		<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

1.2.2 配置

server:
  port: 8090
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka
  instance:
    prefer-ip-address: true # 返回ip而不是host名称
#    ip-address: 127.0.0.1 # 指定自己的ip信息
    lease-expiration-duration-in-seconds: 15 # 服务失效时间，默认值90秒
    lease-renewal-interval-in-seconds: 5 # 服务续约(renew)的间隔，默认为30秒
spring:
  application:
    name: user-provider

1.2.3 开启注册发现

@SpringBootApplication
@EnableDiscoveryClient
public class UserProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserProviderApplication.class, args);
    }
}

1.2.4 接口API

@RestController
@RequestMapping("/user")
public class UserController {
    @Value("${server.port}")
    private String port;
    @Autowired
    private UserService userService;

    private Map<String, Object> data = null;

    @GetMapping("/{name}")
    public Object hello(@PathVariable String name) {
        String hello = userService.hello(name);
        data = new HashMap<>(4);
        data.put("port", port);
        data.put("msg", hello);
        return data;
    }
}

1.2.5 启动服务提供者

启动user-provider

2. 修改Feign消费者

2.1 主要依赖

		<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

2.2 配置文件

Feign默认有对Hystix的集成，默认情况下是关闭的。我们需要通过配置来开启：
application.yml：

server:
  port: 8080
spring:
  application:
    name: user-consumer-feign
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka
  instance:
    prefer-ip-address: true
feign:
  hystrix:
    enabled: true # Feign默认是集成了Hystrix的，只是默认关闭，这里开启Feign的熔断功能
hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 5000 # 设置hystrix的超时时间为5000ms

2.3 Hystrix支持

Feign中的Fallback配置不像Ribbon中那样简单。

2.3.1 编写Fallback处理类

我们要定义一个类UserServiceFallback，实现UserService接口，作为Fallback的处理类，同时要加入到Spring的IoC容器中：

@Component
public class UserServiceFallback implements UserService {
    /**
     * hello,${name}
     *
     * @param name
     * @return
     */
    @Override
    public String hello(String name) {
        return "系统异常，请稍后重试-【" + name + "】";
    }
}

2.3.2 指定Fallback实现类

在接口UserService上的注解@FeignClient里添加属性fallback = UserServiceFallback.class，指定Fallback实现类

@FeignClient(value = "user-provider",fallback = UserServiceFallback.class)
public interface UserService {
    /**
     * hello,${name}
     * @param name
     * @return
     */
    @GetMapping("/user/{name}")
    String hello(@PathVariable String name);
}

2.4 启动类上开启Feign注解

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients // 启用Feign功能
public class UserConsumerFeignApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserConsumerFeignApplication.class, args);
    }
}

3. 测试

依次启动Eureka注册中心、服务提供者user-provider，编写测试类：

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserConsumerFeignApplicationTests {

    @Autowired
    private UserService userService;

    @Test
    public void contextLoads() {
        for (int i = 0; i < 10; i++) {
            String map = userService.hello("Cindy" + i);
            System.err.println(map);
        }
    }
}

在user-provider启动时，运行测试类:
在这里插入图片描述
断开user-provider服务，运行测试类：

xudc

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Spring Cloud 学习 | - 07 - Feign方式断路器Hystrix

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