SpringCloud之服务降级

整体资源快不够了，忍痛将某些服务先关掉，待渡过难关，再开启回来；

服务降级处理是在客户端实现完成的，与服务端没有关系。

1、接口DeptClientService：

/**
 * 
 * @Description: 修改microservicecloud-api工程，根据已经有的DeptClientService接口

新建

一个实现了FallbackFactory接口的类DeptClientServiceFallbackFactory
 */
//@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);
}

2、编写：DeptClientServiceFallbackFactory

import java.util.List;

import org.springframework.stereotype.Component;

import com.atguigu.springcloud.entities.Dept;

import feign.hystrix.FallbackFactory;

@Component // 不要忘记添加，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)
			{
				return new Dept().setDeptno(id).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")
						.setDb_source("no this database in MySQL");
			}

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

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

3、此时服务提供者provider已经down了，但是我们做了服务降级的处理，让客户端在服务端不可用时，也会获得提示信息，而不会挂起耗死服务器。