Spring Cloud Alibaba-Feign（十四）

简介

Feign makes writing java http clients easier（声明式http客户端）官方文档

整合Feign

• 加依赖

<!--version由父工程定义-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
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• 写注解

@EnableFeignClients
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• 写配置

无
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使用

package com.virgo.user.feignclient;

import com.virgo.entity.TblCar;
import com.virgo.user.configuration.GlobalFeignConfiguration;
import com.virgo.user.feignclient.fallbackFactory.LockCenterFeignClientFallbackFactory;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

/**
 * @author zhaozha
 * @date 2019/10/11 下午12:52
 */
@FeignClient(name = "lock-center", configuration = GlobalFeignConfiguration.class,fallbackFactory = LockCenterFeignClientFallbackFactory.class)
public interface LockCenterFeignClient {
    // 自动构建http://lock-center/lock/test/{id}
    @GetMapping("/lock/test/{id}")
    TblCar findById(@PathVariable(value="id") Long id);
}

// Controller
...
private final LockCenterFeignClient lockCenterFeignClient;
...
TblCar tblCar = lockCenterFeignClient.findById(4000002L);
...

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组成

接口	做用	默认值
Feign.Builder	Feign的入口	Feign.Builder
Client	Feign底层用什么去请求	LoadBalancerFeignClient(整合Ribbon)/fengn.Client.Default(不整合Ribbon)
Contract	契约，注解支持	SpringMvcContract
Encoder	编码器，用于将对象转换成HTTP请求消息体	SpringEncoder
Decoder	解码器，将响应消息体转换成对象	ResponseEntityDecoder
Logger	日志管理器	Slf4jLogger
RequestInterceptor	用于为每一个请求添加通用逻辑	无

日志级别

级别	打印内容
NONE(默认值)	不记录任何日志
BASIC	仅记录请求的方法/URL/响应状态码/执行时间
HEADERS	BASIC+请求和响应的header
FULL	记录请求和响应的header/body/元数据

日志配置

• 细粒度代码

  • yml

  Feign日志级别设置(代码)
  logging:
    level:
      com.virgo.user.feignclient.LockCenterFeignClient: debug
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  • 代码

  package com.virgo.user.feignclient;
  
  import com.virgo.entity.TblCar;
  import com.virgo.user.configuration.GlobalFeignConfiguration;
  import com.virgo.user.feignclient.fallbackFactory.LockCenterFeignClientFallbackFactory;
  import org.springframework.cloud.openfeign.FeignClient;
  import org.springframework.web.bind.annotation.GetMapping;
  import org.springframework.web.bind.annotation.PathVariable;
  
  /**
   * @author zhaozha
   * @date 2019/10/11 下午12:52
   */
  @FeignClient(name = "lock-center", configuration = GlobalFeignConfiguration.class,fallbackFactory = LockCenterFeignClientFallbackFactory.class)
  public interface LockCenterFeignClient {
  
      @GetMapping("/lock/test/{id}")
      TblCar findById(@PathVariable(value="id") Long id);
  }
  
  GlobalFeignConfiguration.class
  package com.virgo.user.configuration;
  
  import feign.Logger;
  import org.springframework.context.annotation.Bean;
  
  /**
   * @author zhaozha
   * @date 2019/10/11 下午1:18
   */
  public class GlobalFeignConfiguration {
      @Bean
      public Logger.Level level(){
          // 让feign打印全部请求的细节
          return Logger.Level.FULL;
      }
  }
  
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• 细粒度配置

feign:
  client:
    config:
      lock-center:
        loggerLevel: FULL
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• 全局代码

@EnableFeignClients(defaultConfiguration = GlobalFeignConfiguration.class)
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• 全局配置

feign:
  client:
    config:
      default:
        loggerLevel: FULL
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配置项

代码

配置项	做用
Logger.Level	指定日志级别
Retryer	指定重试策略
ErrorDecoder	指定错误解码器
Request.Options	超时时间
Collection	拦截器
SetterFactory	Hystrix相关

配置

feign:
  client:
    config:
      # 全局
      default:
        # 日志级别
        loggerLevel:
        # 链接超时时间
        connectTimeout:
        # 读取超时时间
        readTimeout:
        # 错误解码器
        errorDecoder:
        # 重试策略
        retryer:
        # 拦截器
        requestInterceptors:
        # 404错误码解码
        decode404:
        # 编码器
        encoder:
        # 解码器
        decoder:
        # 契约
        contract:
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继承

todo

多参数

@GetMapping("/lock/car/{carId}/user/{userId}")
TblCar findById(@PathVariable(value="carId") Long carId,@PathVariable(value="userId") Long userId);
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脱离ribbon

@FeignClient(name="",url="")
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feign & restTemplate

• 性能：restTemplate
• 可读性：feign

优化

feign:
  httpclient:
    # 让feign使用apache httpclient作请求；而不是默认的urlconnection
    enabled: true
    # feign的最大链接数
    max-connections: 200
    # feign单个路径的最大链接数
    max-connections-per-route: 50
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fallback & fallbackFactory

• fallback

// 1注解
@FeignClient(....,fallback=xxx.class)

// 2代码
package com.virgo.user.feignclient.fallback;

import com.virgo.entity.TblCar;
import com.virgo.user.feignclient.LockCenterFeignClient;
import org.springframework.stereotype.Component;

/**
 * @author zhaozha
 * @date 2019/10/16 下午3:36
 */
@Component
public class LockCenterFeignClientFallback implements LockCenterFeignClient {
    @Override
    public TblCar findById(Long id,Long userId) {
        return TblCar.builder().level(1).build();
    }

    @Override
    public TblCar testPost(String params) {
        return null;
    }
}



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• fallbackFactory（强于fallback，能够打印异常）

// 1注解
@FeignClient(....,fallbackFactory=xxx.class)

// 2代码
package com.virgo.user.feignclient.fallbackFactory;

import com.virgo.entity.TblCar;
import com.virgo.user.feignclient.LockCenterFeignClient;
import feign.hystrix.FallbackFactory;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

/**
 * @author zhaozha
 * @date 2019/10/16 下午4:02
 */
@Component
@Slf4j
public class LockCenterFeignClientFallbackFactory implements FallbackFactory<LockCenterFeignClient> {
    @Override
    public LockCenterFeignClient create(Throwable throwable) {
        return new LockCenterFeignClient() {
            @Override
            public TblCar findById(Long id,Long userId) {
                log.info("限流/降级",throwable);
                return TblCar.builder().level(1).build();
            }

            @Override
            public TblCar testPost(String params) {
                return null;
            }
        };
    }
}

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