java - 如何使用 TableHeader 渲染器

Question

即使我阅读并测试了@kleopatra 的答案

• How do I correctly use customer renderers to paint specific cells in a JTable?

• particular one table header color java swing

• 关于 super.getTableCellRendererComponent(...) 必须是返回前的最后一行代码，我无法根据这些建议编写正确的渲染器，对我来说只能这样工作

• JLabel 是为 Borders、Horizo​​ntalAlignment 和 Foreground 添​​加的，尤其是 Background 使用 Component 而不是 JLabel 给我带来了一些无意义，(这里不重要)

来自 SSCCE

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;

public class SelectedTableHeader {

    private JFrame frame = new JFrame("Table Demo");
    private JTableHeader header;
    private Object selectedColumn = null;
    private String[] columnNames = {"String", "Integer", "Float", "Double", "Locale & Double", "Boolean"};
    private Object[][] data = {
        {"aaa", new Integer(12), new Float(12.15), new Double(100.05), new Double(12.05), true},
        {"bbb", new Integer(5), new Float(7.154), new Double(6.1555), new Double(417.55), false},
        {"CCC", new Integer(92), new Float(0.1135), new Double(3.1455), new Double(11.05), true},
        {"ddd", new Integer(12), new Float(31.15), new Double(10.05), new Double(23.05), true},
        {"eee", new Integer(5), new Float(5.154), new Double(16.1555), new Double(17.55), false},
        {"fff", new Integer(92), new Float(4.1135), new Double(31.1455), new Double(3.05), true}};
    private TableModel model = new DefaultTableModel(data, columnNames) {

        private static final long serialVersionUID = 1L;

        @Override
        public Class<?> getColumnClass(int column) {
            return getValueAt(0, column).getClass();
        }
    };
    private JTable table = new JTable(model);

    public SelectedTableHeader() {
        header = table.getTableHeader();
        header.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseClicked(MouseEvent e) {
                JTableHeader h = (JTableHeader) e.getSource();
                int i = h.columnAtPoint(e.getPoint());
                Object o = h.getColumnModel().getColumn(i).getHeaderValue();
                if (i < 0) {
                    selectedColumn = null;
                    return;
                }
                selectedColumn = o;
                h.requestFocusInWindow();
            }
        });
        final TableCellRenderer hr = table.getTableHeader().getDefaultRenderer();
        header.setDefaultRenderer(new TableCellRenderer() {

            private JLabel lbl;

            @Override
            public Component getTableCellRendererComponent(
                    JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
                if (selectedColumn == value) {
                    lbl = (JLabel) hr.getTableCellRendererComponent(table, value, true, true, row, column);
                    lbl.setBorder(BorderFactory.createCompoundBorder(lbl.getBorder(), BorderFactory.createLineBorder(Color.red, 1)));
                    lbl.setHorizontalAlignment(SwingConstants.LEFT);
                } else {
                    lbl = (JLabel) hr.getTableCellRendererComponent(table, value, false, false, row, column);
                    lbl.setBorder(BorderFactory.createCompoundBorder(lbl.getBorder(), BorderFactory.createEmptyBorder(0, 5, 0, 0)));
                    lbl.setHorizontalAlignment(SwingConstants.CENTER);
                }
                if (column == 0) {
                    lbl.setForeground(Color.red);
                } else {
                    lbl.setForeground(header.getForeground());
                }
                /*return (value == selectedColumn) ? hr.getTableCellRendererComponent(
                table, value, true, true, row, column) : hr.getTableCellRendererComponent(
                table, value, false, false, row, column);*/
                return lbl;
            }
        });
        table.setRowHeight(20);
        table.setPreferredScrollableViewportSize(table.getPreferredSize());
        JScrollPane scroll = new JScrollPane(table);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(scroll);
        frame.pack();
        frame.setLocation(150, 150);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                SelectedTableHeader selectedTableHeader = new SelectedTableHeader();
            }
        });
    }
}

Answer 1

根据我的经验，当您覆盖任何 JTable Renderer 时，最好获取 DefaultTableCellHeaderRenderer。因此，不是直接从 Renderer 中弄乱 JLabel，而是使用 super() 获取 Renderer。因此，您的代码应如下所示:

header.setDefaultRenderer(new DefaultTableCellHeaderRenderer() {


    @Override
    public Component getTableCellRendererComponent(
            JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
        DefaultTableCellHeaderRenderer rendererComponent = (DefaultTableCellHeaderRenderer)super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);

        if (selectedColumn == value) {
            rendererComponent.setBorder(BorderFactory.createCompoundBorder(rendererComponent.getBorder(), BorderFactory.createLineBorder(Color.red, 1)));
            rendererComponent.setHorizontalAlignment(SwingConstants.LEFT);
        } else {
            rendererComponent.setBorder(BorderFactory.createCompoundBorder(rendererComponent.getBorder(), BorderFactory.createEmptyBorder(0, 5, 0, 0)));
            rendererComponent.setHorizontalAlignment(SwingConstants.CENTER);
        }
        if (column == 0) {
            rendererComponent.setForeground(Color.red);
        } else {
            rendererComponent.setForeground(header.getForeground());
        }

        return rendererComponent;
    }
});

尝试直接回答您的问题:

问题 1:

问:如何正确使用客户渲染器绘制 JTable 中的特定单元格？

A:您当前的代码是在 JTableHeader 上设置一个 Renderer。要在您的表格单元格上添加渲染器，代码与上面类似，只是您通过 Column 模型设置它:

table.getColumnModel().getColumn(0).setCellRenderer(new DefaultTableCellRenderer() {
    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
        DefaultTableCellRenderer renderer = (DefaultTableCellRenderer)super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);

        // Set your code to render your component.

        return renderer;
    }

});

请注意:JTables 是基于列的，这意味着特定列中的所有数据必须是同一类型(您的 SSCCE 遵循此约定)。我最喜欢做的事情是为每种类型提供自定义 Renderer。例如，每当我有一个 Date 列时，我都会使用这个渲染器:

import java.awt.Component;
import javax.swing.JTable;
import javax.swing.table.DefaultTableCellRenderer;
import org.joda.time.LocalDate;

/**
 *
 * @author Ryan
 */
public class DateCellRenderer extends DefaultTableCellRenderer {

    String pattern;
    public DateCellRenderer(String pattern){
        this.pattern = pattern;
    }

    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
        DefaultTableCellRenderer renderer = (DefaultTableCellRenderer)super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
        if (value != null && value instanceof LocalDate) {
            renderer.setText(((LocalDate)value).toString(pattern));
        } else
            throw new IllegalArgumentException("Only supported Object type is LocalDate.");

        return renderer;
    }
}

我用类似的东西调用这段代码:

table.getColumn("Date Entered").setCellRenderer(new DateCellRenderer("MMM dd, yyyy"));

问题 2:

问:特定一个表头颜色java swing

A:嗯..你的 SSCCE 似乎已经弄清楚了。

问题 3:

问:关于 super.getTableCellRendererComponent(...) 必须是返回前的最后一行代码，我无法根据这些建议编写正确的渲染器，对我来说只能这样工作

答:我不确定你的意思是“必须是返回前的最后一行代码”。事实并非如此，我上面给出的代码片段证明了这一点

问题 4:

问:为 Borders、Horizo​​ntalAlignment 和 Foreground 添​​加了 JLabel，尤其是 Background 使用 Component 而不是 JLabel 给我带来了一些无意义，(这里不重要)

答:好的... DefaultTableCellHeaderRenderer 足以满足所有这些，边框、对齐、前景和背景。