OpenFegin的日志打印功能是什么？Feign提供了日志打印功能，可以通过配置来调整日志级别，从而了解Feign执行Http请求的细节。通俗地说，就是对Feign接口的调用情况进行监控和输出。
日志级别
-
NONE 默认的,不显示任何日志;
-
BASIC 仅记录请求方法、URL、响应状态码及执行时间;
-
HEADERS 除了BASIC中定义的信息之外,还打印请求和响应的头信息;
-
FULL 除了HEADERS中定义的信息之外，还打印请求和响应的正文及元数据。
配置日志
@Configuration
public class FeignLogConfiguration {
@Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.HEADERS;
// return Logger.Level.FULL;
}
}
FeignLogConfiguration类上添加了@Configuration注解，说明是全局配置，若注释掉此注解，则开启了局部配置。在yaml文件中配置哪个接口需要以什么日志级别进行监控：
logging.level.com.swagger.demo.api.GithubFeignClient = DEBUG
之所以把Feign接口的日志级别设置成DEBUG，是因为Feign的Logger.Level只对DEBUG作出响应。测试用例复用《Spring注解之@FeignClient注解使用方法》中的wiener/github/listContributors，依然调用 GithubFeignClient#listContributors。如果开启局部配置，就需要使用如下Client：
import com.swagger.demo.bean.Contributor;
import com.swagger.demo.config.FeignLogConfiguration;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import java.util.ArrayList;
import java.util.List;
@FeignClient(name = "github", url = "${self.github.url}",
configuration = FeignLogConfiguration.class,
fallback = GithubFeignClient.DefaultFallback.class)
public interface GithubFeignClient {
@GetMapping(value = "/repos/{owner}/{repo}/contributors")
ResponseEntity<List<Contributor>> listContributors(
@PathVariable("owner") String owner,
@PathVariable("repo") String repo);
/**
* 容错处理类，当调用失败时，简单返回空list
*/
@Component
class DefaultFallback implements GithubFeignClient {
@Override
public ResponseEntity<List<Contributor>> listContributors(
@PathVariable("owner") String owner,
@PathVariable("repo") String repo) {
return new ResponseEntity(new ArrayList<>(), HttpStatus.BAD_REQUEST);
}
}
}
后台日志查看
切换FeignLogConfiguration中的日志级别并启动项目，访问wiener/github/listContributors，则可以看到内容不同的日志。
2022-02-10 20:20:16.792 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] ---> GET https://api.github.com/repos/openFeign/feign/contributors HTTP/1.1
2022-02-10 20:20:16.792 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] ---> END HTTP (0-byte body)
2022-02-10 20:20:17.119 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] <--- HTTP/1.1 200 OK (326ms)
2022-02-10 20:20:17.119 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] accept-ranges: bytes
2022-02-10 20:20:17.119 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] access-control-allow-origin: *
2022-02-10 20:20:17.119 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] access-control-expose-headers: ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Used, X-RateLimit-Resource, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type, X-GitHub-SSO, X-GitHub-Request-Id, Deprecation, Sunset
...
2022-02-10 20:20:17.120 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] x-ratelimit-reset: 1644496768
2022-02-10 20:20:17.120 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] x-ratelimit-resource: core
2022-02-10 20:20:17.120 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] x-ratelimit-used: 11
2022-02-10 20:20:17.120 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] x-xss-protection: 0
2022-02-10 20:20:17.272 DEBUG 15199 --- [nio-8087-exec-9] com.swagger.demo.api.GithubFeignClient : [GithubFeignClient#listContributors] <--- END HTTP (28116-byte body)