Use Java to implement logging utility class sharing

package com.teligen.eos.teleCode;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Date;

public class WriteLogUtil {
 private static String rootPath = "D:\logs\";

 
 public static void writeMsgToFile(String msg) {
  //Delete the previous file
  delOldFile();

  FileWriter fileWriter = null;
  try {
   fileWriter = new FileWriter(getFileName(),true);
   Date today = new Date();
   String time = String.valueOf(today.getHours()) + ":" + String.valueOf(today.getMinutes()) + " " + String.valueOf(today.getSeconds());
   fileWriter.write("#" + time + "# [" + msg + "]" + "rn");
   fileWriter.flush();
  } catch (IOException e) {
   System.out.println("###  Write log to file exception  ### >>> " + e.getMessage());
   e.printStackTrace();
  } finally {
   try {
    fileWriter.close();
   } catch (IOException e) {
    System.out.println("###  Turn off logging stream exceptions  ### >>> " + e.getMessage());
    e.printStackTrace();
   }
  }
 }

 
 private static void delOldFile() {
  Date today = new Date();
  int month = today.getMonth()+1;
  month = month - 2;
  if(month == -1) month = 11;
  if(month == 0) month = 12;
  String delPath = rootPath + String.valueOf(month) + "\";
  File folder = new File(delPath);
  if(folder.exists()) {
   File[] files = folder.listFiles();
   for(int i=0; i<files.length; i++) {
    files[i].delete();
   }
  }
 }

 
 private static String getFileName() {
  Date today = new Date();
  String fileName = String.valueOf((today.getYear()+1900)) + String.valueOf((today.getMonth()+1)) + String.valueOf(today.getDate()) + ".log";

  
  //Create a directory
  File folder = new File(rootPath + String.valueOf((today.getMonth()+1)) + "\");
  if(!folder.exists()) {
   folder.mkdirs();
  }
  //Create a file
  File file = new File(fileName);
  if(!file.exists()) {
   try {
    file.createNewFile();
   } catch (IOException e) {
    System.out.println("###  New log file exception  ### >>> " + e.getMessage());
    e.printStackTrace();
   }
  }

  fileName = rootPath + String.valueOf((today.getMonth()+1)) + "\" + fileName;

  return fileName;
 }

 
 public static void main(String[] args) {
  //getFileName();
  String testString = " Keep a journal: 71FABB7890D2CC0D267FBD84F409618C0303BC597B9244C324947BDE4B1C0B4CB08C33FC461F7BADD088535DAE42D8D7D06F4134E442D9D1CE3A0F9B3EDD64337A2D18CE34FCDC137B7CBD84F409618C03038FEAEC79F79C2F58BD84F409618C03038FEAEC79F79C2F58BD84F409618C03038FEAEC79F79C2F581790ACB3C178641D14D8C09905BC52CF1C8249B12F2EDE5AC3C8FAF2FD8A686E";
  writeMsgToFile(testString);
  //delOldFile();
 }
}