Java 数据库连接。尝试通过sql登录jframe获取逻辑错误

Question

我有一个带有登录屏幕的 swing jframe，我正在尝试执行 phpmyadmin 数据库查询。它连接到数据库，但不允许我登录，只是无限显示“无效的用户名或密码”这是代码。

JPasswordField jpfpass;
JLabel jlabuser, jlabpass;

public RychlikSystemversion0(String name) {
    super(name);
    btnlogin = new JButton("Login");
    btenreset = new JButton("Reset");
    btnexit = new JButton("Exit");

    jtfuser = new JTextField();
    jpfpass = new JPasswordField();

    jlabuser = new JLabel("Ussername");
    jlabpass = new JLabel("Password");

    this.setLayout(null);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    btnlogin.addActionListener(this);
    btenreset.addActionListener(this);
    btnexit.addActionListener(this);

    jlabuser.setBounds(10, 10, 120, 20);
    jlabpass.setBounds(10, 30, 120, 20);
    jtfuser.setBounds(140, 10, 300, 20);
    jpfpass.setBounds(140, 30, 300, 20);

    btnlogin.setBounds(140, 55, 100, 20);
    btenreset.setBounds(240, 55, 100, 20);
    btnexit.setBounds(340, 55, 100, 20);

    this.add(jlabuser);
    this.add(jlabpass);
    this.add(jtfuser);
    this.add(jpfpass);
    this.add(btnlogin);
    this.add(btenreset);
    this.add(btnexit);

    this.setSize(500, 300);
    this.setVisible(true);
}

public void actionPerformed(ActionEvent ae) {
    //String USERNAME = "root";
    //String PASSWORD = "root ";
    //String CONN_STRING = "jdbc:mysql://localhost::3307/osdesign";

    Connection connection;
    PreparedStatement ps;
    try {
        String dbName = "osdesign";
        String dbUserName = "root";
        String dbPassword = "";
        //String u = jtfuser.getText();
        //String p =jpfpass.getName();
        String connectionString = "jdbc:mysql://localhost/" + dbName + "?user="
                + dbUserName + "&password=" + dbPassword
                + "&useUnicode=true&characterEncoding=UTF-8";
        connection = DriverManager.getConnection(connectionString);
        JOptionPane.showMessageDialog(null, "Connected!");
        String sql = "SELECT * FROM `userlist` WHERE `UsrName` = ? AND `UsrPass` = ?";
        ps = connection.prepareStatement(sql);

        jtfuser.setText("Test");
        jpfpass.setText("Test");
        ps.setString(1, jtfuser.getText());
        ps.setString(2, jpfpass.getName());
        //JFrame panel = new JFrame();
        ResultSet result = ps.executeQuery();
        btnlogin.equals(result);
        // panel.add(btnlogin);
        //   panel.add(jpfpass.getName(),btnlogin);
        if (result.next()) {
            JOptionPane.showMessageDialog(null, "Login Sucessful");  //Wont execute statement
        } else {
            JOptionPane.showMessageDialog(null,  "Invalid user name or password");     //Always does this
    }
} catch (SQLException ex) {
        Logger.getLogger(RychlikSystemversion0.class.getName()).log(Level.SEVERE, null, ex);
    }
}

public static void main(String[] args) {
    RychlikSystemversion0 ls = new RychlikSystemversion0("System login");
}

我已经尝试了几种方法，但仍然不允许我登录。有什么帮助吗？

Answer 1

问题在于:

jpfpass = new JPasswordField();
//[..]
ps.setString(2, jpfpass.getName());

方法getName() ，不会在字段中为您提供密码，而是为您提供组件的名称(在您的代码中甚至未设置)。

如果想从JPasswordField获取密码，需要使用getPassword() 。此方法返回一个 char[]，因此您需要更改代码以使用:

ps.setString(2, new String(jpfpass.getPassword()));

如果将来你遇到这样的问题，首先检查你的假设。在调试器中单步执行代码并检查这些值是否符合您的预期，或者只是添加一些相关值的调试 System.out.println(..)。