory() {			@Override			public Hello iFailSometimes() {				return new Hello("fallback; reason was: " + cause.getMessage());			}		};	}}复制代码
    

这是官网给的demo。我在这里把类都提了出来。 UserFeignClient 接口：

package com.fantj.moviefeign.feign;import com.fantj.fantjconsumermovie.entity.User;import feign.hystrix.FallbackFactory;import org.springframework.cloud.netflix.feign.FeignClient;import org.springframework.web.bind.annotation.*;/** * Created by Fant.J. * 2017/12/1 19:33 */@FeignClient(value = "provider-user3",fallbackFactory = HystrixFallbackFactory.class)public interface UserFeignClient {    @RequestMapping(value = "/simple/{id}",method = RequestMethod.GET)    User findById(@PathVariable("id") Long id);}复制代码

HystrixFallbackFactory 实现FallbackFactory接口

package com.fantj.moviefeign.feign;import com.fantj.fantjconsumermovie.entity.User;import feign.hystrix.FallbackFactory;import lombok.extern.slf4j.Slf4j;import org.springframework.stereotype.Component;/** * Created by Fant.J. * 2017/12/3 14:04 */@Component@Slf4jpublic class HystrixFallbackFactory implements FallbackFactory
    
     {    @Override    public UserFeignClient create(Throwable throwable) {        log.info("fallback; reason was: " + throwable.getMessage());        return id -> {            User user = new User();            user.setId(0L);            return user;        };    }}复制代码
    

注意我在重写create方法中把id返回值固定为0。如果它返回的id是0，证明fallbackfactory启用。

#####fallback和fallfactory区别：

• fallback只是重写了回退方法。
• fallfactory层面比较深，因为它可以调出底层异常。