Jtable，使用自定义渲染器和系统 L&F 显示排序图标 TableHeader 时出现问题

Question

我为 JTabe 标头创建了一个自定义渲染器，但对表进行排序后，当我使用默认系统 L&F（在我的情况下是 Windows 8）时，排序图标不会出现，但当我使用 Java L&F 时，图标会出现。
使用 Java L&F：

使用 L&F 系统：

这是我的类渲染器：

private class HeaderRenderer implements TableCellRenderer{
        private final LineBorder lb = new LineBorder(new Color(0, 152, 206));
        private final Dimension dim = new Dimension(150, 25);
        private TableCellRenderer delegate;

        public HeaderRenderer(TableCellRenderer delegate) {
            this.delegate = delegate;
        }

        @Override
        public Component getTableCellRendererComponent(JTable table,Object value, boolean isSelected, boolean hasFocused, int row, int column) {
            Component comp = delegate.getTableCellRendererComponent(table, value, isSelected, hasFocused, row, column);

            if (comp instanceof JLabel) {
                JLabel label = (JLabel) comp;
                label.setBackground(Color.WHITE);
                label.setPreferredSize(dim);
                label.setHorizontalAlignment(SwingConstants.CENTER);
                label.setBorder(lb);
            }

            return comp;
        }

    }

用途：

JTableHeader tableHeaderCompnoent = table.getTableHeader();
tableHeaderCompnoent.setDefaultRenderer(new HeaderRenderer(tableHeaderCompnoent.getDefaultRenderer()));

编辑：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;

import javax.swing.table.DefaultTableModel;
import javax.swing.table.JTableHeader;
import javax.swing.table.TableCellRenderer;

public class TableRenderingAndSorting extends JFrame {

    private JPanel contentPane;
    private JTable table_1;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (UnsupportedLookAndFeelException e) {
            e.printStackTrace();
        }
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    TableRenderingAndSorting frame = new TableRenderingAndSorting();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public TableRenderingAndSorting() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 497, 347);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(new BorderLayout(0, 0));

        table_1 = new JTable();
        table_1.setModel(new DefaultTableModel(
            new Object[][] {
                {"1", "Jack", "Developper"},
                {"2", "Richard", "Developper"},
                {"3", "Jassmine", "Developper"},
                {"4", "Tom", "Project leader"},
                {"5", "Anna", null},
            },
            new String[] {
                "Col1", "Col2", "Col3"
            }
        ));
        table_1.setAutoCreateRowSorter(true);
        contentPane.add(new JScrollPane(table_1), BorderLayout.CENTER);
        JTableHeader tableHeaderCompnoent = table_1.getTableHeader();
        tableHeaderCompnoent.setDefaultRenderer(new HeaderRenderer(tableHeaderCompnoent.getDefaultRenderer()));
        table_1.getTableHeader().setDefaultRenderer(new HeaderRenderer(tableHeaderCompnoent.getDefaultRenderer()));
    }

    private class HeaderRenderer implements TableCellRenderer{
        private final LineBorder lb = new LineBorder(new Color(0, 152, 206));
        private final Dimension dim = new Dimension(150, 25);
        private TableCellRenderer delegate;

        public HeaderRenderer(TableCellRenderer delegate) {
            this.delegate = delegate;
        }

        @Override
        public Component getTableCellRendererComponent(JTable table,Object value, boolean isSelected, boolean hasFocused, int row, int column) {
            Component comp = delegate.getTableCellRendererComponent(table, value, isSelected, hasFocused, row, column);

            if (comp instanceof JLabel) {
                JLabel label = (JLabel) comp;
                label.setBackground(Color.WHITE);
                label.setPreferredSize(dim);
                label.setHorizontalAlignment(SwingConstants.CENTER);
                label.setBorder(lb);
            }

            return comp;
        }

    }
}

Answer 1

[...] 当我使用默认系统 L&F（在我的例子中是 Windows 8）时，排序图标不会出现，但当我使用 Java L&F 时，图标会出现。

默认L&F（Metal）和系统L&F的区别在于，第一个将排序图标绘制在标题单元格的中心（垂直对齐），而后者将其绘制在标题单元格的顶部。

接下来发生的是为标题单元格绘制边框。边框是从组件的边缘向内绘制的，这意味着它会在组件的区域上绘制。由于排序图标位于系统 L&F 的边缘，因此它被边框覆盖。

您可以通过删除边框或将标签添加到将处理边框的

JPanel

来解决此问题：

@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocused, int row, int column) {

    Component comp = delegate.getTableCellRendererComponent(table, value, isSelected, hasFocused, row, column);
    JPanel panel = new JPanel(new BorderLayout());
    if (comp instanceof JLabel) {
        JLabel label = (JLabel) comp;
        label.setBackground(Color.WHITE);
        label.setHorizontalAlignment(SwingConstants.CENTER);
        panel.add(label);
        panel.setBorder(lb);
    }
    return panel;
}

我删除了

setPreferredSize

，正如 @mKorbel 所指出的那样，

dim

字段也应该随之删除。

另外，在行中

JTableHeader tableHeaderCompnoent = table_1.getTableHeader();
tableHeaderCompnoent.setDefaultRenderer(new HeaderRenderer(tableHeaderCompnoent.getDefaultRenderer()));
table_1.getTableHeader().setDefaultRenderer(new HeaderRenderer(tableHeaderCompnoent.getDefaultRenderer()));

第二个和第三个是一样的，你可以删除第三个。