SpringCloud 服务降级

业务说明：假设银行有3个窗口A,B,C，每个窗口提供不同的业务，现在A窗口的服务人员，人手不够急需从C或者B窗口调人处理业务，C或者B窗口挂起暂停服务的牌子

步骤一：修改SpringCloud -api工程，创建一个新的类实现FallBackFactory接口

package com.gcxzflgl.springCloud.service;

import java.util.List;

import org.springframework.stereotype.Component;

import com.gcxzflgl.springCloud.entity.Dept;

import feign.hystrix.FallbackFactory;

@Component // 不要忘记添加
public class DeptClientServiceFallbackFactory implements FallbackFactory<DeptClientService>
{
	@Override
	public DeptClientService create(Throwable throwable)
	{
		return new DeptClientService() {
			@Override
			public Dept get(long id)
			{
				Dept dept = new Dept();
				dept.setDeptno(id);
				dept.setDname("该ID：" + id + "没有没有对应的信息,Consumer客户端提供的降级信息,此刻服务Provider已经关闭");
				dept.setDb_source("no this database in MySQL");
				return dept;
			}

			@Override
			public List<Dept> list()
			{
				return null;
			}

			@Override
			public boolean add(Dept dept)
			{
				return false;
			}
		};
	}
}

package com.gcxzflgl.springCloud.service;

import java.util.List;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.gcxzflgl.springCloud.entity.Dept;


//@FeignClient(value = "MICROSERVICECLOUD-DEPT")
@FeignClient(value = "MICROSERVICECLOUD-DEPT",fallbackFactory=DeptClientServiceFallbackFactory.class)
public interface DeptClientService
{
	@RequestMapping(value = "/dept/get/{id}", method = RequestMethod.GET)
	public Dept get(@PathVariable("id") long id);

	@RequestMapping(value = "/dept/list", method = RequestMethod.GET)
	public List<Dept> list();

	@RequestMapping(value = "/dept/add", method = RequestMethod.POST)
	public boolean add(Dept dept);
}

这两个类说明，如果发生任何异常，进入全局断路器里根据错误返回不同的提示

然后，mvn clean->mvn install 打包成jar，供其他模块调用

步骤二：修改feign工程applcation.yml，添加如下

feign: 
  hystrix: 
    enabled: true

步骤三：启动7001，7002，7003三个Eureka,启动provider-dept-8001,再启动feign，正常访问localhost/consumer/dept/get/1能正常返回数据，如果现在关闭8001端口也就是C或者B窗口提示如下：

此时服务已经down掉，但做了降级处理，让客户端在服务端不可用时也会获得提示信息而不会挂起服务器！

SpringCloud 服务降级

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