Servlet Question

"elaineskytta" <[email protected]> Wed, 05 Jan 2005 21:41:42 -0000
Newsgroups	gmane.comp.java.advanced-servlets
Message-ID	<[email protected]>

Hi,

I wrote a servlet that handles MySQL stuff.  It works PERFECTLY when I
call it from a MAIN routine.  It inserts a record into the MYSQL 
database.

Then when I call it from another servlet, to build a webpage it does
not work. I added some debug to it and it does not find the mysql
driver.  The web page comes up with the debug displayed.

What am I doing wrong?  Why does it work from a stand alone program
but not from another servlet?

I am attaching my main (xTest.java), and my two servlets (Test.java)
and (MySQLUtilities.java)

Thanks for any light you can shed on the situation.

Elaine
------------------------------------------------------------------------------------------
File: xTest.java (WORKS with MySQLUtilities.java)
public class xTest
{
	/* This sample program calls the insertUser method and inserts 
	the record into the database. */
	/* It works correctly. */
	public static void main ( String args[] ) throws Exception 
	{

		Integer UserId;
		String Login; 
		String Password; 
		String FirstName; 
		String LastName; 
		String eMail; 
		String Phone;

		UserId = 1;
		Login = "xxx";
		Password = "x";
		FirstName = "xxx";
		LastName = "xxx";
		eMail = "[email protected]";
		Phone = "123-456-7890";

		String xxx = new MySQLUtilities().insertUser(UserId, Login,
Password, FirstName, LastName, eMail, Phone);

		System.out.println (xxx );

	}
}
----------------------------------------------------------------------------------------------
File: Test.java (Do NOT work with MySQLUtilities.java)

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

public class Test extends HttpServlet
{
	/* This sample servlet calls the insertUser method.  InsertUser does
	not find  the database driver. */
	/* WHY - The exact same code works when called from the Main program. */
	public void doGet(HttpServletRequest request, 
		HttpServletResponse response)
	throws IOException, ServletException
	{
		Integer UserId;
		String Login; 
		String Password; 
		String FirstName; 
		String LastName; 
		String eMail; 
		String Phone;

		String PageTitle = "Testing MySQL Connection";

		String PageHeader = "<HTML>\n" +
			"<HEAD>\n" +
			"<title>" + PageTitle + "</title>\n" +
			"</head>\n" +
			"<body>\n" +
			"<h1>" +  PageTitle + "</h1>";

		String PageFooter = "</body>\n" +
			"</html>\n";

		String strDebug = "";

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

		UserId = 2;
		Login = "yyy";
		Password = "y";
		FirstName = "yyy";
		LastName = "yyy";
		eMail = "[email protected]";
		Phone = "321-321-4321";

  		strDebug = new MySQLUtilities().insertUser(UserId, Login,
Password, FirstName, LastName, eMail, Phone);

		out.println(PageHeader + strDebug + PageFooter);

	}
}
-------------------------------------------
File: MySQLUtilities.java
 
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

/* This code works correctly when called from Main.  The mysql driver
is found and
the data is inserted into the database.  When called from the "Test"
servlet the 
mysql driver is not found. WHY? */
public class MySQLUtilities extends HttpServlet
{
	private static String strDebug = "";

	private static String host = "localhost";
	private static String database = "elearning";

/***********************************************************************
	 *
	 *  Opens the connection to the MySQL database
	 *
	 
	***********************************************************************/
	protected Connection openConnection ( String host, String database )
	throws Exception
	{
    
		try 
		{
			strDebug = strDebug + " Before Class.forName ";
			Class.forName ( "org.gjt.mm.mysql.Driver" );
			strDebug = strDebug + " After Class.forName ";

			System.out.println ( "MySQL Driver Found" );
		} 
		catch ( java.lang.ClassNotFoundException e ) 
		{
			System.out.println("MySQL JDBC Driver not found ... ");
			strDebug = strDebug + " MySQL JDBC Driver not found ...  ";

			throw ( e );
		}

    		String url = "";
	    	try 
		{
	    		url = "jdbc:mysql://" + host + "/" + database;

      		Connection con = DriverManager.getConnection(url);
			System.out.println("Connection established to " + url + "...");
		    
			return con;
    		} 
		catch ( java.sql.SQLException e ) 
		{
			System.out.println("Connection couldn't be established to " + url);
			throw ( e );
    		}
	}

/***********************************************************************
	 *
	 *  Closes the connection to the MySQL database
	 *
	 
	***********************************************************************/
	protected void closeConnection (Connection con)
	throws Exception
	{
		try 
		{
			/* Close the connection */    
			con.close();
		}
		catch ( SQLException e ) 
		{
			System.out.println("Exception in closeConnection");
			throw(e);
		}

	}

/***********************************************************************
     	 *  This method executes an SQL statement
     	 *  @param con - database connection
     	 *  @param sqlStatement - to be executed (create, insert,
update, drop)
	 
	***********************************************************************/
	protected void executeSQL ( Connection con, String sqlStatement )
          throws Exception 
	{    
		try 
		{
			Statement s = con.createStatement ( );
			s.execute ( sqlStatement );      		
			s.close ( );
		} 
		catch ( SQLException e ) 
		{
			System.out.println ( "Error executing sql statement" );
			throw ( e );
		}
	}

/***********************************************************************
	 This function will insert one record into the User table
	 
	***********************************************************************/
	public String insertUser (Integer UserId, String Login, String 
Password, 
		String FirstName, String LastName, String eMail, String Phone)
	{		

		try 
		{
			String sqlStr;
			sqlStr = "insert into User (UserId, Login, Password, FirstName,
LastName, eMail, Phone) values (";
			sqlStr = sqlStr + UserId.toString() + ", '" + Login + "', '" +
Password + "', '" + FirstName + "', '" +
				LastName + "', '" + eMail + "', '" +  Phone + "')";

strDebug = strDebug + "Before openConnection ";

		  	/* Open connection to the database */
		      Connection con = openConnection (host, database);

strDebug = strDebug + "After openConnection ";

			/* Insert the User record into the database. */
			executeSQL (con, sqlStr);

			/* Close the database */
		      closeConnection (con );
		} 
		catch ( Exception e ) 
		{
			System.out.println("Exception in Insert User\n");
		}

		return(strDebug);
	}
}






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