I was trying to connect mysql database in my servlet. Then I'm getting an exception.
But when I am testing the database connection from a usual Java class the connection is ok and I getting the data from the database.
The exception I'm getting on tomcat server console is:
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver .
The code of my DatabaseHandler.java is:
import java.sql.*;
public class DatabaseHandler {
private Statement stmt;
private Connection con;
String username = "root";
String password = "thunder";
String dbname = "bidderboy";
public DatabaseHandler()
{
this.createConnection();
}
private void createConnection()
{
//create the connection for first time
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
con = DriverManager.getConnection("jdbc:mysql://localhost/"+dbname , username , password);
stmt = con.createStatement();
} catch (Exception ex) {
System.out.println(ex.toString());
}
}
public int executeUpdate(String sql)
{
int result = 0;
//before update checks if connection is open
try {
if(con.isClosed()) {
Class.forName("com.mysql.jdbc.Driver").newInstance();
con = DriverManager.getConnection("jdbc:mysql://localhost/"+dbname , username , password);
stmt = con.createStatement();
}
} catch (Exception ex) {
System.out.println(ex.toString());
}
//try to executeUpdate the sql command
try{
result = stmt.executeUpdate(sql);
}
catch(Exception ex){
System.out.println("Couldn't executeUpdate sql command");
}
return result;
}
public ResultSet executeQuery(String sql)
{
ResultSet rs = null;
//before Query checks if connection is open
try {
if(con.isClosed()) {
Class.forName("com.mysql.jdbc.Driver").newInstance();
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/"+dbname , username , password);
stmt = con.createStatement();
}
} catch (Exception ex) {
System.out.println(ex.toString());
}
//try to executeQuery the sql command
try{
rs = stmt.executeQuery(sql);
}
catch(Exception ex){
System.out.println("Couldn't executeQuery sql command");
}
return rs;
}
public void closeConnection()
{
//if connection is open try to close the connection
try {
if(!con.isClosed()) {
con.close();
}
} catch (SQLException ex) {
System.out.println("Failed to close database connection");
}
}
}
The code of my servlet is:
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@SuppressWarnings("serial")
public class UserLogin extends HttpServlet{
public UserLogin()
{
}
@Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
DatabaseHandler dbh = new DatabaseHandler();
String username="mamun";
String password="1234";
String dbusername="";
String dbpassword="";
String sql = "select * from users where username='"+username+"' and password='"+password+"'";
ResultSet rs = dbh.executeQuery(sql);
try {
while(rs.next())
{
dbusername = rs.getNString(1);
dbpassword = rs.getNString(2);
}
} catch (SQLException e) {}
System.out.println(dbusername+" "+dbpassword);
}
}
And the Code of normal java class from which I'm getting my data is:
import java.sql.ResultSet;
import java.sql.SQLException;
public class DatabaseConnectionTest {
public static void main(String[] args) {
String sql = "Select * from users";
DatabaseHandler dbh = new DatabaseHandler();
ResultSet rs = dbh.executeQuery(sql);
try {
while(rs.next())
{
String n = rs.getNString(1);
String c = rs.getNString(2);
System.out.println("Name: "+n+" Contact: "+c);
}
} catch (SQLException ex) {
System.out.println(ex.toString());
}
}
}
Anybody please explain why I'm getting this class not found exception and What can be the solution. Thanks in advance.
