spring_cloud_feign

本文主要是介绍spring_cloud_feign_log，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

这篇主要介绍一下spring cloud feign log的相关知识点。

下面以一个项目中的具体例子来说明：

下面是一个接口，在a服务中通过feign去调用b服务的generateBizNo接口，最后返回b服务的generateBizNo所返回的响应。

@FeignClient(value = "serviceName", url = "serviceUrl", fallbackFactory = FeignFallbackFactory.class,configuration = FeignLogConfiguration.class
)
public interface IOuterXXService extends BaseFeignClient {@RequestMapping(value = "/xx/yy", method = RequestMethod.POST)ResultBase<String> generateBizNo(XXX var1);
}

那么，如何来打印出这个feign调用的接口的相关日志呢？

使用log去该接口的实现类的方法调用开始和结束打印日志？
使用切面去打印日志？
还有其他？？？

这里我介绍的是使用spring cloud 的feign log来打印feign接口调用日志，效果图如下：

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通过上图我们可以看到feign log的日志输出有如下的信息：

接口调用的方法及域名
http协议
请求的头信息content-type以及content-length
入参报文和相应报文，都是json格式
请求耗时以及响应的状态码
请求应用的名称以及端口号

下面是关于spring cloud feign log的相关知识点和如何才可以做出上面的效果：

首先，需要增加一个配置类：

package com.xxx.xxx.xxx.spi.configuration;import feign.Logger;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;/*** @author lee* @date 2020/10/9***/
@Configuration
public class FeignLogConfiguration {@BeanLogger.Level feignLoggerLevel(){// 设置feign打印的log级别，此处的full代表的是信息全部打印，此log level非彼log levelreturn Logger.Level.FULL;}
}

第二步，在你使用@FeignClient的注解的时候，里面新增属性configuration=FeignLogConfiguration.class

@FeignClient(value = "serviceName", url = "serviceUrl", fallbackFactory = FeignFallbackFactory.class,configuration = FeignLogConfiguration.class
)

第三步，需要进行一些配置，我们使用的是nacos，所以在a服务的配置文件中新增如下的配置信息：

logging:level:com:xxx:yyy: DEBUG

需要注意的是logging和level两个层级是必须配置的，其他层级就是包路径，此处是日志的级别，需要设置为DEBUG，才可以生效。

到这里，基本就可以实现上面的效果了。

接下来说一下相关的知识点：

该Logger是feign包下的一个抽象类，位于

<dependency><groupId>io.github.openfeign</groupId><artifactId>feign-core</artifactId>
</dependency>

存在一个枚举Level，里面四个枚举项：

NONE:不打印日志
BASIC：只打印请求方法和url，以及响应状态码和执行时间
FULL：打印头信息，请求体，响应豹纹和元数据
HEADERS：打印基本的请求和响应头信息

其中存在一个logRequest的方法用来处理请求，logAndRebufferResponse来处理响应报文。

具体的源码如下所示：

package feign;import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.logging.FileHandler;
import java.util.logging.LogRecord;
import java.util.logging.SimpleFormatter;import static feign.Util.UTF_8;
import static feign.Util.decodeOrDefault;
import static feign.Util.valuesOrEmpty;/*** Simple logging abstraction for debug messages.  Adapted from {@code retrofit.RestAdapter.Log}.*/
public abstract class Logger {protected static String methodTag(String configKey) {return new StringBuilder().append('[').append(configKey.substring(0, configKey.indexOf('('))).append("] ").toString();}/*** Override to log requests and responses using your own implementation. Messages will be http* request and response text.** @param configKey value of {@link Feign#configKey(Class, java.lang.reflect.Method)}* @param format    {@link java.util.Formatter format string}* @param args      arguments applied to {@code format}*/protected abstract void log(String configKey, String format, Object... args);protected void logRequest(String configKey, Level logLevel, Request request) {log(configKey, "---> %s %s HTTP/1.1", request.method(), request.url());if (logLevel.ordinal() >= Level.HEADERS.ordinal()) {for (String field : request.headers().keySet()) {for (String value : valuesOrEmpty(request.headers(), field)) {log(configKey, "%s: %s", field, value);}}int bodyLength = 0;if (request.body() != null) {bodyLength = request.body().length;if (logLevel.ordinal() >= Level.FULL.ordinal()) {StringbodyText =request.charset() != null ? new String(request.body(), request.charset()) : null;log(configKey, ""); // CRLFlog(configKey, "%s", bodyText != null ? bodyText : "Binary data");}}log(configKey, "---> END HTTP (%s-byte body)", bodyLength);}}protected void logRetry(String configKey, Level logLevel) {log(configKey, "---> RETRYING");}protected Response logAndRebufferResponse(String configKey, Level logLevel, Response response,long elapsedTime) throws IOException {String reason = response.reason() != null && logLevel.compareTo(Level.NONE) > 0 ?" " + response.reason() : "";int status = response.status();log(configKey, "<--- HTTP/1.1 %s%s (%sms)", status, reason, elapsedTime);if (logLevel.ordinal() >= Level.HEADERS.ordinal()) {for (String field : response.headers().keySet()) {for (String value : valuesOrEmpty(response.headers(), field)) {log(configKey, "%s: %s", field, value);}}int bodyLength = 0;if (response.body() != null && !(status == 204 || status == 205)) {// HTTP 204 No Content "...response MUST NOT include a message-body"// HTTP 205 Reset Content "...response MUST NOT include an entity"if (logLevel.ordinal() >= Level.FULL.ordinal()) {log(configKey, ""); // CRLF}byte[] bodyData = Util.toByteArray(response.body().asInputStream());bodyLength = bodyData.length;if (logLevel.ordinal() >= Level.FULL.ordinal() && bodyLength > 0) {log(configKey, "%s", decodeOrDefault(bodyData, UTF_8, "Binary data"));}log(configKey, "<--- END HTTP (%s-byte body)", bodyLength);return response.toBuilder().body(bodyData).build();} else {log(configKey, "<--- END HTTP (%s-byte body)", bodyLength);}}return response;}protected IOException logIOException(String configKey, Level logLevel, IOException ioe, long elapsedTime) {log(configKey, "<--- ERROR %s: %s (%sms)", ioe.getClass().getSimpleName(), ioe.getMessage(),elapsedTime);if (logLevel.ordinal() >= Level.FULL.ordinal()) {StringWriter sw = new StringWriter();ioe.printStackTrace(new PrintWriter(sw));log(configKey, sw.toString());log(configKey, "<--- END ERROR");}return ioe;}/*** Controls the level of logging.*/public enum Level {/*** No logging.*/NONE,/*** Log only the request method and URL and the response status code and execution time.*/BASIC,/*** Log the basic information along with request and response headers.*/HEADERS,/*** Log the headers, body, and metadata for both requests and responses.*/FULL}/*** Logs to System.err.*/public static class ErrorLogger extends Logger {@Overrideprotected void log(String configKey, String format, Object... args) {System.err.printf(methodTag(configKey) + format + "%n", args);}}/*** Logs to the category {@link Logger} at {@link java.util.logging.Level#FINE}, if loggable.*/public static class JavaLogger extends Logger {final java.util.logging.Loggerlogger =java.util.logging.Logger.getLogger(Logger.class.getName());@Overrideprotected void logRequest(String configKey, Level logLevel, Request request) {if (logger.isLoggable(java.util.logging.Level.FINE)) {super.logRequest(configKey, logLevel, request);}}@Overrideprotected Response logAndRebufferResponse(String configKey, Level logLevel, Response response,long elapsedTime) throws IOException {if (logger.isLoggable(java.util.logging.Level.FINE)) {return super.logAndRebufferResponse(configKey, logLevel, response, elapsedTime);}return response;}@Overrideprotected void log(String configKey, String format, Object... args) {if (logger.isLoggable(java.util.logging.Level.FINE)) {logger.fine(String.format(methodTag(configKey) + format, args));}}/*** Helper that configures java.util.logging to sanely log messages at FINE level without additional* formatting.*/public JavaLogger appendToFile(String logfile) {logger.setLevel(java.util.logging.Level.FINE);try {FileHandler handler = new FileHandler(logfile, true);handler.setFormatter(new SimpleFormatter() {@Overridepublic String format(LogRecord record) {return String.format("%s%n", record.getMessage()); // NOPMD}});logger.addHandler(handler);} catch (IOException e) {throw new IllegalStateException("Could not add file handler.", e);}return this;}}public static class NoOpLogger extends Logger {@Overrideprotected void logRequest(String configKey, Level logLevel, Request request) {}@Overrideprotected Response logAndRebufferResponse(String configKey, Level logLevel, Response response,long elapsedTime) throws IOException {return response;}@Overrideprotected void log(String configKey, String format, Object... args) {}}
}

最后说一下整个的调用链路：

在这里插入图片描述