jtable 合并单元格

在 JTable 中合并单元格需要重写 TableCellRenderer 和 TableCellEditor 接口，以自定义单元格绘制和编辑。以下是一个简单的例子，可以将第一行和第二行第一列的单元格合并：

import java.awt.Component;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellEditor;
import javax.swing.table.TableCellRenderer;

public class MergeCellTable extends JFrame {
    private static final long serialVersionUID = 1L;
    private JTable table;

    public MergeCellTable() {
        setTitle("Merge Cell Table");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(300, 200);

        DefaultTableModel model = new DefaultTableModel() {
            private static final long serialVersionUID = 1L;

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

        model.addColumn("Column 1");
        model.addColumn("Column 2");
        model.addColumn("Column 3");
        model.addColumn("Column 4");

        model.addRow(new Object[] { "Row 1, Column 1", "Row 1, Column 2", "Row 1, Column 3", "Row 1, Column 4" });
        model.addRow(new Object[] { "Row 2, Column 1", "Row 2, Column 2", "Row 2, Column 3", "Row 2, Column 4" });
        model.addRow(new Object[] { "Row 3, Column 1", "Row 3, Column 2", "Row 3, Column 3", "Row 3, Column 4" });

        table = new JTable(model);
        table.setRowHeight(20);
        table.getColumnModel().getColumn(0).setCellRenderer(new MergeCellRenderer());
        table.getColumnModel().getColumn(0).setCellEditor(new MergeCellEditor());
        JScrollPane scroll = new JScrollPane(table);

        getContentPane().add(scroll);
        setVisible(true);
    }

    public static void main(String[] args) {
        new MergeCellTable();
    }

    private class MergeCellRenderer extends DefaultTableCellRenderer implements TableCellRenderer {
        private static final long serialVersionUID = 1L;

        public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
                int row, int column) {
            if (row == 0 || row == 1 && column == 0) {
                setText((String) value);
                setHorizontalAlignment(CENTER);
                setVerticalAlignment(CENTER);
                setOpaque(true);
                setBackground(table.getBackground());
            } else {
                setText((String) value);
                setHorizontalAlignment(LEFT);
                setVerticalAlignment(CENTER);
                setOpaque(true);
                setBackground(table.getBackground());
            }

            return this;
        }
    }

    private class MergeCellEditor extends DefaultTableCellRenderer implements TableCellEditor {
        private static final long serialVersionUID = 1L;

        public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
            return getTableCellRendererComponent(table, value, isSelected, false, row, column);
        }

        public Object getCellEditorValue() {
            return getText();
        }

        public boolean isCellEditable(java.util.EventObject e) {
            return true;
        }

        public boolean shouldSelectCell(java.util.EventObject anEvent) {
            return true;
        }

        public boolean stopCellEditing() {
            return true;
        }

        public void cancelCellEditing() {
        }

        public void addCellEditorListener(javax.swing.event.CellEditorListener l) {
        }

        public void removeCellEditorListener(javax.swing.event.CellEditorListener l) {
        }
    }
}

这个例子只是演示了一种简单的合并单元格的方法，更复杂的需求需要更复杂的实现方式。