1.创建对应的公用部分（如图所示）

package模块 1571014690(1).png

ProductFeign代码

@FeignClient(name = ServiceNameConstants.PRODUCT_SERVICE,fallbackFactory= ProductFeignFallbackFactory.class)
public interface ProductFeign {
    /**
     * @return  String
     */
    @GetMapping("/msg")
    String msg();

    /**
     * 根据IdList查找商品详细信息
     * @param idList
     * @return
     */
    @GetMapping(value = "/productInfo/listByIdList")
    List<ProductInfo> listByIdList(@RequestParam("idList") List<String> idList);

    @PutMapping(value = "/productInfo/decreaseStock")
    Integer decreaseStock(@RequestBody List<CartDTO> cartDTOList);
}

ProductFeignFallback代码

package com.zzw.core.api.feign.fallback;

import com.zzw.core.api.dto.product.CartDTO;
import com.zzw.core.api.feign.ProductFeign;
import com.zzw.core.api.po.product.ProductInfo;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import java.util.List;

/**
 * @author zhangzhiwen
 */
@Slf4j
@Data
@Component
public class ProductFeignFallback implements ProductFeign {
    private Throwable cause;

    @Override
    public String msg() {
        log.error("feign 查询失败", cause);
        return null;
    }

    @Override
    public List<ProductInfo> listByIdList(List<String> idList) {
        log.error("feign 根据idList查询详细信息失败 param={}",idList, cause);
        return null;
    }

    @Override
    public Integer decreaseStock(List<CartDTO> cartDTOList) {
        log.error("feign 扣减库存失败 param={}",cartDTOList, cause);
        return null;
    }
}

ProductFeignFallbackFactory代码

package com.zzw.core.api.feign.factory;

import com.zzw.core.api.feign.ProductFeign;
import com.zzw.core.api.feign.fallback.ProductFeignFallback;
import feign.hystrix.FallbackFactory;
import org.springframework.stereotype.Component;

/**
 * @author zhang
 */
@Component
public class ProductFeignFallbackFactory implements FallbackFactory<ProductFeign> {

    @Override
    public ProductFeign create(Throwable throwable) {
        ProductFeignFallback productFeignFallback = new ProductFeignFallback();
        productFeignFallback.setCause(throwable);
        return productFeignFallback;
    }
}

对应的配置文件 1571014947(1).png

spring.factories配置其他包自动注入代码

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.zzw.core.api.feign.fallback.ProductFeignFallback,\
  com.zzw.core.api.feign.factory.ProductFeignFallbackFactory

2.指定fegin客户端扫描地址

可以直接在@EnableFeignClients(basePackages = “com.zzw.core.api”)指定
也可以自定义注解（相对比较优雅）

自定义注解类

package com.zzw.core.security.annotation;

import org.springframework.cloud.openfeign.EnableFeignClients;

import java.lang.annotation.*;

/**
 * @author zhang
 * @date 2019/3/18
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@EnableFeignClients
public @interface EnableZzwFeignClients {
    /**
     * Alias for the {@link #basePackages()} attribute. Allows for more concise annotation
     * declarations e.g.: {@code @ComponentScan("org.my.pkg")} instead of
     * {@code @ComponentScan(basePackages="org.my.pkg")}.
     *
     * @return the array of 'basePackages'.
     */
    String[] value() default {};

    /**
     * Base packages to scan for annotated components.
     * <p>
     * {@link #value()} is an alias for (and mutually exclusive with) this attribute.
     * <p>
     * Use {@link #basePackageClasses()} for a type-safe alternative to String-based
     * package names.
     *
     * @return the array of 'basePackages'.
     */
    String[] basePackages() default {"com.zzw.core.api"};

    /**
     * Type-safe alternative to {@link #basePackages()} for specifying the packages to
     * scan for annotated components. The package of each class specified will be scanned.
     * <p>
     * Consider creating a special no-op marker class or interface in each package that
     * serves no purpose other than being referenced by this attribute.
     *
     * @return the array of 'basePackageClasses'.
     */
    Class<?>[] basePackageClasses() default {};

    /**
     * A custom <code>@Configuration</code> for all feign clients. Can contain override
     * <code>@Bean</code> definition for the pieces that make up the client, for instance
     * {@link feign.codec.Decoder}, {@link feign.codec.Encoder}, {@link feign.Contract}.
     *
     * @see  for the defaults
     */
    Class<?>[] defaultConfiguration() default {};

    /**
     * List of classes annotated with @FeignClient. If not empty, disables classpath scanning.
     *
     * @return
     */
    Class<?>[] clients() default {};
}

3.启动类添加注解

package com.zzw.order;

import com.zzw.core.security.annotation.EnableZzwFeignClients;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

/**
 * @author zhangzhiwen
 */
@SpringBootApplication
@EnableDiscoveryClient
@EnableZzwFeignClients
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

}

配置结束