log4j 配置日志文件，把日志信息输出到项目的某个文件夹下

package com.chen.initServlet; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.util.Properties; 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.Logger; import org.apache.log4j.PropertyConfigurator; public class Log4jServlet extends HttpServlet { @Override public void init() throws ServletException { Logger log = Logger.getLogger(Log4jServlet.class); String path = this.getServletContext().getRealPath("/"); String log4j_name = getInitParameter("log4j_name");//获取配置文件 log4j.properties String log4j_save = getInitParameter("log4j_save");//获取生成日志文件保存地址 if(log4j_save==null) { log4j_save="mylog.log"; } String src = path+"WEB-INF"+File.separator+"classes"+ File.separator + log4j_name; Properties props = new Properties(); try { FileInputStream log4jStream = new FileInputStream(src); //通过流的方式读取信息 props.load(log4jStream); log4jStream.close(); //设置保存路径 String logFile = path+log4j_save; props.setProperty("log4j.appender.R.File", logFile); //设置保存路径 System.out.println("log4j_src = "+src); if(log4j_name!=null) { PropertyConfigurator.configure(props); //装入log4j配置信息 }else{ BasicConfigurator.configure(); } }catch(Exception e) { log.error("装载文件出错"); }finally { super.init(); } } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); } public static void main(String[] args) { System.out.println("aa"); } }