package com.vogella.web.filecounter.dao;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

public class FileDao {

    public int getCount() {
        int count = 0;
        // Load the file with the counter
        FileReader fileReader = null;
        BufferedReader bufferedReader = null;
        PrintWriter writer = null;
        try {
            File f = new File("FileCounter.initial");
            if (!f.exists()) {
                f.createNewFile();
                writer = new PrintWriter(new FileWriter(f));
                writer.println(0);
            }
            if (writer != null) {
                writer.close();
            }

            fileReader = new FileReader(f);
            bufferedReader = new BufferedReader(fileReader);
            String initial = bufferedReader.readLine();
            count = Integer.parseInt(initial);
        } catch (Exception ex) {
            if (writer != null) {
                writer.close();
            }
        }
        if (bufferedReader != null) {
            try {
                bufferedReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return count;
    }

    public void save(int count) throws Exception {
        FileWriter fileWriter = null;
        PrintWriter printWriter = null;
        fileWriter = new FileWriter("FileCounter.initial");
        printWriter = new PrintWriter(fileWriter);
        printWriter.println(count);

        // make sure to close the file
        if (printWriter != null) {
            printWriter.close();
        }
    }
}

package com.vogella.web.filecounter.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.vogella.web.filecounter.dao.FileDao;

/**
 * Servlet implementation class FileCounter
 */
@WebServlet("/FileCounter")
public class FileCounter extends HttpServlet {
    private static final long serialVersionUID = 1L;

    int count;
    private FileDao dao;

    @Override
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // Set a cookie for the user, so that the counter does not increate
        // every time the user press refresh
        HttpSession session = request.getSession(true);
        // Set the session valid for 5 secs
        session.setMaxInactiveInterval(5);
        response.setContentType("text/plain");
        PrintWriter out = response.getWriter();
        if (session.isNew()) {
            count++;
        }
        out.println("This site has been accessed " + count + " times.");
    }

    
    @Override
    public void init() throws ServletException {
        dao = new FileDao();
        try {
            count = dao.getCount();
        } catch (Exception e) {
            getServletContext().log("An exception occurred in FileCounter", e);
            throw new ServletException("An exception occurred in FileCounter"
                    + e.getMessage());
        }
    }
    
    public void destroy() {
        super.destroy();
        try {
            dao.save(count);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}