动态修改Log4J和Logback的日志级别

0、引言

Java项目开发调试或维护过程中，为方便问题快速定位，很多时候都会在代码中增加相关日志，但为了减少日志输出量，在生产环境通常都提高了日志的级别，导致生产环境出现问题时调试信息没有打印出来，排查定位问题比较困难。

那么，能否动态修改日志的级别？答案是肯定的。当出现问题时，动态降低日志级别，输出相关的调试信息；问题解决后，动态提高日志级别，屏蔽相关的调试信息。

1、实现过程

1.1 动态修改Log4J的日志级别

以下代码在 log4j 1.2.17 版本上验证通过

package controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Level;
import org.apache.log4j.LogManager;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * 动态修改j日志等级
 * @author [e-mail]
 * @date 2017年6月17日 上午12:13:18
 * @note Log4jController
 */
@Controller
@RequestMapping("/log4j")
public class Log4jController {
	@RequestMapping(value = "/root/{level}", method = RequestMethod.GET)
	@ResponseBody
	public String updateRootLog4jLevel(HttpServletRequest request, HttpServletResponse response, @PathVariable("level") String levelName) {
		Level level = Level.toLevel(levelName);
		LogManager.getRootLogger().setLevel(level);
		return "修改root的log4j{" + levelName + "}级别成功";
	}

	@RequestMapping(value = "/{package}/{level}", method = RequestMethod.GET)
	@ResponseBody
	public String updateLog4jLevel(HttpServletRequest request, HttpServletResponse response, @PathVariable("package") String packageName,
			@PathVariable("level") String levelName) {
		Level level = Level.toLevel(levelName);
		LogManager.getLogger(packageName).setLevel(level);
		return "修改package{" + packageName + "}的log4j{" + levelName + "}级别成功";
	}
}

1.2 动态修改Logback的日志级别

以下代码在 logback 1.2.3 版本上验证通过

package controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.LoggerContext;

/**
 * 动态修改logback日志级别
 * @author [e-mail]
 * @time 2020年4月7日 下午3:29:21
 * @since 1.0.0
 */
@Controller
@RequestMapping("/logback")
public class LogbackController {
	@RequestMapping(value = "/root/{level}", method = RequestMethod.GET)
	@ResponseBody
	public String updateRootLogbackLevel(HttpServletRequest request, HttpServletResponse response, @PathVariable("level") String levelName) {
		LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
		loggerContext.getLogger(Logger.ROOT_LOGGER_NAME).setLevel(Level.toLevel(levelName));
		return "修改root的logback{" + levelName + "}级别成功";
	}

	@RequestMapping(value = "/{package}/{level}", method = RequestMethod.GET)
	@ResponseBody
	public String updateLogbackLevel(HttpServletRequest request, HttpServletResponse response, @PathVariable("package") String packageName,
			@PathVariable("level") String levelName) {
		LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
		loggerContext.getLogger(packageName).setLevel(Level.toLevel(levelName));
		return "修改package{" + packageName + "}的logback{" + levelName + "}级别成功";
	}
}

2、验证

通过浏览器访问下面地址进行验证

## 修改log4j的root的日志级别
http://<ip>:<port>/<contextPath>/log4j/root/DEBUG
http://<ip>:<port>/<contextPath>/log4j/root/INFO
http://<ip>:<port>/<contextPath>/log4j/root/ERROR

## 修改log4j的org.apache包的日志级别
http://<ip>:<port>/<contextPath>/log4j/org.apache/DEBUG
http://<ip>:<port>/<contextPath>/log4j/org.apache/INFO
http://<ip>:<port>/<contextPath>/log4j/org.apache/ERROR

## 修改logback的root的日志级别
http://<ip>:<port>/<contextPath>/logback/root/DEBUG
http://<ip>:<port>/<contextPath>/logback/root/INFO
http://<ip>:<port>/<contextPath>/logback/root/ERROR

## 修改logback的org.apache包的日志级别
http://<ip>:<port>/<contextPath>/logback/org.apache/DEBUG
http://<ip>:<port>/<contextPath>/logback/org.apache/INFO
http://<ip>:<port>/<contextPath>/logback/org.apache/ERROR

3、参考资料

• springboot中动态修改logback日志级别
  https://www.cnblogs.com/heqiyoujing/p/9470752.html
• 动态修改日志级别小工具
  https://segmentfault.com/a/1190000013169276
• Spring Boot配置log4j记录日志
  https://blog.csdn.net/zzq900503/article/details/87629782