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Spring Cloud Feign 之日志自定义扩展
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环境信息: java 1.8、Spring boot 1.5.10.RELEASE、spring cloud-Edgware.SR3、maven 3.3+
第二章 Spring Cloud Feign 之日志输出已经对Feign自带的日志输出说明，与外部HTTP接口交互时需要记录一些请求和响应日志来排查问题，虽然Feign支持但它的日志是Debug级别，并不符合我们在生产中使用INFO级别日志要求，所以这章介绍下自定义日志输出。
分析Spring Cloud Feign 默认日志
首先看下spring cloud feign 对日志输出的处理
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);
}
通过源码我们知道spring cloud feign 已经对feign的日志输出这块做了扩展，当然feign本身也可以，这里针对spring cloud feign 进行讲解。
FeignLoggerFactory是Feign日志工厂接口类，DefaultFeignLoggerFactory是它的默认实现，spring cloud feign 就是用的 DefaultFeignLoggerFactory
@Override
public Logger create(Class<?> type) {
return this.logger != null ? this.logger : new Slf4jLogger(type);
}
默认日志工厂使用Slf4jLogger日志，然后我们看下源码
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));
}
}
}
看到这里就知道为什么Spring Cloud Feign 日志输出的是Debug级别日志了。
自定Spring Cloud Feign日志输出
参考DefaultFeignLoggerFactory类实现自己的日志工厂实现类。
场景说明：将原有的debug级别，修改成info级别
第一步:实现FeignLoggerFactory工厂接口,InfoFeignLoggerFactory 是FeignConfig静态内部类
/**
* feign info 日志工厂
*/
public static class InfoFeignLoggerFactory implements FeignLoggerFactory {
@Override
public Logger create(Class<?> type) {
return new InfoFeignLogger(LoggerFactory.getLogger(type));
}
}
第二部: 继承feign.Logger实现info级别日志输出，InfoFeignLogger使用slf4j日志工具，此处只是简单的实现了info级别日志输出，如果想效率更高请参考Slf4jLogger添加一些日记级别判断
/**
* info feign 日志
* @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:日志工厂InfoFeignLoggerFactory注册到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();
}
}
这样就实现了自定义的日志打印了，简单吧，让我们看看效果，是不是变成INFO日志级别了。
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":"张三"}
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)
细心的同学可能会发现，为什么我们的FeignLoggerFactory就起作用了，其实这是spring 强大的条件装配功能
当FeignLoggerFactory不存在时才加载默认DefaultFeignLoggerFactory,如果对spring 条件装配感兴趣的同学可以看下官网，spring boot对spring条件装配扩展了很多注解。
@Bean
@ConditionalOnMissingBean(FeignLoggerFactory.class)
public FeignLoggerFactory feignLoggerFactory() {
return new DefaultFeignLoggerFactory(logger);
}
总结
此章节介绍了自定义Feign 日志输出，通过实现FeignLoggerFactory工厂类接口和继承feign.Logger类，还使用了 slf4j日志工具，在项目开发过程中建议使用slf4j这样项目在更换日志框架也不用修改源代码了，扩展性更强。
样例地址 spring-cloud-feign 分支 Spring-Cloud-Feign之日志自定义扩展，
写在最后
Spring Cloud Feign 系列持续更新中。。。。。欢迎关注
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