Question

我创建了一个主窗口，如果用户是系统管理员，员工或财务成员，用户将点击该窗口，我的一个问题是他们不在屏幕中心，我该怎么做？其次，我想要它的工作方式，当我点击财务按钮，主窗口将关闭，它将带我到我的登录屏幕，我该怎么办？这是我的MainWindow代码

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.CardLayout;
import javax.swing.JEditorPane;
import javax.swing.SpringLayout;
import javax.swing.JButton;
import javax.swing.JTextField;
import javax.swing.JLabel;
import javax.swing.JFormattedTextField;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;


    public class MainWindow extends JFrame {

        private JPanel contentPane;

        /**
         * Launch the application.
         */
        public static void main(String[] args) {
            EventQueue.invokeLater(new Runnable() {
                public void run() {
                    try {
                        MainWindow frame = new MainWindow();
                        frame.setVisible(true);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });
        }

        /**
         * Create the frame.
         */
        public MainWindow() {
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            setBounds(100, 100, 333, 191);
            contentPane = new JPanel();
            contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
            setContentPane(contentPane);
            contentPane.setLayout(new BorderLayout(0, 0));

            JButton btnNewButton = new JButton("Employee");
            contentPane.add(btnNewButton, BorderLayout.WEST);

            JButton btnNewButton_1 = new JButton("Finance");
            btnNewButton_1.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent arg0) {
                    Login login = new Login();
                }
            });
            contentPane.add(btnNewButton_1, BorderLayout.CENTER);

            JButton btnNewButton_2 = new JButton("System Admin");
            contentPane.add(btnNewButton_2, BorderLayout.EAST);

            JLabel lblNewLabel = new JLabel("Welcome");
            contentPane.add(lblNewLabel, BorderLayout.NORTH);
        }

    }

这是我的登录表单代码

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JButton;
import javax.swing.JPanel;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class Login extends JFrame {

    private JLabel label1, label2;
    private JButton submit;
    private JTextField textfield1;
    private JPasswordField passfield;
    private JPanel panel;

    public Login() {

        setSize(300, 100);
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        label1 = new JLabel("User ID:");
        textfield1 = new JTextField(15);
        label2 = new JLabel("Password:");
        passfield = new JPasswordField(15);
        submit = new JButton("Submit");
        panel = new JPanel(new GridLayout(3, 1));

        panel.add(label1);
        panel.add(textfield1);
        panel.add(label2);
        panel.add(passfield);
        panel.add(submit);
        add(panel, BorderLayout.CENTER);

        ButtonHandler handler = new ButtonHandler();
        submit.addActionListener(handler);
    }// end login constructor

    private class ButtonHandler implements ActionListener {

        public void actionPerformed(ActionEvent event) {

            String user = textfield1.getText();
            char[] passChars = passfield.getPassword();
            Connection conn = Jdbc.dbConn();
            PreparedStatement ps = null;
            ResultSet rs = null;
            String pass = new String(passChars);

            if (passChars != null) {
                String sql = "SELECT employee_ID, employee_password FROM  user WHERE employee_ID = ? AND employee_password = ?";

                try {
                    ps = conn.prepareStatement(sql);
                    ps.setString(1, user);
                    ps.setString(2, pass);
                    rs = ps.executeQuery();
                    if (rs.next()) {
                        JOptionPane.showMessageDialog(null,"Welcome! "+user);
                    } else {
                        JOptionPane.showMessageDialog(null, "Wrong Input");
                    }
                } catch (Exception e) {
                        e.printStackTrace();
                } finally {
                    try {
                        rs.close();
                        ps.close();
                        conn.close();
                    } catch (Exception ee) {
                            ee.printStackTrace();
                    }
                }
            }// end actionPerformed
        }// End ButtonHandler
    }// End of class
}

Answer 1

您需要carefully choose a layout manager以满足您的需求。您目前正在使用的BorderLayout似乎没有做您想做的事情。

尝试将三个按钮添加到JPanel，然后将该面板设置为框架的内容窗格。 JPanel默认情况下使用FlowLayout，这应该可以解决问题。

Answer 2

一些建议：

不要将setBounds()用于MainWindow（JFrame）。使用一些布局并在最后使用pack()。如果您想手动设置大小，那么您也可以使用setSize()。
要关闭当前窗口并打开登录框，请添加setVisible(false)或dispose()并创建登录对象并使其可见。
要使框架处于中心位置，请尝试setLocationRelativeTo(null);。
请勿使用label1，textFiled2，btnNewButton等变量名称...使用适当的名称来反映其使用情况。

第2点的例子：

    btnNewButton_1.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            setVisible(false);
            Login login = new Login();
        }
    });

新的按钮窗口和UI对齐

2 个答案: