Read txt file whenever there are changes

Question

I have a problem in a project I’m doing, I need to do a program that reads a txt file and imports it to Mysql, I was able to do this part. But now I need this program to read this txt file whenever there are changes. And that matters to Mysql only the new data registered. Can anyone help me? Giving some study tips. Or some example. I’m starting now in java. Thank you.

package teste;

import java.io.*;   
import java.sql.*;   
import java.util.StringTokenizer;

class Teste{   
   public static void main(String args[]) {   
      try {   
         Class.forName("org.gjt.mm.mysql.Driver");   
         Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/Radius","root","admin");   
         Statement stm = con.createStatement();   
         BufferedReader reader = new BufferedReader(new FileReader("c:\\Users\\solutel\\Documents\\tabela\\tabela.txt"));

         String dados[] = new String[3];         
         String linha = reader.readLine();   
         while (linha != null) {   
            StringTokenizer st = new StringTokenizer(linha,";\"");   
            dados[0] = st.nextToken();   
            dados[1] = st.nextToken();   

            stm.executeUpdate("insert into radcheck (username,attribute,op,value) values ('"+dados[0]+"','" +"User-Password"+ "','"+ ":="+ "','"+dados[1]+"')");   
            linha = reader.readLine();         
         }   
      }   
      catch (Exception e) {   
         System.err.println("Erro: " + e.getMessage());   
      }   
   }   
}

Answer 1

I did a quick search and found this library that might be useful for what you need: Jnotify

EDIT:

I was interested in being something that I could use in the future both pure java and java/android...

So I did some tests and I’ll put here all the steps I did using the Jnotify to monitor a folder or file, Servant, Modified, Deleted or Renamed

Configuring

Extract from the file .zip the file .jar and the file with the name jnotify.dll for systems 32 bits and jnotify_64bit.dll for systems 64 bits

IN THE ECLIPSE - After creating the project add the library jar to the project example here, then add to dll following these steps:

1. Create a folder in the project with name dll
2. Put the file . dll inside
3. In the project -> properties -> Java Build Path -> tab: Source click on your/src project and expand
4. Click on Native library Location and then on the EDIT button next to it
5. Click the Workspace button and select the folder dll created in the first step.

IN NETBEANS - Add the .jar to the project as explained at that link, and for the part of dll i found the following steps:

1. Access the project properties
2. Click on RUN
3. In VM Options, please sort: -Djava.library.path="C: Directory where the DLL is from"

Code

This part has no mystery, I created a class only with the method main and what it needed as it already shows in the examples of the site itself Jnotify.

import net.contentobjects.jnotify.JNotify;
import net.contentobjects.jnotify.JNotifyListener;

public class Main {

      public static void main(String[] args) {

            try {
                  observarPasta();
            } catch (Exception e) {
                  e.printStackTrace();
            }
      }

      public static void observarPasta() throws Exception {

          // criei uma pasta temp para observar os arquivos que forem
          // criados e alterados dentro dela, mas pode ser alterado
          // para um arquivo especifico

          String path = "C:\\temp";

          // a mask é as ações que vão ser observadas, mas pode
          // ser utilizado JNotify.FILE_ANY para monitorar tudo
          // também.

          int mask = JNotify.FILE_CREATED  |
                     JNotify.FILE_DELETED  |
                     JNotify.FILE_MODIFIED |
                     JNotify.FILE_RENAMED;

          // monitorar subPastas?
          boolean watchSubtree = true;

          // adiciona o "MONITORADOR"
          int watchID = JNotify.addWatch(path, mask, watchSubtree, new Listener());

          //Fica esperando um tempo até terminar a aplicação
          //Dependendo da implementação da sua aplicação
          //isso não será necessário mas para esse teste é interessante
          Thread.sleep(1000000);

          // aqui remove o seu "MONITORADOR"
          boolean res = JNotify.removeWatch(watchID);

          if (!res) {
            // o id foi inválido.
          }
        }

          //essa implementação ja se explica com seus métodos
        static class Listener implements JNotifyListener {
          public void fileRenamed(int wd, String rootPath, String oldName, String newName) {
            print("renomeado " + rootPath + " : " + oldName + " -> " + newName);
          }

          public void fileModified(int wd, String rootPath, String name) {
            print("modificado " + rootPath + " : " + name);
          }

          public void fileDeleted(int wd, String rootPath, String name) {

            print("deletado " + rootPath + " : " + name);
          }

          public void fileCreated(int wd, String rootPath, String name) {

            print("criado " + rootPath + " : " + name);
          }

          void print(String msg) {
            System.err.println(msg);
          }
        }
}