Gateway调用Feign失败的问题

问题

服务B 经过Feign 能够正常调通 服务A
网关Gateway却不能经过Feign调通服务A

解决思路

1. 修改日志的输出级别为DEBUG
2. 建立feign的配置文件，设置feign的日志输出级别为全部

/** * Feign 配置 * @author: itdragons * @time: 2020/4/29 5:14 下午 */
@Configuration
public class FeignConfig {

    @Bean
    Logger.Level feignLevel() {
     	//这里记录全部
        return Logger.Level.FULL;
    }

3. gateway经过feign调用服务A，观察日志：

feign.codec.DecodeException: No qualifying bean of type 'org.springframework.boot.autoconfigure.http.HttpMessageConverters' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
	at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:187)
	at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:147)
	at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:80)
	at feign.hystrix.HystrixInvocationHandler$1.run(HystrixInvocationHandler.java:109)

经过日志可见HttpMessageConverters注入失败。

4. 修改feign的配置文件，注入Decoder。

import feign.Logger;
import feign.codec.Decoder;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.cloud.openfeign.support.ResponseEntityDecoder;
import org.springframework.cloud.openfeign.support.SpringDecoder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import java.util.ArrayList;
import java.util.List;

/** * Feign 配置 * @author: itdragons * @time: 2020/4/29 5:14 下午 */
@Configuration
public class FeignConfig {

    @Bean
    Logger.Level feignLevel() {
        return Logger.Level.FULL;
    }

    @Bean
    public Decoder feignDecoder() {
        return new ResponseEntityDecoder(new SpringDecoder(feignHttpMessageConverter()));
    }

    public ObjectFactory<HttpMessageConverters> feignHttpMessageConverter() {
        final HttpMessageConverters httpMessageConverters = new HttpMessageConverters(new PhpMappingJackson2HttpMessageConverter());
        return new ObjectFactory<HttpMessageConverters>() {
            @Override
            public HttpMessageConverters getObject() throws BeansException {
                return httpMessageConverters;
            }
        };
    }

    public class PhpMappingJackson2HttpMessageConverter extends MappingJackson2HttpMessageConverter {
        PhpMappingJackson2HttpMessageConverter(){
            List<MediaType> mediaTypes = new ArrayList<>();
            mediaTypes.add(MediaType.valueOf(MediaType.TEXT_HTML_VALUE + ";charset=UTF-8"));
            setSupportedMediaTypes(mediaTypes);
        }
    }
}

参考：https://www.jianshu.com/p/5461eb5386a8