1）log4j.properties文件内容如下，此文件要配置到ClassPath中去。
log4j.rootLogger=debug, stdout, R
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%d %5p [%t] (%F:%L) - %m%n
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=AccountBook.log
log4j.appender.R.MaxFileSize=1000KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=1
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%d %5p [%t] (%F:%L) - %m%n
2）书写一个初始化Log4j的servlet如下：
public class Log4jInit extends HttpServlet {
private static final long serialVersionUID = -4499302208753939187L;
static Logger logger = Logger.getLogger(Log4jInit.class);
public void init(ServletConfig config) throws ServletException {
String prefix = config.getServletContext().getRealPath("/");
String file = config.getInitParameter("log4j");
String filePath = prefix + file;
Properties props = new Properties();
try {
FileInputStream istream = new FileInputStream(filePath);
props.load(istream);
istream.close();
String logFile = prefix + props.getProperty("log4j.appender.R.File");//设置路径
props.setProperty("log4j.appender.R.File",logFile);
// 装入log4j配置信息
PropertyConfigurator.configure(props);
} catch (IOException e) {
System.out.println("Could not read configuration file [" + filePath + "].");
System.out.println("Ignoring configuration file [" + filePath + "].");
return;
}
}
}
3）在Web.xml中配置Log4jInit如下：
<servlet>
<servlet-name>log4j-init</servlet-name>
<servlet-class>
com.sitinspring.action.Log4jInit
</servlet-class>
<init-param>
<param-name>log4j</param-name>
<param-value>WEB-INF/classes/log4j.properties</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
此后配置文件就出现在工程目录下。