Feign远程调用

1.引入jar包

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

2.添加注解@EnableFeignClients

package cn.itcast;

        import org.springframework.boot.SpringApplication;
        import org.springframework.cloud.client.SpringCloudApplication;
        import org.springframework.cloud.client.loadbalancer.LoadBalanced;
        import org.springframework.cloud.openfeign.EnableFeignClients;
        import org.springframework.context.annotation.Bean;
        import org.springframework.web.client.RestTemplate;

//@EnableCircuitBreaker
//@EnableDiscoveryClient
//@SpringBootApplication
//三个合并成一个
@EnableFeignClients
@SpringCloudApplication
public class ConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class);
        System.out.println("consumer-demo启动成功");
    }
    //注册这个对象把他给spring容器管理这样我们以后就可以在其他的方法中调用了控制反转（IOC）
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

3.编写接口

package cn.itcast.consumer.client;

import cn.itcast.consumer.pojp.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient("user-service")
public interface UserClient {
    @GetMapping("user/{id}")
    User queryById(@PathVariable("id") Long id);
}

4.修改controller方法

package cn.itcast.consumer.web;

import cn.itcast.consumer.client.UserClient;
import cn.itcast.consumer.pojp.User;
import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
@RequestMapping("consumer")
@DefaultProperties(defaultFallback = "queryByIdFallback")
public class ConsumerController {

    //这是在启动类的时候给spring 容器管理了
   /* @Autowired
    private RestTemplate restTemplate;*/
   // @Autowired
   // private DiscoveryClient discoverClient;
   // private RibbonLoadBalancerClient client;

    @Autowired
    private UserClient userClient;

    @GetMapping("{id}")
   /* @HystrixCommand(commandProperties = {
            @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value = "3000") //超市时长调成了3秒
    })*/
    public User queryById(@PathVariable("id")Long id){
        return userClient.queryById(id);
    }

    public String queryByIdFallback(Long id){
        return "不好意思，服务器太拥挤";
    }
    public String queryByIdFallback(){
        return "不好意思，服务器太拥挤";
    }

/*    @GetMapping("{id}")
    public User queryById(@PathVariable("id")Long id){
        //根据服务id获取实例，因为可能有几台这边用得是list
      //  List<ServiceInstance> instances = discoverClient.getInstances("user-service");
       // 从实例中取出ip和端口因为我们这只有一个所以取list(0)
     //   ServiceInstance instance = client.choose("user-service");
      //  ServiceInstance instance  = instances.get(0);
     //   String url = "http://"+instance.getHost()+":"+instance.getPort()+"/user/"+id;
        String url = "http://user-service/user/"+id;
        User user = restTemplate.getForObject(url,User.class);
        return user;
    }*/
}

可能要把user-service中的user-service的睡眠去掉

package cn.itcast.user.service;


import cn.itcast.user.mapper.UserMapper;
import cn.itcast.user.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    public User queryBtyId(Long id){
       /* try {
            Thread.sleep(2000L);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }*/
        return userMapper.selectByPrimaryKey(id);
    }

    @Transactional //事务
    public void insertUser(User user){
        userMapper.insert(user);
    }
}

#配置熔断
1添加配置

server:
  port: 8088
spring:
  application:
    name: consumer-service #起名字
#注册到服务中心
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka, http://127.0.0.1:10087/eureka
    #5秒拉取服务列表
    registry-fetch-interval-seconds: 5
#切换方式为随机默认是轮询 没有必要用这个写着让你看看有这么个东西
#user-service:
 # ribbon:
 #   NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

#配置feign超时
feign:
  hystrix:
    enabled: true
ribbon:
  ConnectionTimeOut: 500
  ReadTimeOut: 20000

#配置全局超时
server:
  port: 8088
spring:
  application:
    name: consumer-service #起名字
#注册到服务中心
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka, http://127.0.0.1:10087/eureka
    #5秒拉取服务列表
    registry-fetch-interval-seconds: 5
#切换方式为随机默认是轮询 没有必要用这个写着让你看看有这么个东西
#user-service:
 # ribbon:
 #   NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

#配置feign超时
feign:
  hystrix:
    enabled: true
ribbon:
  ConnectionTimeOut: 500
  ReadTimeOut: 20000

#配置全局超时
hystrix:
  command:
   default:
    execution:
     isolation:
      thread:
       timeoutInMilliseconds: 3000

2.方法配置

package cn.itcast.consumer.client;

import cn.itcast.consumer.pojp.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient(value = "user-service",fallback = UserClientFallback.class )
public interface UserClient {
    @GetMapping("user/{id}")
    User queryById(@PathVariable("id") Long id);
}

3。实现方法

package cn.itcast.consumer.client;

import cn.itcast.consumer.pojp.User;
import org.springframework.stereotype.Component;

@Component
public class UserClientFallback implements UserClient {
    @Override
    public User queryById(Long id) {
        User user = new User();
        user.setName("未查询用户");
        return user;
    }
}