在spring cloud的项目中，使用Fegin做多个服务之间的调用，是很常见的事情，但是调用失败后虽然能进入熔断器中，但是具体的失败原因，或者日志，如果能看到，那么对开发调试，将会有很大的帮助。

步骤

1、配置FeignConfig

@Configuration
public class FeignConfig {

    /**
     * 配置请求重试
     *
     */
    @Bean
    public Retryer feignRetryer() {
        return new Retryer.Default(200, SECONDS.toMillis(2), 10);
    }

    /**
     * 设置请求超时时间
     *默认
         * public Options() {
         * this(10 * 1000, 60 * 1000);
         * }
     *
     */
    @Bean
    Request.Options feignOptions() {
        return new Request.Options(60 * 1000, 60 * 1000);
    }

    /**
     * 打印请求日志
     * @return
     */
    @Bean
    public feign.Logger.Level multipartLoggerLevel() {
        return feign.Logger.Level.FULL;
    }

}

2、配置 FeignClient

@FeignClient(value = "test-service", fallback = TestServiceHystrix.class, configuration = FeignConfig.class)
public interface TestServiceClient {

    @PostMapping( value = "/upload",produces = {MediaType.APPLICATION_JSON_UTF8_VALUE},consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
     UpLoadResult upload(@RequestParam("upload") MultipartFile file);
}

3、请求接口，查看控制台日志

2017-10-09 19:31:01.438 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] 

c.x.test.client.testServiceClient       :

 [testServiceClient#upload] ---> POST http://test-service/upload?

upload=org.springframework.mock.web.MockMultipartFile%4021d2b412 HTTP/1.1
2017-10-09 19:31:01.438 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : 

[testServiceClient#upload] Accept: application/json;charset=UTF-8

2017-10-09 19:31:01.439 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : 

[testServiceClient#upload] Content-Type: multipart/form-data

2017-10-09 19:31:01.439 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       :

 [testServiceClient#upload] ---> END HTTP (0-byte body)

[test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@45a92394: startup date [Mon Oct 09 19:31:01 CST 2017]; parent: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@64b3b1ce
2017-10-09 19:31:01.533  INFO 

[test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2017-10-09 19:31:01.776  INFO

 [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.netflix.config.ChainedDynamicProperty  : Flipping property: test-test-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2017-10-09 19:31:01.819  INFO [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.n.u.concurrent.ShutdownEnabledTimer    : Shutdown hook installed for: NFLoadBalancer-PingTimer-test-test-service
2017-10-09 19:31:01.824  INFO

 [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.netflix.loadbalancer.BaseLoadBalancer  : Client: test-test-service instantiated a LoadBalancer: DynamicServerListLoadBalancer:{NFLoadBalancer:name=test-test-service,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2017-10-09 19:31:01.830  INFO [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.n.l.DynamicServerListLoadBalancer      : Using serverListUpdater PollingServerListUpdater
2017-10-09 19:31:01.851  INFO [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.netflix.config.ChainedDynamicProperty  : Flipping property: test-test-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2017-10-09 19:31:01.852  INFO [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.n.l.DynamicServerListLoadBalancer      : 

DynamicServerListLoadBalancer for client test-test-service initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=test-test-service,current list of Servers=[10.10.0.176:8771],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone; Instance count:1;   Active connections count: 0;    Circuit breaker tripped count: 0;   Active connections per server: 0.0;]

},Server stats: [[Server:10.20.0.176:8700;  Zone:defaultZone;

    Total Requests:0;   Successive connection failure:0;    Total blackout seconds:0;   Last connection made:Thu Jan 01 08:00:00 CST 1970;  First connection made: Thu Jan 01 08:00:00 CST 1970;    Active Connections:0;   total failure count in last (1000) msecs:0; average resp time:0.0;  90 percentile resp time:0.0;    95 percentile resp time:0.0;    min resp time:0.0;  max resp time:0.0;  stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@15044fde
2017-10-09 19:31:02.047 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] <--- HTTP/1.1 500  (607ms)
2017-10-09 19:31:02.047 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] cache-control: no-cache, no-store, max-age=0, must-revalidate
2017-10-09 19:31:02.047 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] connection: close
2017-10-09 19:31:02.047 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] content-type: application/json;charset=UTF-8
2017-10-09 19:31:02.047 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] date: Mon, 09 Oct 2017 11:31:07 GMT
2017-10-09 19:31:02.047 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] expires: 0
2017-10-09 19:31:02.048 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] pragma: no-cache
2017-10-09 19:31:02.048 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] transfer-encoding: chunked
2017-10-09 19:31:02.048 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] x-application-context: test-test-service:dev:8771
2017-10-09 19:31:02.048 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] x-content-type-options: nosniff
2017-10-09 19:31:02.048 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] x-frame-options: DENY
2017-10-09 19:31:02.048 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] x-xss-protection: 1; mode=block
2017-10-09 19:31:02.048 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload]
2017-10-09 19:31:02.049 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload]

 {
  "code" : 500,
  "error" : "Internal Server Error",
  "data" : null
}

2017-10-09 19:31:02.049 DEBUG [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.test.client.testServiceClient       : [testServiceClient#upload] <--- END HTTP (72-byte body)
2017-10-09 19:31:02.061  INFO [test-sys-test-service,e2818797113202e3,e2818797113202e3,true] 12972 --- [nio-8773-exec-2] c.x.t.c.hystrix.PlUserServiceHystrix     : ---upload hystrix---

从我的日志中可以看到，这次请求失败了，并且能看到发出的请求url，方法类型，返回数据，负载均衡信息，请求的具体的集群ip等，这对我们调试有很大的帮助

关键设置

    @Bean
    public feign.Logger.Level multipartLoggerLevel() {
        return feign.Logger.Level.FULL;
    }

//-----------------------------------
configuration = FeignConfig.class

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