| 做一个产品或者项目，在测试时一般要打印详细的log，发布以后，因为打印有效率问题，所以通常将log4j级别设置为最高，以提高效率，一旦客户那里出了问题，要查看详细的日志信息才能确定，因此打印日志就是很重要的事情，但是让客户手工修改log4j配置文件，不是很好的事情。
修改log4j级别
public class Log4jConfig { public void enableInfo(String target){
LogManager.getLogger(target).setLevel(Level.INFO);
} public void enableWarn(String target){
LogManager.getLogger(target).setLevel(Level.WARN);
} public void enableError(String target){
LogManager.getLogger(target).setLevel(Level.ERROR) ;
} public void enableDebug(String target){
LogManager.getLogger(target).setLevel(Level.DEBUG) ;
} }
写个jsp可以很简单的做到，合理使用jstl <%@ page import="org.apache.log4j.*" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=GBK" language="java" %>
<html>
<head><title>Log4J级别控制</title></head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk" />
<body>
<h1>Log4J级别控制</h1>
<% String logName = request.getParameter("log");
if (null != logName) {
Logger log = ("".equals(logName) ?
Logger.getRootLogger() : Logger.getLogger(logName));
log.setLevel(Level.toLevel(request.getParameter("level"), Level.DEBUG));
}
%>
<c:set var="rootLogger" value="<%= Logger.getRootLogger() %>"/>
<form>
<table border="1">
<tr>
<th>Level</th>
<th>Logger</th>
<th>Set New Level</th>
</tr>
<tr>
<td>${rootLogger.level}</td>
<td>${rootLogger.name}</td>
<td>
<c:forTokens var="level" delims="," items="DEBUG,INFO,WARN,ERROR,OFF">
<a href="log4j.jsp?log=&level=${level}">${level}</a>
</c:forTokens>
</td>
</tr>
<c:forEach var="logger" items="${rootLogger.loggerRepository.currentLoggers}">
<c:if test="${!empty logger.level.syslogEquivalent || param.showAll}">
<tr>
<td>${logger.level}</td>
<td>${logger.name}</td>
<td>
<c:forTokens var="level" delims="," items="DEBUG,INFO,WARN,ERROR,OFF">
<a href="log4j.jsp?log=${logger.name}&level=${level}">${level}</a>
</c:forTokens>
</td>
</tr>
</c:if>
</c:forEach>
<tr>
<td></td>
<td><input type="text" name="log"/></td>
<td>
<select name="level">
<c:forTokens var="level" delims="," items="DEBUG,INFO,WARN,ERROR,OFF">
<option>${level}</option>
</c:forTokens>
</select> <input type="submit" value="Add New Logger"/></td>
</tr>
</table>
</form>
Show <a href="log4j.jsp?showAll=true">所有已知 loggers</a>
</body>
</html>
如果使用spring 2.0和jmx会很简单 [servletname]-servlet.xml配置
<bean id="exporter" class="org.springframework.jmx.export.MBeanExporter"> <property name="beans"> <map> <entry key="bean:name=logBean" value-ref="/hello.htm" /> </map> </property> </bean>
spring加入另外的两个配置
<entry key="bean:name=logBean" value-ref="logManager" /> <bean name="logManager" class="com.xx.Log4JManager"/>
写入
public class Log4JManager { public void setLogger(String packageName, String level) { LogManager.getLogger(packageName).setLevel(Level.toLevel(level)); } }
可以用JConsole 进行控制。 典型的log4j配置文件 # For JBoss: Avoid to setup Log4J outside $JBOSS_HOME/server/default/deploy/log4j.xml!
# For all other servers: Comment out the Log4J listener in web.xml to activate Log4J.
log4j.rootLogger=INFO,stdout,logfile log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - <%m>%n log4j.appender.logfile=org.apache.log4j.RollingFileAppender
log4j.appender.logfile.File=../../MgrWeb/log/mgrweb.log
log4j.appender.logfile.MaxFileSize=1024KB
# Keep three backup files.
log4j.appender.logfile.MaxBackupIndex=20
# Pattern to output: date priority [category] - message
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c\:%t\:%l] - %m%n
log4j.logger.org.hibernate.SQL=DEBUG
本blog的代码 没有发布在启明星辰的任何产品中 包括utm产品，请大家放心使用。
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