log 及 统计程序内存用量，时间

 private static final Logger log = Logger.getLogger(GAUD3040FlowHandler.class.getName());

 

         long mark = System.currentTimeMillis();
         log.info("writeDownloadExcel start memory used:"+(Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()));
         writeDownloadExcel();
   log.info("writeDownloadExcel finished memory used:"+(Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()));
   System.out.println("writeDownloadExcel Time expense:" + (System.currentTimeMillis() - mark));