Load File Content and Save it back in a Servlet : File Save Read « Servlet « Java Tutorial

1. Java Tutorial
2. Servlet
3. File Save Read

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;

public class MyServlet  extends HttpServlet {

  int count;

  public void init() throws ServletException {
    FileReader fileReader = null;
    BufferedReader bufferedReader = null;
    try {
      fileReader = new FileReader("InitDestroyCounter.initial");
      bufferedReader = new BufferedReader(fileReader);
      String initial = bufferedReader.readLine();
      count = Integer.parseInt(initial);
      bufferedReader.close(); 
      return;
    }
    catch (Exception ignored) { }

    String initial = getInitParameter("initial");                    
    try {                                                            
      count = Integer.parseInt(initial);                             
      return;                                                        
    }                                                                
    catch (NumberFormatException ignored) { }  // null or non-integer value
    count = 0;                                                       
  }                                                                  
                                                                     
  public void doGet(HttpServletRequest req, HttpServletResponse res) 
                               throws ServletException, IOException {
    res.setContentType("text/plain");                                
    PrintWriter out = res.getWriter();                               
    count++;                                                         
    out.println("Since the beginning, this servlet has been accessed " +
                count + " times.");                                  
  }                                                                  
                                                                     
  public void destroy() {                                            
    super.destroy();
    saveState();                                                     
  }                                                                  
                                                                     
  public void saveState() {                                          
    FileWriter fileWriter = null;
    PrintWriter printWriter = null;
    try {                                                            
      fileWriter = new FileWriter("InitDestroyCounter.initial");
      printWriter = new PrintWriter(fileWriter);         
      printWriter.println(count);                                  
      printWriter.close();
      return;                                                        
    }                                                                
    catch (IOException e) {
    }
  }
}

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
    "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">

<web-app>
    <servlet><servlet-name>MyServletName</servlet-name>
             <servlet-class>MyServlet</servlet-class>
    </servlet>
    
    <servlet-mapping><servlet-name>MyServletName</servlet-name>
        <url-pattern>/index.html</url-pattern>
    </servlet-mapping>
</web-app>

25.20.File Save Read
	25.20.1.	Read File in a Servlet
	25.20.2.	Load File Content and Save it back in a Servlet