Spring Cloud Feign 之日誌自定義擴展
環境信息: java 1.8、Spring boot 1.5.10.RELEASE、spring cloud-Edgware.SR3、maven 3.3+
與外部HTTP接口交互時需要記錄一些請求和響應日誌來排查問題，雖然Feign支持但它的日誌是Debug級別，並不符合我們在生產中使用INFO級別日誌要求，所以這章介紹下自定義日誌輸出。
分析Spring Cloud Feign 默認日誌
首先看下spring cloud feign 對日誌輸出的處理
package org.springframework.cloud.netflix.feign;
import feign.Logger;
/**
* Allows an application to use a custom Feign {@link Logger}.
*
* @author Venil Noronha
*/
public interface FeignLoggerFactory {
/**
* Factory method to provide a {@link Logger} for a given {@link Class}.
*
* @param type the {@link Class} for which a {@link Logger} instance is to be created
* @return a {@link Logger} instance
*/
public Logger create(Class<?> type);
}通過源碼我們知道spring cloud feign 已經對feign的日誌輸出這塊做了擴展，當然feign本身也可以，這裏針對spring cloud feign 進行講解。
FeignLoggerFactory是Feign日誌工廠接口類，DefaultFeignLoggerFactory是它的默認實現，spring cloud feign 就是用的 DefaultFeignLoggerFactory
@Override
public Logger create(Class<?> type) {
return this.logger != null ? this.logger : new Slf4jLogger(type);
}默認日誌工廠使用Slf4jLogger日誌，然後我們看下源碼
package feign.slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import feign.Request;
import feign.Response;
public class Slf4jLogger extends feign.Logger {
private final Logger logger;
public Slf4jLogger() {
this(feign.Logger.class);
}
public Slf4jLogger(Class<?> clazz) {
this(LoggerFactory.getLogger(clazz));
}
public Slf4jLogger(String name) {
this(LoggerFactory.getLogger(name));
}
Slf4jLogger(Logger logger) {
this.logger = logger;
}
@Override
protected void logRequest(String configKey, Level logLevel, Request request) {
if (logger.isDebugEnabled()) {
super.logRequest(configKey, logLevel, request);
}
}
@Override
protected Response logAndRebufferResponse(String configKey, Level logLevel,
Response response,long elapsedTime) throws IOException {
if (logger.isDebugEnabled()) {
return super.logAndRebufferResponse(configKey, logLevel, response, elapsedTime);
}
return response;
}
@Override
protected void log(String configKey, String format, Object... args) {
// Not using SLF4J's support for parameterized messages (even though it would be more efficient) because it would
// require the incoming message formats to be SLF4J-specific.
if (logger.isDebugEnabled()) {
logger.debug(String.format(methodTag(configKey) + format, args));
}
}
}看到這裏就知道爲什麼Spring Cloud Feign 日誌輸出的是Debug級別日誌了。
自定Spring Cloud Feign日誌輸出
參考DefaultFeignLoggerFactory類實現自己的日誌工廠實現類。
場景說明：將原有的debug級別，修改成info級別
第一步:實現FeignLoggerFactory工廠接口,InfoFeignLoggerFactory 是FeignConfig靜態內部類
/**
* feign info 日誌工廠
*/
public static class InfoFeignLoggerFactory implements FeignLoggerFactory {
@Override
public Logger create(Class<?> type) {
return new InfoFeignLogger(LoggerFactory.getLogger(type));
}
}第二部: 繼承feign.Logger實現info級別日誌輸出，InfoFeignLogger使用slf4j日誌工具，此處只是簡單的實現了info級別日誌輸出，如果想效率更高請參考Slf4jLogger添加一些日記級別判斷
/**
* info feign 日誌
* @author: sunshaoping
* @date: Create by in 下午3:29 2018/8/8
*/
public class InfoFeignLogger extends feign.Logger {
private final Logger logger;
public InfoFeignLogger(Logger logger) {
this.logger = logger;
}
@Override
protected void log(String configKey, String format, Object... args) {
if (logger.isInfoEnabled()) {
logger.info(String.format(methodTag(configKey) + format, args));
}
}
}第三部:日誌工廠InfoFeignLoggerFactory註冊到spring 容器中，使用spring java Config
/**
* feign 配置
* @author: sunshaoping
* @date: Create by in 下午4:07 2018/8/7
*/
@Configuration
public class FeignConfig {
@Bean
Logger.Level feignLevel() {
return Logger.Level.FULL;
}
@Bean
FeignLoggerFactory infoFeignLoggerFactory() {
return new InfoFeignLoggerFactory();
}
}這樣就實現了自定義的日誌打印了，簡單吧，讓我們看看效果，是不是變成INFO日誌級別了。
2018-08-08 15:45:39.261 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] ---> POST http://localhost:8080/user HTTP/1.1
2018-08-08 15:45:39.262 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] Content-Type: application/json;charset=UTF-8
2018-08-08 15:45:39.262 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] Content-Length: 27
2018-08-08 15:45:39.262 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save]
2018-08-08 15:45:39.262 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] {"id":null,"name":"張三"}
2018-08-08 15:45:39.263 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] ---> END HTTP (27-byte body)
2018-08-08 15:45:39.691 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] <--- HTTP/1.1 200 (427ms)
2018-08-08 15:45:39.691 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] content-length: 0
2018-08-08 15:45:39.691 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] date: Wed, 08 Aug 2018 07:45:39 GMT
2018-08-08 15:45:39.691 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save]
2018-08-08 15:45:39.692 INFO 3514 --- [ main] com.example.feign.UserFeign : [UserFeign#save] <--- END HTTP (0-byte body)
細心的同學可能會發現，爲什麼我們的FeignLoggerFactory就起作用了，其實這是spring 強大的條件裝配功能
當FeignLoggerFactory不存在時才加載默認DefaultFeignLoggerFactory,如果對spring 條件裝配感興趣的同學可以看下官網，spring boot對spring條件裝配擴展了很多註解。
@Bean
@ConditionalOnMissingBean(FeignLoggerFactory.class)
public FeignLoggerFactory feignLoggerFactory() {
return new DefaultFeignLoggerFactory(logger);
}總結
此章節介紹了自定義Feign 日誌輸出，通過實現FeignLoggerFactory工廠類接口和繼承feign.Logger類，還使用了 slf4j日誌工具，在項目開發過程中建議使用slf4j這樣項目在更換日誌框架也不用修改源代碼了，擴展性更強。
樣例地址 spring-cloud-feign 分支 Spring-Cloud-Feign之日誌自定義擴展，
寫在最後
Spring Cloud Feign 系列持續更新中。。。。。歡迎關注
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