java swing Jtable 合并单元格

在Java Swing中，可以使用JTable实现表格的展示和操作。JTable提供了一些方法可以用来合并单元格。

下面是一个简单的示例代码，演示如何使用JTable合并单元格：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import javax.swing.UIManager;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.JTableHeader;

public class JTableMergeCellDemo extends JFrame {

    private static final long serialVersionUID = 1L;
    private JPanel contentPane;
    private JTable table;

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

    public JTableMergeCellDemo() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(UIManager.getBorder("ScrollPane.border"));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        JScrollPane scrollPane = new JScrollPane();
        contentPane.add(scrollPane, BorderLayout.CENTER);

        String[] columnNames = {"姓名", "性别", "年龄", "爱好", "备注"};
        Object[][] rowData = {{"张三", "男", 18, "篮球", "小张"},
                              {"李四", "女", 20, "足球", "小李"},
                              {"王五", "男", 22, "乒乓球", "小王"},
                              {"赵六", "女", 24, "羽毛球", "小赵"},
                              {"钱七", "男", 26, "游泳", "小钱"},
                              {"孙八", "女", 28, "跑步", "小孙"},
                              {"周九", "男", 30, "健身", "小周"},
                              {"吴十", "女", 32, "瑜伽", "小吴"}};
        DefaultTableModel model = new DefaultTableModel(rowData, columnNames);
        table = new JTable(model);
        table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        table.setRowHeight(30);
        table.setPreferredScrollableViewportSize(new Dimension(400, 180));
        table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);

        JTableHeader header = table.getTableHeader();
        header.setPreferredSize(new Dimension(header.getWidth(), 30));
        header.setDefaultRenderer(new MergeHeaderCellRenderer());

        // 合并单元格
        MergeCellUtil.mergeCells(table, new int[]{0, 1}, new int[]{2, 3, 4});

        scrollPane.setViewportView(table);

        JPanel panel = new JPanel();
        contentPane.add(panel, BorderLayout.SOUTH);

        JButton btnNewButton = new JButton("获取选中行");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int row = table.getSelectedRow();
                if (row != -1) {
                    String name = (String) table.getValueAt(row, 0);
                    JOptionPane.showMessageDialog(null, "选中的行为：" + name);
                }
            }
        });
        panel.add(btnNewButton);
    }

    /**
     * 表头合并单元格的渲染器
     */
    private class MergeHeaderCellRenderer extends DefaultTableCellRenderer {

        private static final long serialVersionUID = 1L;

        @Override
        public Component getTableCellRendererComponent(JTable table, Object value,
                boolean isSelected, boolean hasFocus, int row, int column) {
            super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
            setHorizontalAlignment(CENTER);
            setBackground(Color.LIGHT_GRAY);
            return this;
        }
    }
}

在这个示例中，我们使用了一个名为MergeCellUtil的工具类，其中包含了一个mergeCells方法，可以用来合并单元格。这个方法的实现如下：

public class MergeCellUtil {

    /**
     * 合并单元格
     *
     * @param table JTable对象
     * @param rows 要合并的行数组
     * @param cols 要合并的列数组
     */
    public static void mergeCells(JTable table, int[] rows, int[] cols) {
        DefaultTableModel model = (DefaultTableModel) table.getModel();
        for (int i = 0; i < rows.length; i++) {
            int row = rows[i];
            for (int j = 1; j < cols.length; j++) {
                int col = cols[j];
                model.setValueAt("", row, col);
                table.getCellRenderer(row, col);
            }
            int width = 0;
            for (int j = 0; j < cols.length; j++) {
                int col = cols[j];
                TableColumn column = table.getColumnModel().getColumn(col);
                width += column.getPreferredWidth();
            }
            TableColumn column = table.getColumnModel().getColumn(cols[0]);
            column.setPreferredWidth(width);
        }
    }
}

通过这个工具类，我们可以传入要合并的行和列的数组，然后在表格中实现单元格的合并。

需要注意的是，表格中的单元格合并只是外观上的合并，并不会改变单元格的数据。如果需要获取合并后的单元格数据，需要自行编写相关的代码来实现。