java - 如何使用带有 CachedRowSet 的 fireTableRowsInserted 在 JTable 中插入新行？

Question

我正在尝试使用按钮从 JTable 中具有 CachedRowSet 数据结构的表单(由文本字段组成)向表中插入新行。创建 GIU 的类(包括按钮，即 CoffeesFrame.java )如下，

public class CoffeesFrame extends JFrame implements RowSetListener {

    private static Connection myConn = null;
    private static String url = null;
    private static String username = null;
    private static String password = null;

   private static JTable table; // The table for displaying data
   private static JFrame frame;

  private static JLabel label_COF_NAME;
  private static JLabel label_SUP_ID;
  private static JLabel label_PRICE;
  private static JLabel label_SALES;
  private static JLabel label_TOTAL;

private static JTextField textField_COF_NAME;
private static JTextField textField_SUP_ID;
private static JTextField textField_PRICE;
private static JTextField textField_SALES;
private static JTextField textField_TOTAL;

private static JButton button_ADD_ROW;
private static JButton button_UPDATE_DATABASE;
private static JButton button_DISCARD_CHANGES;

CoffeesTableModel ctModel;


public CoffeesFrame() {

    url = "jdbc:mysql://localhost:3306/myDemo";
    username = "student";
    password = "student";
}

protected void createAndShowGUI(Connection con) throws SQLException {

    con.setAutoCommit(false);

    System.out.println("The GUI started");
    frame = new JFrame();
    frame.setTitle("My Coffee Frame");

    CachedRowSet crSet = getContentsOfCoffeesTable(con);
    ctModel = new CoffeesTableModel(crSet);
    ctModel.addEventHandelersToRowsSet(this);

    addWindowListener(new WindowAdapter() {

        public void windowClosing(WindowEvent e) {

            try {

                myConn.close();
            }

            catch (SQLException sl) {

                sl.printStackTrace();
            }

            System.exit(0);
        }
    });

    /*
    String[] columnNames = { "First Name", "Last Name", "Sport",
            "# of Years", "Vegetarian" };

    Object[][] data = {
            { "Kathy", "Smith", "Snowboarding", new Integer(5),
                    new Boolean(false) },
            { "John", "Doe", "Rowing", new Integer(3), new Boolean(true) },
            { "Sue", "Black", "Knitting", new Integer(2),
                    new Boolean(false) },
            { "Jane", "White", "Speed reading", new Integer(20),
                    new Boolean(true) },
            { "Joe", "Brown", "Pool", new Integer(10), new Boolean(false) } };

    // table = new JTable(data, columnNames);
    */

    table = new JTable();
    table.setModel(ctModel);

    label_COF_NAME = new JLabel();
    label_SUP_ID = new JLabel();
    label_PRICE = new JLabel();
    label_SALES = new JLabel();
    label_TOTAL = new JLabel();

    textField_COF_NAME = new JTextField(10);
    textField_SUP_ID = new JTextField(10);
    textField_PRICE = new JTextField(10);
    textField_SALES = new JTextField(10);
    textField_TOTAL = new JTextField(10);

    button_ADD_ROW = new JButton();
    button_UPDATE_DATABASE = new JButton();
    button_DISCARD_CHANGES = new JButton();

    label_COF_NAME.setText("Coffee Name:");
    label_SUP_ID.setText("Supplier ID:");
    label_PRICE.setText("Price:");
    label_SALES.setText("Sales:");
    label_TOTAL.setText("Total Sales:");

    textField_COF_NAME.setText("Enter new coffee name");
    textField_SUP_ID.setText("101");
    textField_PRICE.setText("0");
    textField_SALES.setText("0");
    textField_TOTAL.setText("0");

    button_ADD_ROW.setText("Add row to table");
    button_UPDATE_DATABASE.setText("Update database");
    button_DISCARD_CHANGES.setText("Discard changes");

    Container pane = getContentPane();
    pane.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
    pane.setLayout(new GridBagLayout());
    GridBagConstraints cons = new GridBagConstraints();

    cons.fill = GridBagConstraints.BOTH;
    cons.anchor = GridBagConstraints.CENTER;
    cons.weightx = 0.5;
    cons.weighty = 1.0;
    cons.gridx = 0;
    cons.gridy = 0;
    cons.gridwidth = 2;
    pane.add(new JScrollPane(table), cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_START;
    cons.weightx = 0.25;
    cons.weighty = 0;
    cons.gridx = 0;
    cons.gridy = 1;
    cons.gridwidth = 1;
    pane.add(label_COF_NAME, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_END;
    cons.weightx = 0.75;
    cons.weighty = 0;
    cons.gridx = 1;
    cons.gridy = 1;
    cons.gridwidth = 1;
    pane.add(textField_COF_NAME, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.weightx = 0.25;
    cons.weighty = 0;
    cons.anchor = GridBagConstraints.LINE_START;
    cons.gridx = 0;
    cons.gridy = 2;
    cons.gridwidth = 1;
    pane.add(label_SUP_ID, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_END;
    cons.weightx = 0.75;
    cons.weighty = 0;
    cons.gridx = 1;
    cons.gridy = 2;
    cons.gridwidth = 1;
    pane.add(textField_SUP_ID, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_START;
    cons.weightx = 0.25;
    cons.weighty = 0;
    cons.gridx = 0;
    cons.gridy = 3;
    cons.gridwidth = 1;
    pane.add(label_PRICE, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_END;
    cons.weightx = 0.75;
    cons.weighty = 0;
    cons.gridx = 1;
    cons.gridy = 3;
    cons.gridwidth = 1;
    pane.add(textField_PRICE, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_START;
    cons.weightx = 0.25;
    cons.weighty = 0;
    cons.gridx = 0;
    cons.gridy = 4;
    cons.gridwidth = 1;
    pane.add(label_SALES, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_END;
    cons.weightx = 0.75;
    cons.weighty = 0;
    cons.gridx = 1;
    cons.gridy = 4;
    cons.gridwidth = 1;
    pane.add(textField_SALES, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_START;
    cons.weightx = 0.25;
    cons.weighty = 0;
    cons.gridx = 0;
    cons.gridy = 5;
    cons.gridwidth = 1;
    pane.add(label_TOTAL, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_END;
    cons.weightx = 0.75;
    cons.weighty = 0;
    cons.gridx = 1;
    cons.gridy = 5;
    cons.gridwidth = 1;
    pane.add(textField_TOTAL, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_START;
    cons.weightx = 0.5;
    cons.weighty = 0;
    cons.gridx = 0;
    cons.gridy = 6;
    cons.gridwidth = 1;
    pane.add(button_ADD_ROW, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_END;
    cons.weightx = 0.5;
    cons.weighty = 0;
    cons.gridx = 1;
    cons.gridy = 6;
    cons.gridwidth = 1;
    pane.add(button_UPDATE_DATABASE, cons);

    cons.fill = GridBagConstraints.HORIZONTAL;
    cons.anchor = GridBagConstraints.LINE_START;
    cons.weightx = 0.5;
    cons.weighty = 0;
    cons.gridx = 0;
    cons.gridy = 7;
    cons.gridwidth = 1;
    pane.add(button_DISCARD_CHANGES, cons);

    button_ADD_ROW.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {

            // System.out.println("The add row");

            JOptionPane.showMessageDialog(frame, textField_COF_NAME.getText()+" "+
                    Integer.parseInt(textField_SUP_ID.getText().trim())+" "+
                    Float.parseFloat(textField_PRICE.getText().trim())+" "+
                    Integer.parseInt(textField_SALES.getText().trim())+" "+
                    Integer.parseInt(textField_TOTAL.getText().trim()));

            try {

                ctModel.insertRow(textField_COF_NAME.getText(),
                                              Integer.parseInt(textField_SUP_ID.getText().trim()),
                                              Float.parseFloat(textField_PRICE.getText().trim()),
                                              Integer.parseInt(textField_SALES.getText().trim()),
                                              Integer.parseInt(textField_TOTAL.getText().trim()));
              } catch (SQLException sqle) {

                  sqle.printStackTrace();
              }
        }
    });

    frame.add(pane);
    frame.pack();
    frame.setVisible(true);
}

private CachedRowSet getContentsOfCoffeesTable(Connection con)
        throws SQLException {

    CachedRowSet cr = null;

    try {

        cr = new CachedRowSetImpl();
        cr.setType(ResultSet.TYPE_SCROLL_INSENSITIVE);
        cr.setConcurrency(ResultSet.CONCUR_UPDATABLE);
        cr.setUsername(username);
        cr.setPassword(password);
        cr.setUrl(url);

        cr.setCommand("select COF_NAME, SUP_ID, PRICE, SALES, TOTAL from COFFEES");
        cr.execute();

    }

    catch (Exception ex) {

        ex.printStackTrace();
    }

    return cr;
}

@Override
public void rowSetChanged(RowSetEvent event) {

}

@Override
public void rowChanged(RowSetEvent event) {

}

@Override
public void cursorMoved(RowSetEvent event) {

}

public static void main(String[] args) throws SQLException {

    CoffeesFrame cf = new CoffeesFrame();

    try {

        myConn = DriverManager.getConnection(url, username, password);

        if (myConn != null) {

            System.out.println("The app is connected with the database");
        }

        else {

            System.out.println("The connection is not established");
        }
    }

    catch (Exception ex) {

        ex.printStackTrace();
    }

    // launch the swing app
    javax.swing.SwingUtilities.invokeLater(new Runnable() {

        @Override
        public void run() {

            try {
                cf.createAndShowGUI(myConn);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    });
}
}

它使用 CoffeesTableModel.java 进行数据建模，如下所示，

public class CoffeesTableModel extends AbstractTableModel {

    public static CachedRowSet coffeeRowSet;
    public static java.sql.ResultSetMetaData rsMetaData;
    public static int ncolms, nrows;

public CoffeesTableModel(CachedRowSet crSet) throws SQLException {

    this.coffeeRowSet = crSet;
    this.rsMetaData = this.coffeeRowSet.getMetaData();
    ncolms = rsMetaData.getColumnCount();

    this.coffeeRowSet.beforeFirst();
    this.nrows = 0;

    while (this.coffeeRowSet != null & this.coffeeRowSet.next()) {

        nrows++;
    }
    this.coffeeRowSet.beforeFirst();
}

public void addEventHandelersToRowsSet(RowSetListener rsListener) {

    this.coffeeRowSet.addRowSetListener(rsListener);
}

public void insertRow(String coffeeName, int supplierID, float price,
        int sales, int total) throws SQLException {

    try {

        this.coffeeRowSet.moveToInsertRow();
        this.coffeeRowSet.updateString("COF_NAME", coffeeName);
        this.coffeeRowSet.updateInt("SUP_ID", supplierID);
        this.coffeeRowSet.updateFloat("PRICE", price);
        this.coffeeRowSet.updateInt("SALES", sales);
        this.coffeeRowSet.updateInt("TOTAL", total);

        this.coffeeRowSet.insertRow();
        this.coffeeRowSet.moveToCurrentRow();
        fireTableRowsInserted(coffeeRowSet.getRow()-1, coffeeRowSet.getRow()-1);

        // I get SQL error after un-commenting this line 
        // this.coffeeRowSet.acceptChanges();
    }

    catch (Exception ex) {

        ex.printStackTrace();
    }
}

public void close() {

    try {

        coffeeRowSet.getStatement().close();
    }

    catch (Exception ex) {

        ex.printStackTrace();
    }
}

public String getColumnName(int columnIndex) {

    String colName = null;

    try {

        colName = this.rsMetaData.getColumnLabel(columnIndex + 1);
    } catch (Exception ex) {

        ex.toString();
    }

    return colName;
}

@Override
public int getRowCount() {

    return nrows;
}

@Override
public int getColumnCount() {

    return ncolms;
}

public Class getColumnClass(int column) {

    return String.class;
  }

@Override
public Object getValueAt(int rowIndex, int columnIndex) {

    Object o = new Object();
    try {

        this.coffeeRowSet.absolute(rowIndex + 1);
        o = this.coffeeRowSet.getObject(columnIndex + 1);
    }

    catch (SQLException ex) {
        ex.printStackTrace();
    }

    if (o == null){

        return null;
    }

    else{

        return o.toString();
    }   
}

public boolean isEdible(int rowIndex , int colIndex ){

    return false; 
}

public void setValueAt(Object o, int col, int row ){

    System.out.println();
}}

JOptionPane 在按下“将行添加到表格”按钮后显示数据，但是表格中没有插入任何数据。我怎样才能改进代码？

Answer 1

既然您已经为您的问题添加了更多代码，我想知道您为什么要使用 CachedRowSet接口(interface)(参见例如 CachedRowSet: can it still be used to hold ResultSet data? 和 CachedRowSet slower than ResultSet? )。我会考虑从数据库中检索数据并将其存储在常规对象或表模型中。

对于表模型，你也可以使用DefaultTableModel类(class)。这样做的好处是为所有方法创建了一个默认实现，这使您的工作更加轻松。尽可能将表模型与数据库访问分开可能是个好主意。

您可以将所有咖啡数据从数据库复制到 DefaultTableModel实例并关闭数据库连接(您甚至可以在表模型类之外执行此操作)。稍后，当您想要更新数据库时，您可以启动一个新的数据库连接(例如删除所有旧记录并插入所有当前记录；您可以使用 getDataVector 方法检索表模型中的当前记录)。

表格模型类可能如下所示:

import java.sql.*;
import java.util.Vector;
import javax.swing.table.DefaultTableModel;

public class CoffeesTableModelV2 extends DefaultTableModel {
    public CoffeesTableModelV2(Vector data, Vector columnNames) {
        super(data, columnNames);
    }

    public void insertRow(String coffeeName, int supplierID, float price,
                          int sales, int total) {
        final Vector<Object> rowVector = new Vector<>();
        rowVector.add(coffeeName);
        rowVector.add(supplierID);
        rowVector.add(price);
        rowVector.add(sales);
        rowVector.add(total);

        addRow(rowVector);
    }

    @Override
    //public boolean isEdible(int rowIndex, int colIndex) {
    public boolean isCellEditable(int rowIndex, int columnIndex) {
        return false;
    }

    @Override
    public void setValueAt(Object o, int col, int row) {
        final String message = "should not be called for a read-only table model";
        throw new RuntimeException("CoffeesTableModelV2.setValueAt " + message);
    }

    public static CoffeesTableModelV2 createTableModel(ResultSet resultSet)
            throws SQLException {
        return new CoffeesTableModelV2(getData(resultSet), getColumnNames(resultSet));
    }

    private static Vector<Vector<Object>> getData(ResultSet resultSet)
            throws SQLException {
        Vector<Vector<Object>> data = new Vector<>();

        int columnCount = resultSet.getMetaData().getColumnCount();
        while (resultSet.next()) {
            Vector<Object> rowVector = new Vector<>();

            for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
                rowVector.add(resultSet.getObject(columnIndex));
            }

            data.add(rowVector);
        }

        return data;
    }

    private static Vector<String> getColumnNames(ResultSet resultSet) 
            throws SQLException {
        Vector<String> columnNames = new Vector<>();

        ResultSetMetaData metaData = resultSet.getMetaData();
        int columnCount = metaData.getColumnCount();
        for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
            columnNames.add(metaData.getColumnName(columnIndex));
        }

        return columnNames;
    }
}