主题：作业之六：用户登录认证

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

import javax.swing.JOptionPane;

public class Exec {
        public static void main(String[] args) {
                Connection con;
                Statement stm;
                ResultSet res;
                ResultSetMetaData rsmd;
                String username = JOptionPane.showInputDialog("用户名称：");
                String password = JOptionPane.showInputDialog("用户密码：");
                boolean flag = false;

                try {
                        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

                        con = DriverManager.getConnection("jdbc:odbc:StuSQL");

                        stm = con.createStatement();

                        res = stm.executeQuery("select * from stu");

                        rsmd = res.getMetaData();

                        while (res.next()) {
                                if (username.equals(res.getString(1).trim())
                                                && password.equals(res.getString(2).trim())) {
                                        flag = true;
                                        break;
                                }
                        }
                        if (flag) {
                                JOptionPane.showMessageDialog(null, "合法用户！");
                        } else {
                                JOptionPane.showMessageDialog(null, "非法用户！");
                        }

                        con.close();
                } catch (Exception ex) {
                }
        }
}