📄 add.java
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/******************************************************************************************************************
IT03July Java Assignment
Message Board!
Created by Jason(632)
This program using JDBC to record user detail and using HTTP session to remember user infomations from HTML pages.
******************************************************************************************************************/
package myelf;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.text.*;
public class add extends HttpServlet
{
public void doPost (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
String url = "jdbc:hsqldb:" + getServletContext().getRealPath("/db/myDB");//link to the database
Statement statement;
ResultSet resultSet;
Connection connection;
HttpSession session;
session = request.getSession(false);//get user infomation from other java files
String username = (String)session.getValue("username");
String message = request.getParameter ("message");
try
{
Class.forName ("org.hsqldb.jdbcDriver");
connection = DriverManager.getConnection (url,"sa", "");
}
catch (ClassNotFoundException cnfex)
{
ErrorMessage (response, "Failed to load JDBC/ODBC driver.");
return;
}
catch (SQLException sqlex)
{
ErrorMessage (response, "Unable to connect to database.");
return;
}
try
{
PrintWriter output;//start to write the HTML files in java
response.setContentType ("text/html");
output = response.getWriter ();
output.println ("<html>");
output.println ("<head>");
output.println ("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=gb2312\">");
output.println ("<title>empty</title>");
output.println ("<style type=\"text/css\">");
output.println ("<!--");
output.println ("body {");
output.println ("background-color: #66CCFF;");
output.println ("margin-left: 10px;");
output.println ("margin-top: 10px;");
output.println ("margin-right: 10px;");
output.println ("margin-bottom: 10px;");
output.println ("}");
output.println (".style7 {font-family: Tahoma}");
output.println ("body,td,th {");
output.println ("font-family: Tahoma;");
output.println ("}");
output.println ("-->");
output.println ("</style></head>");
output.println ("<body>");
output.println ("<form name=\"form\" method=\"post\" action=\"http://www.myjavaserver.com/servlet/myelf.message\">");
if (checkMessage( message ))
{
statement = connection.createStatement ();
statement.executeUpdate ("INSERT INTO Message ( Username, Message,LeaveTime )Values ('" + username + "','" + message + "', Now());");
statement.close ();
output.println ("<table width=\"745\" border=\"0\" align=\"center\" cellpadding=\"0\" cellspacing=\"0\">");
output.println ("<tr>");
output.println ("<th width=\"139\" scope=\"col\"><img src=\"http://myjavaserver.com/~myelf/pic/logo.jpg\" width=\"139\" height=\"82\"></th>");
output.println ("<th width=\"318\" class=\"style7\" scope=\"col\"> </th>");
output.println ("<th width=\"45\" scope=\"col\"> </th>");
output.println ("<th width=\"59\" valign=\"baseline\" scope=\"col\"></span></th>");
output.println ("<th width=\"103\" valign=\"baseline\" scope=\"col\"><span class=\"style7\"><a href=\"http://www.myjavaserver.com/servlet/myelf.logout\">Logout</a></span></th>");
output.println ("<th width=\"81\" valign=\"baseline\" scope=\"col\"><span class=\"style7\"><a href=\"http://myjavaserver.com/~myelf/search.html\">Search</a></span></th>");
output.println ("</tr>");
output.println ("</table>");
output.println ("<table width=\"746\" height=\"65\" border=\"0\" align=\"center\" cellpadding=\"0\" cellspacing=\"0\">");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"><div align=\"left\">Thank you, " + username + " ! Your message was relased. ");
output.println ("in the board! </div></th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"><div align=\"left\">Click <a href=javascript:history.back()><em>Here</em></a> ");
output.println ("to leave a new message again! </div></th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr> ");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"><div align=\"left\"><input name=\"Submit\" type=\"submit\" class=\"style7\" value=\"Back TO THE MESSAGE BOARD\"></div></th>");
output.println ("</tr>");
output.println ("</table>");
output.println ("<p> </p>");
output.println ("<p> </p>");
output.println ("<p> </p>");
output.println ("<p> </p>");
output.println ("</form>");
output.println ("</body>");
output.println ("</html>");
output.close ();
}
else
{
output.println ("<table width=\"745\" border=\"0\" align=\"center\" cellpadding=\"0\" cellspacing=\"0\">");
output.println ("<tr>");
output.println ("<th width=\"139\" scope=\"col\"><img src=\"http://myjavaserver.com/~myelf/pic/logo.jpg\" width=\"139\" height=\"82\"></th>");
output.println ("<th width=\"318\" class=\"style7\" scope=\"col\"> </th>");
output.println ("<th width=\"45\" scope=\"col\"> </th>");
output.println ("<th width=\"103\" valign=\"baseline\" scope=\"col\"><span class=\"style7\"><a href=\"http://www.myjavaserver.com/servlet/myelf.logout\">Logout</a></span></th>");
output.println ("<th width=\"81\" valign=\"baseline\" scope=\"col\"><span class=\"style7\"><a href=\"http://myjavaserver.com/~myelf/search.html\">Search</a></span></th>");
output.println ("</tr>");
output.println ("</table>");
output.println ("<table width=\"746\" height=\"65\" border=\"0\" align=\"center\" cellpadding=\"0\" cellspacing=\"0\">");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"><div align=\"left\">Sorry " + username + ", you didn't leave any message ");
output.println ("in the board! </div></th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"><div align=\"left\">Click <a href=javascript:history.back()><em>Here</em></a> ");
output.println ("to leave a new message again! </div></th>");
output.println ("</tr>");
output.println ("<tr>");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr> ");
output.println ("<th scope=\"col\"> </th>");
output.println ("</tr>");
output.println ("<tr> ");
output.println ("<th scope=\"col\"><div align=\"left\"><input name=\"Submit\" type=\"submit\" class=\"style7\" value=\"Back TO THE MESSAGE BOARD\"></div></th>");
output.println ("</tr>");
output.println ("</table>");
output.println ("<p> </p>");
output.println ("<p> </p>");
output.println ("<p> </p>");
output.println ("<p> </p>");
output.println ("</form>");
output.println ("</body>");
output.println ("</html>");
output.close ();
}
}
catch (SQLException sqlex)
{
ErrorMessage (response, sqlex.getMessage());
}
try
{
connection.close ();
}
catch (SQLException sqlex)
{
// Cannot send error message, so just exit
}
}
public void ErrorMessage (HttpServletResponse response, String message)//Error message
throws ServletException, IOException
{
PrintWriter output;
response.setContentType ("text/html");
output = response.getWriter ();
output.println ("<HTML><HEAD><TITLE>Error</TITLE></HEAD><BODY>");
output.println ("<H1>Error</H1>" + message + "</BODY></HTML>");
output.close ();
}
private boolean checkMessage ( String message )//determaine user input is null or not
{
if ( message.equals(""))
return false;
else
return true;
}
}
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