Java Web动态配置log4j

导入log4j的jar包，

在web.xml中做如下配置

　　<!-- Log4j Configuration -->
    <context-param>
        <param-name>webAppRootKey</param-name>
        <param-value>myapplication.root</param-value>
    </context-param>
    <context-param>
        <param-name>log4jConfigLocation</param-name>
        <param-value>/WEB-INF/log4j.properties</param-value>
    </context-param>
    <context-param>
        <param-name>log4jRefreshInterval</param-name>
        <param-value>60000</param-value><!-- 重新加载log4j配置的间隔时间 ms -->
    </context-param>

在WEB-INF下建立文件log4j.properties

内容如下

log4j.rootLogger=INFO, stdout, logfile

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

log4j.appender.logfile=org.apache.log4j.RollingFileAppender
log4j.appender.logfile.File=${user.home}/myapplication.log
log4j.appender.logfile.MaxFileSize=512KB
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

可根据不同的需求进行不同的配置。

在web页面上做个选择logging level的页面，选择logging level，传入servlet，

　　
　　//查询logging level，并传到web页面
　　@RequestMapping(value="/logging_view", method = RequestMethod.GET)
    public String toLoggingView(HttpServletRequest request,Model model){
        Properties props = new Properties();
        try {
　　　　　　　//读取log4j.properties文件的内容
            String path = SystemController.class.getClassLoader().getResource("").toURI().getPath();
            InputStream in = new BufferedInputStream(new FileInputStream(
                    path+"../log4j.properties"));//这个是log4j.properties的文件路径，根据自己的servlet的path自行配置
            props.load(in);
            String value = props.getProperty("log4j.rootLogger");
            logger.debug("log4j.rootLogger键的值是："+ value);
            model.addAttribute("rootLogger", value);
            in.close();
        } catch (URISyntaxException e) {
            logger.error("SystemController : logging_view : URISyntaxException:"+e);
        } catch (FileNotFoundException e) {
            logger.error("SystemController : logging_view : FileNotFoundException:"+e);
        } catch (IOException e) {
            logger.error("SystemController : logging_view : IOException:"+e);
        }
        return SessionHandler.verifySession(request, "logging_view");
    }
    //获取web页面传的数据，设置logging level
    @RequestMapping(value="/setLoggingLevel", method = RequestMethod.POST)
    public String setLoggingLevel(@RequestParam String rootLogger, @RequestParam String loggerLevel,
            HttpServletRequest request, Model model){
        RequestContext requestContext = new RequestContext(request);
        String[] loggers = rootLogger.split(",");
        loggers[0] = loggerLevel;
        String logging = "";
        for(int i = 0; i < loggers.length; i++){
            logging += loggers[i]+",";
        }
        logging = logging.substring(0, logging.length()-1);
        Properties props = new Properties();
        try {
　　　　　　　//将logging level写入log4j.properties文件
            String path = SystemController.class.getClassLoader().getResource("").toURI().getPath()+"../log4j.properties";
            InputStream in = new BufferedInputStream(new FileInputStream(
                    path));
            props.load(in);
            OutputStream fos = new FileOutputStream(path);
            props.setProperty("log4j.rootLogger", logging);
            props.store(fos,"last update");
            String value = props.getProperty("log4j.rootLogger");
            logger.debug(value);
            //关闭文件
            in.close();
            fos.close();
            List<String> list = new ArrayList<String>();
            list.add(requestContext.getMessage("logging.level"));
            if(value.split(",")[0].equals(loggerLevel)){
                model.addAttribute("msg", requestContext.getMessage("edit.success",list));
            }else{
                model.addAttribute("msg", requestContext.getMessage("edit.failed",list));
            }
        } catch (URISyntaxException e) {
            logger.error("SystemController : logging_view : URISyntaxException:"+e);
        } catch (FileNotFoundException e) {
            logger.error("SystemController : logging_view : FileNotFoundException:"+e);
        } catch (IOException e) {
            logger.error("SystemController : logging_view : IOException:"+e);
        }
        return "msg";
    }

这样就完成了，log4j的其他配置，一样按照上面的方法做就行。