Write.java Sample Code

// Copyright © 2001 by Apple Computer, Inc., All Rights Reserved.
//
// You may incorporate this Apple sample code into your own code
// without restriction. This Apple sample code has been provided "AS IS"
// and the responsibility for its operation is yours. You may redistribute
// this code, but you are not permitted to redistribute it as
// "Apple sample code" after having made changes.


package jblog;

import java.io.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
import java.net.URLEncoder;

/**
 * data recording servlet for
 * a very simple java web log
 *
 * @author Liz Warner
 */

public class Write extends HttpServlet {

    private MySQLConnector mydb = null;
    private PrintWriter out = null;

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
        throws IOException, ServletException
    {

        response.setContentType("text/html");
        out = response.getWriter();

        // write the HTML header
        out.println("<html><head><title>Java Web log</title></head>");
        out.println("<body bgcolor=\"white\">");

        // get the parameters "data" and "password" 
        // from the local environment (if they exist)
        String data = request.getParameter("data");
        String password = request.getParameter("password");
        if ( (data != null) && (password != null) )
        {
            //then the user has submitted an entry. call the writeData method 
            writeData(data,password);
        }
        else
        {
            // the user submitted either data or password, but not both   
            out.println("Missing data or password, please <a href=\"add_data.jsp\"> try again</a>.");
        }
        out.println("</body>");
        out.println("</html>");
    }

    public void doPost(HttpServletRequest request,
                       HttpServletResponse response)
        throws IOException, ServletException
    {
        // doPost just calls goGet 
        doGet(request,response);
    }

   // writeData checks for a valid password, 
   // and writes the log entry to the db table 
    private void writeData(String data, String password)
    {
        try
        {
           // create a new MySQLConnector object 
           mydb = new MySQLConnector();
           // get a valid Statement object from the connector 
           Statement stmt = mydb.connect();

            // first some really trivial security
            ResultSet rs = stmt.executeQuery("select count(*) as okay from blog_pass where password = \"" + password + "\"");
            if ( rs.next() && rs.getInt("okay") > 0 ) // trivial password checked out okay
            {
                // write the log entry 
                int written =  stmt.executeUpdate("insert into blog (data) values (\"" + data + "\")");
                out.println("Your entry was recorded. <br><br><br><a href=\"/blog/Show\"<View Entries</a>");
            }
            else
            {
                // bad password 
                // redirect the jsp entry form
                out.println("Bad password, please <a href=\"add_data.jsp?data=" + URLEncoder.encode(data) + "\">try again</a>.");
            }
            // disconnect from MySQL 
            mydb.disconnect(stmt);
        }
        catch (Exception ex)
        {
            out.println("Whoops, your entry was not recorded! <br><br> " + ex.toString() );
        }
    }
}