Connect Servlet to MySQL demo

package mao.servlets;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.DriverManager;
import java.sql.ResultSet;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import java.sql.*;

/**
 * Servlet implementation class TestAppXoSo
 */
@WebServlet("/TestAppXoSo")
public class TestAppXoSo extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestAppXoSo() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        PrintWriter writer = response.getWriter();
        writer.println("Thieu Mao was here <br>");
        response.setContentType("text/html;charset=UTF-8");
        String mao = request.getParameter("mao");
        writer.println("Mao = " + mao + "<br>");

        String db = "TestMySQL"; // Tên database
        String user = "root"; // Mặc định là root
        String pass = "admin"; // Mật khẩu quản trị MySQL
        try {
            // create our mysql database connection
            // String myDriver = "org.gjt.mm.mysql.Driver";
            // String myUrl = "jdbc:mysql://localhost/TestMySQL";
            // Class.forName(myDriver);
            // Connection conn = DriverManager.getConnection(myUrl,
            // "root","admin");
            String url = "jdbc:mysql://localhost/" + db + "?user=" + user
                    + "&password=" + pass;
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = (Connection) DriverManager.getConnection(url);

            // our SQL SELECT query.
            // if you only need a few columns, specify them by name instead of
            // using "*"
            String query = "SELECT * FROM user";

            // create the java statement
            Statement st = conn.createStatement();

            // execute the query, and get a java resultset
            ResultSet rs = st.executeQuery(query);

            // iterate through the java resultset
            while (rs.next()) {
                int id = rs.getInt("id");
                String username = rs.getString("username");
                String password = rs.getString("password");
                int level = rs.getInt("level");

                // print the results
                System.out.format("%s, %s, %s, %s\n", id, username, password,
                        level);
                writer.printf("%s, %s, %s, %s <br>\n", id, username, password,
                        level);
            }
            st.close();
        } catch (Exception e) {
            System.err.println("Got an exception! ");
            System.err.println(e.getMessage());
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

}