一、FeignClient注解
FeignClient注解被@Target(ElementType.TYPE)修饰,表示FeignClient注解的作用目标在接口上
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);
} |
声明接口之后,在代码中通过@Resource注入之后即可使用。@FeignClient标签的常用属性如下:
- name:指定FeignClient的名称,如果项目使用了Ribbon,name属性会作为微服务的名称,用于服务发现
- url: url一般用于调试,可以手动指定@FeignClient调用的地址
- decode404:当发生http 404错误时,如果该字段位true,会调用decoder进行解码,否则抛出FeignException
- configuration: Feign配置类,可以自定义Feign的Encoder、Decoder、LogLevel、Contract
- fallback: 定义容错的处理类,当调用远程接口失败或超时时,会调用对应接口的容错逻辑,fallback指定的类必须实现@FeignClient标记的接口
- fallbackFactory: 工厂类,用于生成fallback类示例,通过这个属性我们可以实现每个接口通用的容错逻辑,减少重复的代码
- path: 定义当前FeignClient的统一前缀
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);
/**
* 容错处理类,当调用失败时,简单返回空字符串
*/
@Component
public class DefaultFallback implements GitHubClient {
@Override
public String searchRepo(@RequestParam( "q" ) String queryStr) {
return "" ;
}
}
} |
在使用fallback属性时,需要使用@Component注解,保证fallback类被Spring容器扫描到,GitHubExampleConfig内容如下:
1
2
3
4
5
6
7
|
@Configuration public class GitHubExampleConfig {
@Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
} |
在使用FeignClient时,Spring会按name创建不同的ApplicationContext,通过不同的Context来隔离FeignClient的配置信息,在使用配置类时,不能把配置类放到Spring App Component scan的路径下,否则,配置类会对所有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注解被用在FeignClient类上,当像如下代码请求/v1/card/balance时,注意有Accept header:
1
2
3
4
|
Content-Type:application/json Accept:application/json POST http: //localhost:7913/v1/card/balance
|
那么会返回 404。
如果不包含Accept header时请求,则是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注解,请求也是ok,无论是否包含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();
} |
解决方案有三种,以feign为例。
方法一
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 5000
该配置是让Hystrix的超时时间改为5秒
方法二
hystrix.command.default.execution.timeout.enabled: false
该配置,用于禁用Hystrix的超时时间
方法三
feign.hystrix.enabled: false
该配置,用于索性禁用feign的hystrix。该做法除非一些特殊场景,不推荐使用。