我正在使用 JDBC 检查数据库中的用户名和密码以授予对我的 gui 的登录访问权限，但是当我尝试测试 JDBC 是否正常工作时，当输入错误的用户名和密码时，它不会阻止访问..
下面是我的代码，我相信它正确连接了数据库，因为当我按下登录按钮时，它会输出运行检查登录和用户已验证。
class usernamecheck {
static final String DATABASE_URL = "jdbc:mysql://localhost:3306/mysql";
static final String USERNAME = "root";
static final String PASSWORD = "root";
// launch the application
public static boolean checkLogin(String username, String password)
throws SQLException {
System.out.print("Running Check Login \n");
Connection connection = null; // manages connection
PreparedStatement pt = null; // manages prepared statement
// connect to database usernames and query database
try {
// establish connection to database
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection(DATABASE_URL, "root", "root");
// query database
pt = con.prepareStatement("select userName,password from mysql.person where userName=?");
// process query results
pt.setString(1, username);
ResultSet rs = pt.executeQuery();
String orgUname = "", orPass = "";
while (rs.next()) {
orgUname = rs.getString("userName");
orPass = rs.getString("password");
} //end while
if (orPass.equals(password)) {
//do something
return true;
} else {
//do something
}
}//end try
catch (Exception e) {
} //end catch
return false;
} //end main
}
带有 GUI 的代码
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.sql.*;
public class Login extends JFrame {
private JTextField jtfUsername, jtfPassword;
private JButton backButton, loginButton;
private JMenuItem jmiLogin, jmiBack, jmiHelp, jmiAbout;
Login() {
//create menu bar
JMenuBar jmb = new JMenuBar();
//set menu bar to the applet
setJMenuBar(jmb);
//add menu "operation" to menu bar
JMenu optionsMenu = new JMenu("Options");
optionsMenu.setMnemonic('O');
jmb.add(optionsMenu);
//add menu "help"
JMenu helpMenu = new JMenu("Help");
helpMenu.setMnemonic('H');
helpMenu.add(jmiAbout = new JMenuItem("About", 'A'));
jmb.add(helpMenu);
//add menu items with mnemonics to menu "options"
optionsMenu.add(jmiLogin = new JMenuItem("Login", 'L'));
optionsMenu.addSeparator();
optionsMenu.add(jmiBack = new JMenuItem("Back", 'B'));
//panel p1 to holds text fields
JPanel p1 = new JPanel(new GridLayout(2, 2));
p1.add(new JLabel("Username"));
p1.add(jtfUsername = new JTextField(15));
p1.add(new JLabel("Password"));
p1.add(jtfPassword = new JPasswordField(15));
//panel p2 to holds buttons
JPanel p2 = new JPanel(new FlowLayout());
p2.add(backButton = new JButton("Back"));
p2.add(loginButton = new JButton("Login"));
//Panel with image??????
//add panels to frame
JPanel panel = new JPanel(new GridLayout(2, 1));
panel.add(p1, BorderLayout.CENTER);
panel.add(p2, BorderLayout.SOUTH);
add(panel, BorderLayout.CENTER);
setTitle("Main Page");
//listners for exit menuitem and button
jmiBack.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Welcome welcome = new Welcome();
welcome.setVisible(true);
welcome.setSize(500, 500);
welcome.setLocationRelativeTo(null);
registerInterface regFace = new registerInterface();
regFace.setVisible(false);
Login.this.dispose();
Login.this.setVisible(false);
}
});
backButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Welcome welcome = new Welcome();
welcome.setVisible(true);
welcome.setSize(500, 500);
welcome.setLocationRelativeTo(null);
registerInterface regFace = new registerInterface();
regFace.setVisible(false);
Login.this.dispose();
Login.this.setVisible(false);
}
});
//listner for about menuitem
jmiAbout.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null,
"This is the login panel"
+ "\n Assignment for University",
"About", JOptionPane.INFORMATION_MESSAGE);
}
});
//action listeners for Login in button and menu item
loginButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
usernamecheck.checkLogin(jtfUsername.getText(), jtfPassword.getText()); {
System.out.println("User is validated");
}
} catch (SQLException se) {
}
MainMenu mainmenu = new MainMenu();
mainmenu.setVisible(true);
mainmenu.setSize(500, 500);
mainmenu.setLocationRelativeTo(null);
registerInterface regFace = new registerInterface();
regFace.setVisible(false);
Login.this.dispose();
Login.this.setVisible(false);
}
});
jmiLogin.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
MainMenu mainmenu = new MainMenu();
mainmenu.setVisible(true);
mainmenu.setSize(500, 500);
mainmenu.setLocationRelativeTo(null);
registerInterface regFace = new registerInterface();
regFace.setVisible(false);
Login.this.dispose();
Login.this.setVisible(false);
}
});
}
public static void main(String arg[]) {
Login frame = new Login();
frame.setSize(500, 500);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
class usernamecheck {
static final String DATABASE_URL = "jdbc:mysql://localhost:3306/mysql";
static final String USERNAME = "root";
static final String PASSWORD = "root";
// launch the application
public static boolean checkLogin(String username, String password)
throws SQLException {
System.out.print("Running Check Login \n");
Connection connection = null; // manages connection
PreparedStatement pt = null; // manages prepared statement
Statement stmt = null;
String query="select userName from person where userName = ? and password = ?";
// connect to database usernames and query database
try {
// establish connection to database
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection(DATABASE_URL, "root", "root");
// query database
pt = con.prepareStatement("select userName from person where userName = ? and password = ?");
// process query results
pt.setString(1, username);
ResultSet rs = pt.executeQuery(query);
String orgUname = "", orPass = "";
while (rs.next()) {
orgUname = rs.getString("userName");
orPass = rs.getString("password");
} //end while
if (orPass.equals(password) && orgUname.equals(username)) {
//do something
return false;
} else {
//do something
return true;
}
}//end try
catch (Exception e) {
} //end catch
return true;
} //end main
}