<%@ page import="org.apache.log4j.*" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head><title>Dynamic Log4J Control</title></head>
<body>
<h1>Dynamic Log4J Control</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">all known loggers</a>
</body>
</html>
原文：http://blog.csdn.net/statckoverflow/article/details/18913589