SQLException：找不到適用於jdbc：derby的驅動程序：錯誤

Question

我們的教授為我們提供了一個示例，說明了他使用GUI在表中進行更改時在“嵌入數據庫”中的代碼。

這是我使用的代碼

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
import java.awt.*;
import java.awt.event.*;
import static java.awt.GridBagConstraints.*;
import java.sql.*;
import java.util.*;

public class Gadgets2
{
    private JPanel mainPanel, topPanel, midPanel, bottomPanel;
    private JTextField txtBRAND, txtNAME, txtCOLOR;
    private JButton btnAdd, btnEdit, btnDelete;

    private JTable tblGadgets;
    private DefaultTableModel model;
    private Vector<Object> columnNames = new Vector<Object>();
    private Vector<Object> data = new Vector<Object>();

    private String dbName = "GadgetsDB";
    private String connectionURL = "jdbc:derby://localhost:1527/" + dbName + ";create=true";
    private Connection conn;
    private Statement stmt;
    private ResultSet rs;

public Gadgets2()
{
    connectDB();
    loadGadgets();
    buildGUI();
}

private void addComponent(Container container, Component component,
    int gridX, int gridY, int gridWidth, int gridHeight, int anchor, int fill)
{
    Insets insets = new Insets(2, 2, 2, 2);
    GridBagConstraints gbc = new GridBagConstraints(gridX, gridY, gridWidth,
        gridHeight, 1.0, 1.0, anchor, fill, insets, 0, 0);
    container.add(component, gbc);
}

private void buildGUI()
{
    JFrame frame = new JFrame("Gadgets");
    JLabel lblGadgets = new JLabel("Gadgets");
    mainPanel = new JPanel(new GridBagLayout());
    topPanel = new JPanel(new GridBagLayout());
    midPanel = new JPanel(new GridBagLayout());
    bottomPanel = new JPanel(new GridBagLayout());

    model = new DefaultTableModel(data, columnNames) 
    {
        @Override
        public Class getColumnClass(int column)
        {
            for (int row = 0; row < getRowCount(); row++)
            {
                Object o = getValueAt(row, column);

                if (o != null)
                {
                    return o.getClass();
                }
            }
            return Object.class;
        }

        @Override
        public boolean isCellEditable(int row, int column)
        {
            return false;
        }
    };


    tblGadgets = new JTable( model );

    tblGadgets.getSelectionModel().addListSelectionListener(
      new ListSelectionListener()
      {
        public void valueChanged(ListSelectionEvent event) {

            if (! event.getValueIsAdjusting())
            {
                showGadgetsInfo();
            }
        }
      });
    tblGadgets.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    tblGadgets.setCellSelectionEnabled(false);
    tblGadgets.setColumnSelectionAllowed(false);
    tblGadgets.setRowSelectionAllowed(true);

    JScrollPane scrollPane = new JScrollPane( tblGadgets, 
        JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
        JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);         

    addComponent(topPanel, lblGadgets, 0, 0, 1, 1, BASELINE_LEADING, NONE);
    addComponent(topPanel, scrollPane, 0, 1, 1, 1, BASELINE_LEADING, NONE);

    JLabel lblBRAND = new JLabel("BRAND");
    JLabel lblNAME = new JLabel("NAME");
    JLabel lblCOLOR = new JLabel("COLOR");

    txtBRAND = new JTextField(20);
    txtNAME = new JTextField(20);
    txtCOLOR = new JTextField(10);

    addComponent(midPanel, lblBRAND, 0, 0, 1, 1, BASELINE_LEADING, NONE);
    addComponent(midPanel, txtBRAND, 1, 0, 1, 1, BASELINE_LEADING, NONE);
    addComponent(midPanel, lblNAME, 0, 1, 1, 1, BASELINE_LEADING, NONE);
    addComponent(midPanel, txtNAME, 1, 1, 1, 1, BASELINE_LEADING, NONE);
    addComponent(midPanel, lblCOLOR, 0, 2, 1, 1, BASELINE_LEADING, NONE);
    addComponent(midPanel, txtCOLOR, 1, 2, 1, 1, BASELINE_LEADING, NONE);

    btnAdd = new JButton("Add");
    btnEdit = new JButton("Edit");
    btnDelete = new JButton("Delete");

    addComponent(bottomPanel, btnAdd, 0, 0, 1, 1, BASELINE_LEADING, NONE);
    addComponent(bottomPanel, btnEdit, 1, 0, 1, 1, BASELINE_LEADING, NONE);
    addComponent(bottomPanel, btnDelete, 2, 0, 1, 1, BASELINE_LEADING, NONE);

    addComponent(mainPanel, topPanel, 0, 0, 1, 1, BASELINE_LEADING, NONE);
    addComponent(mainPanel, midPanel, 0, 1, 1, 1, CENTER, BOTH);
    addComponent(mainPanel, bottomPanel, 0, 2, 1, 1, BASELINE_TRAILING, NONE);

    frame.setContentPane(mainPanel);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    scrollPane.setPreferredSize(new Dimension(600,150));

    frame.pack();

    frame.setLocationRelativeTo(null);
    frame.setResizable(false);
    frame.setVisible(true);

    setTextfieldsEditable(false);

    btnAdd.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent event)
            {
                if (btnAdd.getText().equals("Add"))
                {
                    btnAdd.setText("Save");
                    btnEdit.setText("Cancel");
                    btnDelete.setVisible(false);
                    tblGadgets.setEnabled(false);

                    clearTextfields();
                    setTextfieldsEditable(true);

                } else if (btnAdd.getText().equals("Save"))
                {
                    btnAdd.setText("Add");
                    btnEdit.setText("Edit");
                    btnDelete.setVisible(true);
                    tblGadgets.setEnabled(true);
                    setTextfieldsEditable(false);
                    doInsertNewRecord();                       
                    loadGadgets();
                    clearTextfields();

                }
            }
        }
    );

    btnEdit.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent evt)
            {
                if (tblGadgets.getSelectedRow()<0)
                {
                    JOptionPane.showMessageDialog(null, "Please select an item in the table to edit.");
                    return;
                }

                if (btnEdit.getText().equals("Cancel"))
                {
                    btnAdd.setText("Add");
                    btnEdit.setText("Edit");
                    btnDelete.setVisible(true);
                    tblGadgets.setEnabled(true); 
                    setTextfieldsEditable(false);
                } else if (btnEdit.getText().equals("Edit"))
                {
                    btnAdd.setVisible(false);
                    btnEdit.setText("Save");
                    btnDelete.setText("Cancel");
                    tblGadgets.setEnabled(false);
                    setTextfieldsEditable(true);
                } else if(btnEdit.getText().equals("Save")) 
                {
                    btnAdd.setVisible(true);
                    btnEdit.setText("Edit");
                    btnDelete.setText("Delete");
                    tblGadgets.setEnabled(true); 
                    setTextfieldsEditable(false);
                    doSaveEdits();
                    loadGadgets();

                }
            }
        }
    );

    btnDelete.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent evt)
            {
                if (btnDelete.getText().equals("Cancel"))
                {
                    btnAdd.setVisible(true);
                    btnEdit.setText("Edit");
                    btnDelete.setText("Delete");
                    tblGadgets.setEnabled(true);                        
                } else if (btnDelete.getText().equals("Delete")) {

                    if (tblGadgets.getSelectedRow() <0)
                    {
                        JOptionPane.showMessageDialog(null, 
                        "You haven't selected any item. Please select the gadget from \n" +
                        "the list.");
                        return;
                    }

                    String message = "Proceed to delete the selected record?";
                    String title = "Confirm delete";

                    int reply = JOptionPane.showConfirmDialog(
                        null, message, title, JOptionPane.YES_NO_OPTION);
                    if (reply == JOptionPane.YES_OPTION)
                    {
                        doDeleteRecord();
                        loadGadgets(); 
                        tblGadgets.repaint();
                        clearTextfields();
                    }                        
                }
            }
        }

    );
}

private void connectDB()
{

    try
    {
        conn = DriverManager.getConnection(connectionURL);
    } catch (SQLException ex) {
        displaySQLErrors(ex);
    }
}

private void loadGadgets()
{                
    try
    {
        columnNames.clear();
        data.clear();

        stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
            ResultSet.CONCUR_READ_ONLY);
        rs = stmt.executeQuery("SELECT BRAND, NAME, COLOR FROM Gadgets");       

        ResultSetMetaData md = rs.getMetaData();
        int columns = md.getColumnCount();

        for (int i = 1; i <= columns; i++)
        {
            columnNames.addElement( md.getColumnName(i) );
        }

        while (rs.next())
        {
            Vector<Object> row = new Vector<Object>(columns);

            for (int i = 1; i <= columns; i++)
            {
                row.addElement( rs.getObject(i) );
            }

            data.addElement( row );
        }

    } catch (SQLException ex){
        displaySQLErrors(ex);
    } catch (Exception ex){
        JOptionPane.showMessageDialog(null, ex.getMessage());
    }
 }

private void doInsertNewRecord()
{
    try
    {
        Statement stmt = conn.createStatement();
        int i = stmt.executeUpdate("INSERT INTO Gadgets (BRAND, NAME, COLOR) " + 
            "VALUES ('" + txtBRAND.getText() + "', '" + 
            txtNAME.getText() + "', " + 
            txtCOLOR.getText() + ")");
    } catch (SQLException ex){
        displaySQLErrors(ex);
    }
}

private void doSaveEdits()
{
    try {
        Statement stmt = conn.createStatement();
        int i = stmt.executeUpdate("UPDATE Gadgets " +
        "SET BRAND = '" + txtBRAND.getText() + "', " +
        "NAME = '" + txtNAME.getText() + "', " +
        "COLOR = '" + txtCOLOR.getText() + " WHERE BRAND ='" + 
        tblGadgets.getValueAt(tblGadgets.getSelectedRow(), 0).toString() + "'");

    } catch (SQLException ex)
    {
        displaySQLErrors(ex);
    } catch (Exception ex1) {
        ex1.printStackTrace();
    }
}

private void doDeleteRecord()
{
    try {
        Statement stmt = conn.createStatement();
        int i = stmt.executeUpdate(
            "DELETE FROM Gadgets where BRAND = '" + 
            txtBRAND.getText() + "'");                

    } catch (SQLException ex) {
        displaySQLErrors(ex);
    }
}

private void clearTextfields()   
{
    txtBRAND.setText("");
    txtNAME.setText("");
    txtCOLOR.setText("");
}

private void setTextfieldsEditable(boolean editable)
{
    txtBRAND.setEditable(editable);
    txtNAME.setEditable(editable);
    txtCOLOR.setEditable(editable);
}
private void showGadgetsInfo()
{
    try
    {

        rs.beforeFirst();
        while(rs.next())
        {
            if (rs.getString("BRAND").equals(
                tblGadgets.getValueAt(tblGadgets.getSelectedRow(), 0).toString()))
                break;
        }

        if (!rs.isAfterLast())
        {
            txtBRAND.setText(rs.getString("BRAND"));
            txtNAME.setText(rs.getString("NAME"));
            txtCOLOR.setText(rs.getString("COLOR") + "");
        }

    } catch (SQLException ex) {
        displaySQLErrors(ex);
    }        
}


private void displaySQLErrors(SQLException ex)
{
    String errorText = "SQL Exception: " + ex.getMessage() + "\n" +
            "SQL state: " + ex.getSQLState() + "\n" + 
            "Vendor Error: " + ex.getErrorCode();
    JOptionPane.showMessageDialog(null, errorText);
}



public static void main(String[] args)
{
    Gadgets2 app = new Gadgets2();

}

}

編寫此代碼時，我一直遇到一些麻煩...我在其中做錯了嗎？

Answer 1

沒有合適的驅動程序-將其添加到您的類路徑中。 您將需要derbyclient.jar或類似文件。

請在此處查看一些說明： http : //www.codejava.net/java-se/jdbc/connect-to-apache-derby-java-db-via-jdbc