Program to access database using Servlet:
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/dbservlet")
public class DatabaseServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
public DatabaseServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
request.getRequestDispatcher("login.jsp").forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
PrintWriter out = response.getWriter();
response.setContentType("text/html");
String url = "jdbc:mysql://localhost/webdb1";
try {
String username = request.getParameter("username");
String password = request.getParameter("password");
Class.forName("com.mysql.cj.jdbc.Driver");
Connection con = DriverManager.getConnection(url, "root", "");
Statement stm = con.createStatement();
String sql = "select * from user1 where username = '"+username+"' and password = '"+password+"' ";
ResultSet rs = stm.executeQuery(sql);
if(!rs.next()){
out.println("<html><head><title>Login error</title></head><body>");
out.println("<br><hr>Unknown User<br><br>Access Denied</body></html>");
}
else {
out.println("<html><head><title>Login success</title></head><body>");
out.println("<br><br> Welcome " + username);
out.println("<br><hr><br><br>Authentication Success</body></html>");
}
rs.close();
stm.close();
con.close();
}
catch(SQLException e) {
e.printStackTrace();
}
catch(ClassNotFoundException e) {
e.printStackTrace();
}
}
}
`