从零开始学spring cloud(十) -------- hystrix简单代码示例

一、官网文档阅读

较低级别的服务中的服务故障可能导致级联故障一直到用户。当对特定服务的调用超过circuitBreaker.requestVolumeThreshold（默认值：20个请求）且失败百分比大于circuit.rolllingStats.timeInMilliseconds定义的滚动窗口中的circuitBreaker.errorThresholdPercentage（默认值：> 50％）时（默认值：10秒），电路打开，没有拨打电话。在出现错误和开路的情况下，开发人员可以提供回退。

二、示例

添加hystrix依赖

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

修改movie服务的controller

 1 package com.zwjk.cloud.controller;
 2 
 3 import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
 4 import com.zwjk.cloud.entity.User;
 5 import org.springframework.beans.factory.annotation.Autowired;
 6 import org.springframework.beans.factory.annotation.Value;
 7 import org.springframework.cloud.client.ServiceInstance;
 8 import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
 9 import org.springframework.web.bind.annotation.GetMapping;
10 import org.springframework.web.bind.annotation.PathVariable;
11 import org.springframework.web.bind.annotation.RestController;
12 import org.springframework.web.client.RestTemplate;
13 
14 /**
15  * @author : Jixiaohu
16  * @Date : 2019-04-11.
17  * @Time : 9:38.
18  * @Description :
19  */
20 @RestController
21 public class MovieController {
22 
23     @Autowired
24     private RestTemplate restTemplate;
25 
26     @Value("${user.userServicePath}")
27     private String userServicePath;
28 
29     @GetMapping("/movie/{id}")
30     @HystrixCommand(fallbackMethod = "findByIdFallback")
31     public User findById(@PathVariable Long id) {
32         return this.restTemplate.getForObject(this.userServicePath + id, User.class);
33     }
34 
35 
36     public User findByIdFallback(Long id) {
37         User user = new User();
38         user.setId(0L);
39         user.setName("失败");
40         return user;
41     }
42 }

这边需要注意的是，fallbackMethod方法的返回值和入参，必须和原方法一致，下面进行测试：

可以看到，这里返回了正常的结果，下面停掉user服务

可以看到，这里返回的结果，就是fallbackMethod里面返回的内容，hystrix就起了作用。

下面，继续看一下

Feign Hystrix Support

参考官网使用示例：

 1 @FeignClient(name = "hello", fallback = HystrixClientFallback.class)
 2 protected interface HystrixClient {
 3     @RequestMapping(method = RequestMethod.GET, value = "/hello")
 4     Hello iFailSometimes();
 5 }
 6 
 7 static class HystrixClientFallback implements HystrixClient {
 8     @Override
 9     public Hello iFailSometimes() {
10         return new Hello("fallback");
11     }
12 }

在配置文件中，增加开启feign使用断路器

feign:
  hystrix:
    enabled: true

按照示例，我们在movie服务中，新增UserFeignClientFallback类

 1 package com.zwjk.cloud.fegin;
 2 
 3 import com.zwjk.cloud.entity.User;
 4 import org.springframework.stereotype.Component;
 5 
 6 /**
 7  * @author : Jixiaohu
 8  * @Date : 2019-04-17.
 9  * @Time : 18:20.
10  * @Description :
11  */
12 @Component
13 public class UserFeignClientFallback implements UserFeignClient {
14     @Override
15     public User findById(Long id) {
16         User user = new User();
17         user.setId(0L);
18         return user;
19     }
20 }

在fegin上增加相应的注解：

 1 package com.zwjk.cloud.fegin;
 2 
 3 import com.zwjk.cloud.entity.User;
 4 import org.springframework.cloud.openfeign.FeignClient;
 5 import org.springframework.web.bind.annotation.GetMapping;
 6 import org.springframework.web.bind.annotation.PathVariable;
 7 import org.springframework.web.bind.annotation.PostMapping;
 8 import org.springframework.web.bind.annotation.RequestBody;
 9 
10 /**
11  * @author : Jixiaohu
12  * @Date : 2019-04-12.
13  * @Time : 16:50.
14  * @Description :
15  */
16 @FeignClient(name = "microservice-provider-user", fallback = UserFeignClientFallback.class)
17 public interface UserFeignClient {
18     //@PathVariable得设置value
19     @GetMapping("/simple/{id}")
20     User findById(@PathVariable("id") Long id); //@PathVariable得设置value
21 }

启动项目，进行测试，

同样的，停掉user服务，再次访问这个地址：

就可以实现熔断服务

当一个项目中，有个feign时，如何禁用一些feign的hystrix？

查看一下官网文档

通过配置加上feignBuilder,就可以禁用指定fegin的hystrix

查看一下代码实现：

 1 package com.zwjk.cloud.controller;
 2 
 3 import com.zwjk.cloud.entity.User;
 4 import com.zwjk.cloud.fegin.UserFeignClient2;
 5 import com.zwjk.cloud.fegin.UserFeignClient;
 6 import org.springframework.beans.factory.annotation.Autowired;
 7 import org.springframework.web.bind.annotation.GetMapping;
 8 import org.springframework.web.bind.annotation.PathVariable;
 9 import org.springframework.web.bind.annotation.RestController;
10 
11 /**
12  * @author : Jixiaohu
13  * @Date : 2019-04-11.
14  * @Time : 9:38.
15  * @Description :
16  */
17 @RestController
18 public class MovieController {
19 
20     @Autowired
21     private UserFeignClient userFeignClient;
22 
23     @Autowired
24     private UserFeignClient2 userFeignClient2;
25 
26     @GetMapping("/movie/{id}")
27     public User findById(@PathVariable Long id) {
28         return this.userFeignClient.findById(id);
29     }
30 
31     @GetMapping("/{serviceName}")
32     public String findServiceInfoFromEurekaByServiceName(@PathVariable String serviceName) {
33         return this.userFeignClient2.findServiceInfoFromEurekaByServiceName(serviceName);
34     }
35 
36 
37 }

两个fegin：

 1 package com.zwjk.cloud.fegin;
 2 
 3 import com.zwjk.cloud.entity.User;
 4 import com.zwjk.config.UserConfiguration;
 5 import feign.Param;
 6 import feign.RequestLine;
 7 import org.springframework.cloud.openfeign.FeignClient;
 8 
 9 /**
10  * @author : Jixiaohu
11  * @Date : 2019-04-12.
12  * @Time : 16:50.
13  * @Description :
14  */
15 @FeignClient(name = "microservice-provider-user", configuration = UserConfiguration.class, fallback =
16     UserFeignClientFallback.class)
17 public interface UserFeignClient {
18     //@PathVariable得设置value
19     @RequestLine("GET /simple/{id}")
20     User findById(@Param("id") Long id); //@PathVariable得设置value
21 
22 }

 1 package com.zwjk.cloud.fegin;
 2 
 3 import com.zwjk.config.UserConfiguration2;
 4 import org.springframework.cloud.openfeign.FeignClient;
 5 import org.springframework.web.bind.annotation.PathVariable;
 6 import org.springframework.web.bind.annotation.RequestMapping;
 7 
 8 /**
 9  * @author : Jixiaohu
10  * @Date : 2019-04-13.
11  * @Time : 11:23.
12  * @Description :
13  */
14 @FeignClient(name = "xxxx", url = "http://192.168.1.114:8761/", configuration = UserConfiguration2.class)
15 public interface UserFeignClient2 {
16     @RequestMapping(value = "/eureka/apps/{serviceName}")
17     public String findServiceInfoFromEurekaByServiceName(@PathVariable("serviceName") String serviceName);
18 }

两个fallback

 1 package com.zwjk.cloud.fegin;
 2 
 3 import org.springframework.stereotype.Component;
 4 
 5 /**
 6  * @author : Jixiaohu
 7  * @Date : 2019-04-17.
 8  * @Time : 18:20.
 9  * @Description :
10  */
11 @Component
12 public class UserFeignClient2Fallback implements UserFeignClient2 {
13 
14     @Override
15     public String findServiceInfoFromEurekaByServiceName(String serviceName) {
16         return "hahahha";
17     }
18 }

 1 package com.zwjk.cloud.fegin;
 2 
 3 import com.zwjk.cloud.entity.User;
 4 import org.springframework.stereotype.Component;
 5 
 6 /**
 7  * @author : Jixiaohu
 8  * @Date : 2019-04-17.
 9  * @Time : 18:20.
10  * @Description :
11  */
12 @Component
13 public class UserFeignClientFallback implements UserFeignClient {
14     @Override
15     public User findById(Long id) {
16         User user = new User();
17         user.setId(0L);
18         return user;
19     }
20 }

看一下两个配置文件

 1 package com.zwjk.config;
 2 
 3 import feign.Contract;
 4 import feign.Logger;
 5 import org.springframework.context.annotation.Bean;
 6 import org.springframework.context.annotation.Configuration;
 7 
 8 /**
 9  * @author : Jixiaohu
10  * @Date : 2019-04-13.
11  * @Time : 10:20.
12  * @Description :
13  */
14 @Configuration
15 public class UserConfiguration {
16 
17     @Bean
18     public Contract feignContract() {
19         return new feign.Contract.Default();
20     }
21 
22     @Bean
23     Logger.Level feignLoggerLevel() {
24         return Logger.Level.FULL;
25     }
26 }

 1 package com.zwjk.config;
 2 
 3 import feign.Feign;
 4 import feign.auth.BasicAuthRequestInterceptor;
 5 import org.springframework.context.annotation.Bean;
 6 import org.springframework.context.annotation.Configuration;
 7 import org.springframework.context.annotation.Scope;
 8 
 9 /**
10  * @author : Jixiaohu
11  * @Date : 2019-04-13.
12  * @Time : 11:25.
13  * @Description :
14  */
15 @Configuration
16 public class UserConfiguration2 {
17     @Bean
18     public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
19         return new BasicAuthRequestInterceptor("user", "password123");
20     }
21 
22     @Configuration
23     public class FooConfiguration {
24         @Bean
25         @Scope("prototype")
26         public Feign.Builder feignBuilder() {
27             return Feign.builder();
28         }
29     }
30 }

启动服务，进行测试

下面，我们停掉eureka，和user服务，在一次查看返回结果

启用hystrix的返回结果如下：

没有启用hystrix的返回结果，提示500错误

从中，可以看出，hytrix的熔断，可以有很细的粒度。

如果想要查看fallback回退的原因，可以使用可以使用@FeignClient中的fallbackFactory属性。

看一下如何实现？

参考一下官网文档：

先写一个hystrixFactory：

 1 package com.zwjk.cloud.fegin;
 2 
 3 import com.zwjk.cloud.entity.User;
 4 import feign.hystrix.FallbackFactory;
 5 import org.slf4j.Logger;
 6 import org.slf4j.LoggerFactory;
 7 import org.springframework.stereotype.Component;
 8 
 9 /**
10  * @author : Jixiaohu
11  * @Date : 2019-04-17.
12  * @Time : 19:37.
13  * @Description :
14  */
15 @Component
16 public class UserFeginClientFactory implements FallbackFactory<UserFeignClient> {
17 
18     private static final Logger Log = LoggerFactory.getLogger(UserFeginClientFactory.class);
19 
20     @Override
21     public UserFeignClient create(Throwable cause) {
22         UserFeginClientFactory.Log.info("fallback:reason was : {}", cause.getMessage());
23         return id -> {
24             User user = new User();
25             user.setId(-1L);
26             user.setName("haha");
27             return user;
28         };
29     }
30 }

修改一下原feignClient

 1 package com.zwjk.cloud.fegin;
 2 
 3 import com.zwjk.cloud.entity.User;
 4 import org.springframework.cloud.openfeign.FeignClient;
 5 import org.springframework.web.bind.annotation.GetMapping;
 6 import org.springframework.web.bind.annotation.PathVariable;
 7 import org.springframework.web.bind.annotation.PostMapping;
 8 import org.springframework.web.bind.annotation.RequestBody;
 9 
10 /**
11  * @author : Jixiaohu
12  * @Date : 2019-04-12.
13  * @Time : 16:50.
14  * @Description :
15  */
16 @FeignClient(name = "microservice-provider-user", fallbackFactory =
17     UserFeginClientFactory.class)
18 public interface UserFeignClient {
19     //@PathVariable得设置value
20     @GetMapping("/simple/{id}")
21     User findById(@PathVariable("id") Long id); //@PathVariable得设置value
22 }

启动user服务，movie服务，先正常访问：

然后关闭user服务，会发现控制台开始打印日志：

这是为什么呢？因为此时，断路器并没有打开，实际的原因是TimeoutException

当断路器打开时，就会答应异常的信息。

posted on 2019-04-17 20:26 小~虎阅读(530) 评论(0) 编辑收藏举报