Feign与Hystrix服务熔断服务降级解耦

1. Feign与Hystrix服务熔断服务降级解耦

用@HystrixCommand fallbackMethod是很不好的，因为和业务代码耦合度太高，不利于维护，所以需要解耦。

1.1) 项目microservice-student-provider-hystrix-1004的StudentService.java增加getInfo()方法

public Map<String,Object> getInfo();

1.2) 项目microservice-student-provider-hystrix-1004的StudentServiceImpl.java增加getInfo()方法

@Override
public Map<String, Object> getInfo() {
    Map<String,Object> map=new HashMap<String,Object>();
    map.put("code", 200);
    map.put("info", "业务数据xxxxx");
    return map;
}

1.3) 项目microservice-student-provider-hystrix-1004的StudentController.java增加getInfo()方法，注释之前的getInfo()和getInfoFallback()方法

@ResponseBody
@GetMapping(value="/getInfo")
public Map<String,Object> getInfo() throws InterruptedException{
    Thread.sleep(900);
    return studentService.getInfo();
}

1.4) 项目microservice-student-provider-hystrix-1005重复以上三步

1.5) 公共模块项目microservice-common的StudentClientService接口，新增getInfo方法

@GetMapping(value="/student/getInfo")
public Map<String,Object> getInfo();

1.6) 公共模块项目microservice-common新建StudentClientFallbackFactory类，实现FallbackFactory<StudentClientService>接口

package com.andrew.service;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.springframework.stereotype.Component;
import com.andrew.entity.Student;
import feign.hystrix.FallbackFactory;

@Component
public class StudentClientFallbackFactory implements FallbackFactory<StudentClientService> {
    @Override
    public StudentClientService create(Throwable cause) {
        return new StudentClientService() {
            @Override
            public boolean save(Student student) {
                return false;
            }
            @Override
            public List<Student> list() {
                return null;
            }
            @Override
            public Map<String, Object> getInfo() {
                Map<String, Object> map = new HashMap<String, Object>();
                map.put("code", 500);
                map.put("info", "系统出错，稍后重试");
                return map;
            }
            @Override
            public Student get(Integer id) {
                return null;
            }
            @Override
            public boolean delete(Integer id) {
                return false;
            }
        };
    }
}

1.7) 公共模块项目microservice-common的StudentClientService接口的@FeignClient注解加下fallbackFactory属性

@FeignClient(value="MICROSERVICE-STUDENT",fallbackFactory=StudentClientFallbackFactory.class)

1.8) 项目microservice-student-consumer-feign-80修改StudentConsumerFeignController.java新增方法调用，支持Hystrix

@GetMapping(value="/getInfo")
@ResponseBody
public Map<String,Object> getInfo(){
    return studentClientService.getInfo();
}

1.9) 项目microservice-student-consumer-feign-80的application.yml加上hystrix支持

feign: 
  hystrix: 
    enabled: true

microservice-student-provider-hystrix-1004
Thread.sleep(900); 业务数据xxxxx1004
microservice-student-provider-hystrix-1005
Thread.sleep(2000); 业务数据xxxxx1005

启动microservice-eureka-server-2001
启动microservice-eureka-server-2002
启动microservice-eureka-server-2003
启动microservice-student-provider-hystrix-1004
启动microservice-student-provider-hystrix-1005
启动microservice-student-consumer-feign-80

http://localhost/student/getInfo
随机出现
{"code":500,"info":"系统出错，稍后重试"}
{"code":200,"info":"业务数据xxxxx1004"}

2. Feign Hystrix整合之超时时间配置

Feign Hystrix整合后，hystrix超时时间配置的话要配置到消费端。

2.1) 项目microservice-student-consumer-feign-80的application.yml里增加配置

ribbon: 
  ReadTimeout: 10000
  ConnectTimeout: 9000
hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 3000

如果没有ribbon超时时间设置，就会无效。因为还有一个feign也有一个超时时间的设置，当然feign底层是ribbon的封装，所以 直接配置ribbon，ribbon默认超时也是1秒。
这里都是强制要求，ribbon的超时时间要大于hystrix的超时时间，否则 hystrix自定义的超时时间毫无意义。

microservice-student-provider-hystrix-1004
Thread.sleep(1500); 
业务数据xxxxx1004
microservice-student-provider-hystrix-1005
Thread.sleep(2000); 
业务数据xxxxx1005

启动microservice-eureka-server-2001
启动microservice-eureka-server-2002
启动microservice-eureka-server-2003
启动microservice-student-provider-hystrix-1004
启动microservice-student-provider-hystrix-1005
启动microservice-student-consumer-feign-80

http://localhost/student/getInfo
随机出现
{"code":200,"info":"业务数据xxxxx1004"}
{"code":200,"info":"业务数据xxxxx1005"}