java - 使用 Jframe 创建数据库，出现异常未知数据库选择

Question

import java.awt.*;
public class MainWindow {
private JFrame frmMainwindow;
private JTextField textField;
private JTextField textField_1;
private JTextField textField_2;
private JTextField textField_3;
private JTextField textField_4;
private JTextField textField_5;
private JTextField textField_6;
private JTextField textField_7;
private JTextField textField_8;

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

/**
 * Create the application.
 * 
 */

Connection conn = null;
Connection conn1 = null;

public MainWindow() {
    initialize();
    MainPage mp = new MainPage();
    mp.setVisible(true);

}

/**
 * Initialize the contents of the frame.
 */
public void Reset(){
    textField.setText(null);
    textField_1.setText(null);
    textField_2.setText(null);
    textField_3.setText(null);
    textField_4.setText(null);
    textField_5.setText(null);
    textField_6.setText(null);
    textField_7.setText(null);
    textField_8.setText(null);
}

public void DBCreation(){
    conn = CreatingDb.CreateDb();
    String DBName = textField.getText();

    try{
        String query = "CREATE DATABASE " + DBName ;
        PreparedStatement pst = conn.prepareStatement(query);
        pst.executeUpdate();
        JOptionPane.showMessageDialog(null, "DB Created Successful.....");
        pst.close();

    }catch(Exception R){
        JOptionPane.showMessageDialog(null, R);
    }
}

public void Insert(){

     String DBName = textField.getText();
    conn1 = SqlConnection.InsertDB(DBName);


    try{
        String Table1 = "CREATE TABLE PERSONALINFO (PersonName VARCHAR(25),DoorNO VARCHAR(10),Street VARCHAR(25),Village VARCHAR(25),PhoneNo LONGINT(10),UserName VARCHAR(15),Password VARCHAR(10),Hint VARCHAR(50))";
         String Insert1 = "INSERT INTO PERSONALINFO (PersonName,DoorNO,Street,Village,PhoneNo,UserName,Password,Hint) VALUES (?,?,?,?,?,?,?,?)";

        PreparedStatement pstt = conn.prepareStatement(Table1);
        PreparedStatement psti = conn.prepareStatement(Insert1);

        psti.setString(1, textField_1.getText());
        psti.setString(2, textField_2.getText());
        psti.setString(3, textField_3.getText());
        psti.setString(4, textField_4.getText());
        psti.setString(5, textField_5.getText());
        psti.setString(6, textField_6.getText());
        psti.setString(7, textField_7.getText());
        psti.setString(8, textField_8.getText());

        pstt.execute();
        psti.execute();

        JOptionPane.showMessageDialog(null, "Table Created and Data Inserted Successfully....");
        psti.close();
        pstt.close();

    }catch(Exception R){
        JOptionPane.showMessageDialog(null, R);
    }
}

private void initialize() {
    frmMainwindow = new JFrame();
    frmMainwindow.getContentPane().setBackground(Color.WHITE);
    frmMainwindow.getContentPane().setFont(new Font("Times New Roman", Font.BOLD, 14));
    frmMainwindow.setTitle("Create DataBase");
    frmMainwindow.setBounds(100, 100, 668, 416);
    frmMainwindow.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    int height = screenSize.height;
    int width = screenSize.width;
    frmMainwindow.setSize(width/2, height/2);

    // center the jframe on screen
    frmMainwindow.setLocationRelativeTo(null);
    frmMainwindow.getContentPane().setLayout(null);

    JPanel panel_1 = new JPanel();
    panel_1.setBackground(Color.WHITE);
    panel_1.setBounds(120, 70, 426, 205);
    frmMainwindow.getContentPane().add(panel_1);
    panel_1.setLayout(null);
    panel_1.setVisible(false);

    JLabel lblDatabaseName = new JLabel("DataBase Name");
    lblDatabaseName.setBounds(0, 3, 107, 14);
    panel_1.add(lblDatabaseName);
    lblDatabaseName.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblPersonName = new JLabel("Person Name");
    lblPersonName.setBounds(0, 32, 89, 14);
    panel_1.add(lblPersonName);
    lblPersonName.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblDoorNo = new JLabel("Door No");
    lblDoorNo.setBounds(0, 57, 79, 14);
    panel_1.add(lblDoorNo);
    lblDoorNo.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblStreet = new JLabel("Street");
    lblStreet.setBounds(0, 85, 46, 14);
    panel_1.add(lblStreet);
    lblStreet.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblVillage = new JLabel("Village");
    lblVillage.setBounds(0, 110, 46, 14);
    panel_1.add(lblVillage);
    lblVillage.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblPhoneNo = new JLabel("Phone No");
    lblPhoneNo.setBounds(0, 135, 58, 14);
    panel_1.add(lblPhoneNo);
    lblPhoneNo.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblUserbame = new JLabel("UserName");
    lblUserbame.setBounds(232, 3, 79, 14);
    panel_1.add(lblUserbame);
    lblUserbame.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblPassword = new JLabel("Password");
    lblPassword.setBounds(232, 32, 68, 14);
    panel_1.add(lblPassword);
    lblPassword.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblHint = new JLabel("Hint");
    lblHint.setBounds(232, 57, 46, 14);
    panel_1.add(lblHint);
    lblHint.setFont(new Font("Times New Roman", Font.BOLD, 14));

    textField = new JTextField();
    textField.setBounds(117, 0, 105, 20);
    panel_1.add(textField);
    textField.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField.setColumns(10);

    textField_1 = new JTextField();
    textField_1.setBounds(117, 29, 105, 20);
    panel_1.add(textField_1);
    textField_1.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_1.setColumns(10);

    textField_2 = new JTextField();
    textField_2.setBounds(117, 54, 105, 20);
    panel_1.add(textField_2);
    textField_2.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_2.setColumns(10);

    textField_3 = new JTextField();
    textField_3.setBounds(117, 82, 105, 20);
    panel_1.add(textField_3);
    textField_3.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_3.setColumns(10);

    textField_4 = new JTextField();
    textField_4.setBounds(117, 107, 105, 20);
    panel_1.add(textField_4);
    textField_4.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_4.setColumns(10);

    textField_5 = new JTextField();
    textField_5.setBounds(117, 132, 105, 20);
    panel_1.add(textField_5);
    textField_5.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_5.setColumns(10);

    textField_6 = new JTextField();
    textField_6.setBounds(321, 0, 105, 20);
    panel_1.add(textField_6);
    textField_6.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_6.setColumns(10);

    textField_7 = new JTextField();
    textField_7.setBounds(321, 29, 105, 20);
    panel_1.add(textField_7);
    textField_7.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_7.setColumns(10);

    textField_8 = new JTextField();
    textField_8.setBounds(321, 54, 105, 20);
    panel_1.add(textField_8);
    textField_8.setFont(new Font("Times New Roman", Font.BOLD, 14));
    textField_8.setColumns(10);

    JButton btnReset = new JButton("Reset");
    btnReset.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            Reset();
        }
    });
    btnReset.setBounds(232, 171, 89, 23);
    panel_1.add(btnReset);

    JButton btnSave = new JButton("Save");
    btnSave.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            DBCreation();
            Insert();
             Reset();
        }
    });

    btnSave.setBounds(327, 171, 89, 23);
    panel_1.add(btnSave);
    panel_1.setFocusTraversalPolicy(new FocusTraversalOnArray(new Component[]{lblDatabaseName, textField_1, lblPersonName, lblDoorNo, lblStreet, lblVillage, lblPhoneNo, lblUserbame, lblPassword, lblHint, textField_2, textField_3, textField_4, textField_5, textField_6, textField_7, textField_8, btnSave, btnReset, textField}));

    JPanel panel = new JPanel();
    panel.setBackground(Color.WHITE);
    panel.setBounds(217, 122, 233, 101);
    frmMainwindow.getContentPane().add(panel);
    panel.setLayout(null);

    JLabel lblCreateDatabase = new JLabel("Create DataBase");
    lblCreateDatabase.setBounds(0, 4, 120, 14);
    panel.add(lblCreateDatabase);
    lblCreateDatabase.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblOpenDatabase = new JLabel("Open DataBase");
    lblOpenDatabase.setBounds(0, 42, 120, 14);
    panel.add(lblOpenDatabase);
    lblOpenDatabase.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JLabel lblNewLabel = new JLabel("Delete DataBase");
    lblNewLabel.setBounds(0, 82, 120, 14);
    panel.add(lblNewLabel);
    lblNewLabel.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JButton btnNew = new JButton("New");
    btnNew.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            panel.setVisible(false);
            panel_1.setVisible(true);
        }
    });
    btnNew.setBounds(144, 0, 89, 23);
    panel.add(btnNew);
    btnNew.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JButton btnSelect = new JButton("Select");
    btnSelect.setBounds(144, 38, 89, 23);
    panel.add(btnSelect);
    btnSelect.setFont(new Font("Times New Roman", Font.BOLD, 14));

    JButton btnRemove = new JButton("Remove");
    btnRemove.setBounds(144, 78, 89, 23);
    panel.add(btnRemove);
    btnRemove.setFont(new Font("Times New Roman", Font.BOLD, 14));
}
}

我的第二个java文件

public class SqlConnection {

Connection conn1 = null;

public static Connection InsertDB(String DBName){
    String value = DBName;
    try{
        Class.forName("com.mysql.jdbc.Driver");
        String DB = "jdbc:mysql://localhost:3306/";
        Connection conn = DriverManager.getConnection(DB+value,"root","");
        JOptionPane.showMessageDialog(null,value);
        return conn;
    }catch(Exception e){
        JOptionPane.showMessageDialog(null,e);
        return null;
    }
}


}

我的第三个java文件

public class CreatingDb {

Connection conn = null;

public static Connection CreateDb(){
    try{
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/","root","");
        return conn;
    }catch(Exception e){
        JOptionPane.showMessageDialog(null,e);
        return null;
    }
}
}

我的第四个java文件..

public class MainPage extends JFrame {

private JPanel contentPane;

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

/**
 * Create the frame.
 */
public MainPage() {
    setExtendedState(Frame.MAXIMIZED_BOTH);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);

    JMenuBar menuBar = new JMenuBar();
    setJMenuBar(menuBar);

    JMenu mnFile = new JMenu("File");
    menuBar.add(mnFile);

    JMenuItem mntmNew = new JMenuItem("New");
    mnFile.add(mntmNew);

    JMenuItem mntmOpen = new JMenuItem("Open");
    mnFile.add(mntmOpen);

    JMenuItem mntmSave = new JMenuItem("Save");
    mnFile.add(mntmSave);

    JMenuItem mntmSaveAs = new JMenuItem("Save As...");
    mnFile.add(mntmSaveAs);

    JMenuItem mntmExit = new JMenuItem("Exit");
    mnFile.add(mntmExit);

    JMenu mnEdit = new JMenu("Edit");
    menuBar.add(mnEdit);

    JMenu mnHelp = new JMenu("Help");
    menuBar.add(mnHelp);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setLayout(new BorderLayout(0, 0));
    setContentPane(contentPane);
}
}

我已经导入了所需的包...在上面的代码中，我在应用程序开始时使用文本字段创建数据库。数据库已成功创建，但我无法访问创建的数据库。它显示 java.sql.Exception:未知的数据库选择。请任何人帮助我......

Answer 1

 String DB = "jdbc:mysql://localhost:3306/";
 Connection conn = DriverManager.getConnection(DB+value,"root","");

我认为你的问题正在追加。您不附加 DB + 值。给出密码。