log4j --文件输出路径

利用占位符,然后再利用servlet给占位符赋值

log4j.rootLogger=debug,appender1
log4j.appender.appender1=org.apache.log4j.FileAppender 
log4j.appender.appender1.File=${path}/log/log.htm
log4j.appender.appender1.layout=org.apache.log4j.HTMLLayout

package com.hugui.flower.servlet;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
/**
 * 为log4j.properties文件中的占位符赋值，以便将日志信息输出到工程下
 * @author Administrator
 *
 */
public class Log4jInit extends HttpServlet {

	public void init(ServletConfig config) throws ServletException {
		String prefix = config.getServletContext().getRealPath("/");
		System.setProperty("path", prefix);
		
	}

}