DAO backend to Authentication/Authorization filters

package daos;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MerUsersDAO {

    private static final String DBCONSTRING = "jdbc:mysql://localhost:3306/merwebappdb";
    private static final String DBUSER = "root";
    private static final String DBPASSWORD="censored";

    private static final String GETUSERSTATEMENT="SELECT COUNT(*) FROM registered_users WHERE userid=? AND password=?";
    private static final String GETPERMSSTATEMENT="SELECT COUNT(*) FROM pageperms WHERE pageurl=? AND userid=?";
    public MerUsersDAO() {
    try {
        Class.forName("com.mysql.jdbc.Driver");
    } catch (ClassNotFoundException e) {
        System.err.println("Couldn't load mysql driver.");
    }


    }
    /**Check to see if a given user is a valid user, with the correct password.
     * This is a login verifier, and should be used with the AUTHENTICATION FILTER.
     * @param username
     * @param password
     * @return true if valid user; false otherwise
     * @throws Exception if database contains more than one user with this username/password
     */
    public boolean isUserValid(String username, String password) throws DBIntegrityException{

    try(Connection conn=DriverManager.getConnection(DBCONSTRING,DBUSER,DBPASSWORD);
        PreparedStatement userRecStmt=conn.prepareStatement(GETUSERSTATEMENT))
    {
        userRecStmt.setString(1,username);
        userRecStmt.setString(2,password);
        ResultSet userCount = userRecStmt.executeQuery();  //this is a count bc the sql was SELECT COUNT(*) FROM..
        if(userCount.next()) //first item, only entry should be the count of matching records
        {   int matchingCount  = userCount.getInt(1);
            System.out.printf("Found %d user(s) matching the username %s and password %s.%n",matchingCount,username,password);
            if(matchingCount==1) //should match exactly 1
                return true;
            else if(matchingCount>1)
                throw new DBIntegrityException(String.format("Found more than one (%d) user(s) matching the username %s and password %s.%n"
                    + "User id/password combinations should be unique!%n",matchingCount,username,password));
        }
        else
        {   System.out.printf("Did not find any user(s) matching the username %s and password %s.%n",username,password);
            //proceed to return false on exit of try-catch block.
        }


    } catch (SQLException e) {
        e.printStackTrace();
    }
    return false;



    }
    /**Checks to see whether the user has permission to access a given page.
     * This is an authorization check, and should be used by the AUTHORIZATION FILTER.
     * For the sake of this demo, I'm keeping per-page permissions, vs. permission classes,
     * and those will be maintained in a table called "pageperms" in database merwebappdb.
     * (yes, I know that this is an asstarded way of doing things, but it makes the coding more interesting.)
     *mysql> CREATE TABLE pageperms(pageurl varchar(255),userid varchar(255), UNIQUE KEY (pageurl, userid));
     * mysql> INSERT INTO pageperms VALUES("/Whatever.jsp","merid");
     * @param url page to which access is sought (url is the relative one as specified in struts.xml.)
     * In this table, there can be multiple entries for each userid and pageurl.  They are not unique.
     * @param username user seeking access
     * @return true if user has access to page; false otherwise
     * @throws DBIntegrityException if there is more than one of the same permission PAIR.
     * though each user can have multiple page permissions, and each page multiple users with permissions
     * to it, record of such permission should only occur once per (userid/pageurl) combo.
     */
    public boolean hasPermissionsToPage(String url, String username) throws DBIntegrityException
    {
    try(Connection conn = DriverManager.getConnection(DBCONSTRING,DBUSER,DBPASSWORD);
        PreparedStatement authznStmt = conn.prepareStatement(GETPERMSSTATEMENT)){
        authznStmt.setString(1, url);
        authznStmt.setString(2, username);
        ResultSet foundauthd = authznStmt.executeQuery();
        if(foundauthd.next())
        {
        int count = foundauthd.getInt(1);
        if(count==1) //exactly 1 match is the only correct match
        {
            System.out.printf("Found exactly one match giving the user %s permission to the page %s.%n",username,url);
            return true;
        }
        else if(count>1)
        {
            throw new DBIntegrityException(String.format("Found more than one (%d) records granting user %s permission to page %s.%n",
                count,username,url));
        }
        }
        else{
          System.out.printf("Did not find any match giving the user %s permission to the page %s.%n",username,url);
        //proceed to return false.
        }

    } catch (SQLException e) {
        e.printStackTrace();
    }
    return false;

    }
    /**Exception indicating some flaw in the data in the database (such as multiple users
     * with the same username.)
     */
    public class DBIntegrityException extends Exception{

    private static final long serialVersionUID = 3669280035176647166L;
    public DBIntegrityException(String message)
    {
        super(message);
    }
    }

    public static void main(String[] args) throws Exception{
    MerUsersDAO mdao = new MerUsersDAO();
    System.out.println(mdao.isUserValid("merid", "merpassword"));
    System.out.println(mdao.isUserValid("impostor", "someotherpassword"));

    System.out.println(mdao.hasPermissionsToPage("/Whatever.jsp","merid"));
    System.out.println(mdao.isUserValid("/Whatever.jsp","impostor"));
    }

}

/*Sample output:
Found 1 user(s) matching the username merid and password merpassword.
true
Found 0 user(s) matching the username impostor and password someotherpassword.
false
Found exactly one match giving the user merid permission to the page /Whatever.jsp.
true
Found 0 user(s) matching the username /Whatever.jsp and password impostor.
false
*/