import java.io.File;
import java.io.IOException;import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.PropertyConfigurator;public class Log4JInitServlet extends HttpServlet {private static final long serialVersionUID = 1L;public Log4JInitServlet() {super();}public void init(ServletConfig config) throws ServletException {System.out.println("正在初始化 log4j日志设置信息");String log4jLocation = config.getInitParameter("log4j-properties-location");ServletContext sc = config.getServletContext();if (log4jLocation == null) {System.err.println("没有找到log4j-properties-location, 所以使用 BasicConfigurator初始化");BasicConfigurator.configure();} else {String webAppPath = sc.getRealPath("/");String log4jProp = webAppPath + log4jLocation;File yoMamaYesThisSaysYoMama = new File(log4jProp);if (yoMamaYesThisSaysYoMama.exists()) {System.out.println(log4jProp + "初始化日志设置信息");PropertyConfigurator.configure(log4jProp);} else {System.err.println(log4jProp+ " 文件没有找到， 所以使用 BasicConfigurator初始化");BasicConfigurator.configure();}}super.init(config);}protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {}protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {}}

<servlet><servlet-name>Log4JInitServlet</servlet-name><servlet-class>com.scme.filter.Log4JInitServlet</servlet-class><init-param><param-name>log4j-properties-location</param-name><param-value>/WEB-INF/log4j.properties</param-value></init-param><load-on-startup>1</load-on-startup> <!-- 设置加载顺序--></servlet>

log4j.rootLogger = INFO,stdout,D log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out  //设置为控制台输出，级别为默认的INFO
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH\:mm\:ss,SSS} method\:%l%n%m%n  log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File =../jump_log/logs.log  //输出到文件
log4j.appender.D.DatePattern ='_'yyyy-WW'.log'  //每周产生一个新文件
log4j.appender.D.Append = true
log4j.appender.D.Encoding=UTF-8  //设置日志文件编码
log4j.appender.D.Threshold = INFO
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern =%-d{yyyy-MM-dd HH\:mm\:ss}  [ %t\:%r ] - [ %p ]  %m%n 

 　 %m   输出代码中指定的消息%p   输出优先级，即DEBUG，INFO，WARN，ERROR，FATAL %r   输出自应用启动到输出该log信息耗费的毫秒数 %c   输出所属的类目，通常就是所在类的全名 %t   输出产生该日志事件的线程名 %n   输出一个回车换行符，Windows平台为“\r\n”，Unix平台为“\n” %d   输出日志时间点的日期或时间，默认格式为ISO8601，也可以在其后指定格式，比如：%d{yyy MMM dd HH:mm:ss , SSS}，输出类似：2002年10月18日 22 ： 10 ： 28 ， 921 %l   输出日志事件的发生位置，包括类目名、发生的线程，以及在代码中的行数。举例：Testlog4.main(TestLog4.java: 10 )