一、FeignClient註解
FeignClient註解被@Target(ElementType.TYPE)修飾,表示FeignClient註解的作用目標在接口上
1 2 3 4 5 | @FeignClient(name = "github-client" , url = "https://api.github.com" , configuration = GitHubExampleConfig. class ) public interface GitHubClient { @RequestMapping(value = "/search/repositories" , method = RequestMethod.GET) String searchRepo(@RequestParam( "q" ) String queryStr); } |
聲明接口之後,在代碼中通過@Resource注入之後即可使用。@FeignClient標籤的常用屬性如下:
- name:指定FeignClient的名稱,如果項目使用了Ribbon,name屬性會作爲微服務的名稱,用於服務發現
- url: url一般用於調試,可以手動指定@FeignClient調用的地址
- decode404:當發生http 404錯誤時,如果該字段位true,會調用decoder進行解碼,否則拋出FeignException
- configuration: Feign配置類,可以自定義Feign的Encoder、Decoder、LogLevel、Contract
- fallback: 定義容錯的處理類,當調用遠程接口失敗或超時時,會調用對應接口的容錯邏輯,fallback指定的類必須實現@FeignClient標記的接口
- fallbackFactory: 工廠類,用於生成fallback類示例,通過這個屬性我們可以實現每個接口通用的容錯邏輯,減少重複的代碼
- path: 定義當前FeignClient的統一前綴
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | @FeignClient(name = "github-client" , url = "https://api.github.com" , configuration = GitHubExampleConfig. class , fallback = GitHubClient.DefaultFallback. class ) public interface GitHubClient { @RequestMapping(value = "/search/repositories" , method = RequestMethod.GET) String searchRepo(@RequestParam( "q" ) String queryStr); /** * 容錯處理類,當調用失敗時,簡單返回空字符串 */ @Component public class DefaultFallback implements GitHubClient { @Override public String searchRepo(@RequestParam( "q" ) String queryStr) { return "" ; } } } |
在使用fallback屬性時,需要使用@Component註解,保證fallback類被Spring容器掃描到,GitHubExampleConfig內容如下:
1 2 3 4 5 6 7 | @Configuration public class GitHubExampleConfig { @Bean Logger.Level feignLoggerLevel() { return Logger.Level.FULL; } } |
在使用FeignClient時,Spring會按name創建不同的ApplicationContext,通過不同的Context來隔離FeignClient的配置信息,在使用配置類時,不能把配置類放到Spring App Component scan的路徑下,否則,配置類會對所有FeignClient生效.
1 2 3 4 5 6 7 8 9 10 11 12 13 | @RestController @RequestMapping( "/v1/card" ) public class IndexApi { @PostMapping( "balance" ) @ResponseBody public Info index() { Info.Builder builder = new Info.Builder(); builder.withDetail( "x" , 2); builder.withDetail( "y" , 2); return builder.build(); } } |
Feign Client
1 2 3 4 5 6 7 8 9 10 11 12 13 | @FeignClient( name = "card" , url = "http://localhost:7913" , fallback = CardFeignClientFallback. class , configuration = FeignClientConfiguration. class ) @RequestMapping(value = "/v1/card" ) public interface CardFeignClient { @RequestMapping(value = "/balance" , method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE) Info info(); } |
if @RequestMapping is used on class, when invoke http /v1/card/balance, like this :
如果 @RequestMapping註解被用在FeignClient類上,當像如下代碼請求/v1/card/balance時,注意有Accept header:
1 2 3 4 | Content-Type:application/json Accept:application/json POST http: //localhost:7913/v1/card/balance |
那麼會返回 404。
如果不包含Accept header時請求,則是OK:
1 2 | Content-Type:application/json POST http: //localhost:7913/v1/card/balance |
或者像下面不在Feign Client上使用@RequestMapping註解,請求也是ok,無論是否包含Accept:
1 2 3 4 5 6 7 8 9 10 11 12 13 | @FeignClient( name = "card" , url = "http://localhost:7913" , fallback = CardFeignClientFallback. class , configuration = FeignClientConfiguration. class ) public interface CardFeignClient { @RequestMapping(value = "/v1/card/balance" , method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE) Info info(); } |
解決方案有三種,以feign爲例。
方法一
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 5000
該配置是讓Hystrix的超時時間改爲5秒
方法二
hystrix.command.default.execution.timeout.enabled: false
該配置,用於禁用Hystrix的超時時間
方法三
feign.hystrix.enabled: false
該配置,用於索性禁用feign的hystrix。該做法除非一些特殊場景,不推薦使用。