基于Swing实现Access风格二级可折叠JTable的技术求助

Hey there! I totally get why the JTree + JTable approach wasn't working for you—it's clunky, breaks editing, and never quite matches the clean Access-style behavior you're after. Let's build this directly on top of JTable with custom logic that gives you the collapsible rows, proper editing, and the look you want.

Core Approach #

We'll create a custom data model to track parent/child rows, a custom renderer for the collapse icons, and handle click events to toggle expansion. The key is to keep a flat "display list" for JTable (since JTable expects linear data) that updates when rows are expanded/collapsed.

Step 1: Define a Collapsible Row Data Structure #

First, create a class to hold each row's state and data:

public class CollapsibleRow {
    private boolean isParent;
    private boolean isExpanded;
    private List<Object> rowData;
    private List<CollapsibleRow> children;

    // Constructor for parent rows
    public CollapsibleRow(List<Object> rowData, List<CollapsibleRow> children) {
        this.isParent = true;
        this.isExpanded = false; // Start collapsed by default
        this.rowData = rowData;
        this.children = children;
    }

    // Constructor for child rows
    public CollapsibleRow(List<Object> rowData) {
        this.isParent = false;
        this.isExpanded = false;
        this.rowData = rowData;
        this.children = null;
    }

    // Getters and setters for all fields
    public boolean isParent() { return isParent; }
    public boolean isExpanded() { return isExpanded; }
    public void setExpanded(boolean expanded) { this.isExpanded = expanded; }
    public List<Object> getRowData() { return rowData; }
    public List<CollapsibleRow> getChildren() { return children; }
}

Step 2: Build a Custom Table Model #

This model will manage both the hierarchical data and the flat display list that JTable uses:

public class CollapsibleTableModel extends AbstractTableModel {
    private List<String> columnNames;
    private List<CollapsibleRow> hierarchicalData;
    private List<CollapsibleRow> displayData; // Flat list for JTable

    public CollapsibleTableModel(List<String> columnNames, List<CollapsibleRow> hierarchicalData) {
        this.columnNames = columnNames;
        this.hierarchicalData = hierarchicalData;
        this.displayData = new ArrayList<>();
        updateDisplayList(); // Initialize with collapsed rows
    }

    // Refresh the flat display list based on expanded state
    public void updateDisplayList() {
        displayData.clear();
        for (CollapsibleRow row : hierarchicalData) {
            displayData.add(row);
            if (row.isParent() && row.isExpanded()) {
                displayData.addAll(row.getChildren());
            }
        }
    }

    @Override
    public int getRowCount() {
        return displayData.size();
    }

    @Override
    public int getColumnCount() {
        return columnNames.size();
    }

    @Override
    public String getColumnName(int column) {
        return columnNames.get(column);
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        return displayData.get(rowIndex).getRowData().get(columnIndex);
    }

    @Override
    public boolean isCellEditable(int rowIndex, int columnIndex) {
        // Prevent editing the collapse icon column (first column) for parent rows
        CollapsibleRow row = displayData.get(rowIndex);
        return !(row.isParent() && columnIndex == 0);
    }

    @Override
    public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
        CollapsibleRow row = displayData.get(rowIndex);
        row.getRowData().set(columnIndex, aValue);
        fireTableCellUpdated(rowIndex, columnIndex);
    }

    // Helper to get the display row for renderer/click handling
    public CollapsibleRow getDisplayRow(int rowIndex) {
        return displayData.get(rowIndex);
    }
}

Step 3: Custom Renderer for Collapse Icons & Indentation #

This renderer will draw the +/- icons for parent rows and indent child rows:

public class CollapseCellRenderer extends DefaultTableCellRenderer {
    private final Icon expandIcon = UIManager.getIcon("Tree.expandedIcon");
    private final Icon collapseIcon = UIManager.getIcon("Tree.collapsedIcon");
    private final Border childIndentBorder = BorderFactory.createEmptyBorder(0, 20, 0, 0);

    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
        super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
        
        CollapsibleTableModel model = (CollapsibleTableModel) table.getModel();
        CollapsibleRow rowData = model.getDisplayRow(row);

        if (column == 0) {
            if (rowData.isParent()) {
                setIcon(rowData.isExpanded() ? expandIcon : collapseIcon);
                setBorder(null); // No indent for parents
            } else {
                setIcon(null);
                setBorder(childIndentBorder); // Indent child rows
            }
        } else {
            setIcon(null);
            setBorder(null);
        }
        return this;
    }
}

Step 4: Add Click Handling for Collapse/Expand #

Add a mouse listener to the table to toggle expansion when the collapse icon is clicked:

JTable table = new JTable(model);
table.addMouseListener(new MouseAdapter() {
    @Override
    public void mouseClicked(MouseEvent e) {
        Point clickPoint = e.getPoint();
        int column = table.columnAtPoint(clickPoint);
        int row = table.rowAtPoint(clickPoint);

        if (column == 0 && row != -1) {
            CollapsibleTableModel model = (CollapsibleTableModel) table.getModel();
            CollapsibleRow rowData = model.getDisplayRow(row);
            if (rowData.isParent()) {
                rowData.setExpanded(!rowData.isExpanded());
                model.updateDisplayList();
                model.fireTableDataChanged();
            }
        }
    }
});

Step 5: Match Access-Style Header #

Tweak the table header to match Access's bold, shaded style:

JTableHeader header = table.getTableHeader();
header.setBackground(new Color(215, 225, 235));
header.setFont(header.getFont().deriveFont(Font.BOLD));
header.setBorder(BorderFactory.createEtchedBorder(EtchedBorder.LOWERED));
table.setRowHeight(25); // Adjust row height to fit icons

Step 6: Wire It All Together #

Here's how to initialize the table with sample data:

// Sample column names
List<String> columns = Arrays.asList("Item", "Value", "Notes");

// Sample child rows
CollapsibleRow child1 = new CollapsibleRow(Arrays.asList("Subitem 1", "100", "First child"));
CollapsibleRow child2 = new CollapsibleRow(Arrays.asList("Subitem 2", "200", "Second child"));

// Sample parent row
CollapsibleRow parent = new CollapsibleRow(Arrays.asList("Parent Item", "300", "Parent notes"), Arrays.asList(child1, child2));

// Build model and table
CollapsibleTableModel model = new CollapsibleTableModel(columns, Arrays.asList(parent));
JTable table = new JTable(model);

// Apply renderer to first column
table.getColumnModel().getColumn(0).setCellRenderer(new CollapseCellRenderer());

// Add to scroll pane
JScrollPane scrollPane = new JScrollPane(table);
// Add scrollPane to your frame/panel

Key Notes #

• Editing Support: The isCellEditable method ensures parent rows' first column (icon) isn't editable, but all other cells (parent and child) are.
• Performance: For large datasets, consider optimizing updateDisplayList to avoid full rebuilds, but for most use cases, this approach is fast enough.
• Customization: Swap out the Tree.expandedIcon/Tree.collapsedIcon with custom icons if you want to match Access's exact look.

内容的提问来源于stack exchange，提问作者Learning from masters