Spring Cloud Alibaba-Feign（十四）

簡介

Feign makes writing java http clients easier（聲明式http客戶端）官方文檔

整合Feign

• 加依賴

<!--version由父工程定義-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
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• 寫註解

@EnableFeignClients
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• 寫配置

無
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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 {
    // 自動構建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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組成

接口	做用	默認值
Feign.Builder	Feign的入口	Feign.Builder
Client	Feign底層用什麼去請求	LoadBalancerFeignClient(整合Ribbon)/fengn.Client.Default(不整合Ribbon)
Contract	契約，註解支持	SpringMvcContract
Encoder	編碼器，用於將對象轉換成HTTP請求消息體	SpringEncoder
Decoder	解碼器，將響應消息體轉換成對象	ResponseEntityDecoder
Logger	日誌管理器	Slf4jLogger
RequestInterceptor	用於爲每一個請求添加通用邏輯	無

日誌級別

級別	打印內容
NONE(默認值)	不記錄任何日誌
BASIC	僅記錄請求的方法/URL/響應狀態碼/執行時間
HEADERS	BASIC+請求和響應的header
FULL	記錄請求和響應的header/body/元數據

日誌配置

• 細粒度代碼

  • yml

  Feign日誌級別設置(代碼)
  logging:
    level:
      com.virgo.user.feignclient.LockCenterFeignClient: debug
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  • 代碼

  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(){
          // 讓feign打印全部請求的細節
          return Logger.Level.FULL;
      }
  }
  
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• 細粒度配置

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

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

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

代碼

配置項	做用
Logger.Level	指定日誌級別
Retryer	指定重試策略
ErrorDecoder	指定錯誤解碼器
Request.Options	超時時間
Collection	攔截器
SetterFactory	Hystrix相關

配置

feign:
  client:
    config:
      # 全局
      default:
        # 日誌級別
        loggerLevel:
        # 鏈接超時時間
        connectTimeout:
        # 讀取超時時間
        readTimeout:
        # 錯誤解碼器
        errorDecoder:
        # 重試策略
        retryer:
        # 攔截器
        requestInterceptors:
        # 404錯誤碼解碼
        decode404:
        # 編碼器
        encoder:
        # 解碼器
        decoder:
        # 契約
        contract:
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繼承

todo

多參數

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

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

• 性能：restTemplate
• 可讀性：feign

優化

feign:
  httpclient:
    # 讓feign使用apache httpclient作請求；而不是默認的urlconnection
    enabled: true
    # feign的最大鏈接數
    max-connections: 200
    # feign單個路徑的最大鏈接數
    max-connections-per-route: 50
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fallback & fallbackFactory

• fallback

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

// 2代碼
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（強於fallback，能夠打印異常）

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

// 2代碼
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/降級",throwable);
                return TblCar.builder().level(1).build();
            }

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

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