JTable 不断调用自定义单元格渲染器方法... [英] JTable Calls Custom Cell Renderer Method... Continuously

问题描述

可在以下位置找到可编译源:http://www.splashcd.com/jtable.tar

Compilable source can be found at: http://www.splashcd.com/jtable.tar

我是该语言的新手，所以我不确定这是否可以接受.

I'm new to the language, so I'm not sure if this is acceptable behavior or not.

我创建了一个 JTable 来为收到的每条消息显示一行(它收到大约每 20 秒一次).表列之一可以包含大量文本，所以我创建了一个自定义单元格渲染器，它会自动换行并设置行相应的高度.

I created a JTable to display a row for each message received (it receives about one every 20 seconds). One of the table columns can contain a large amount of text, so I created a custom cell renderer which word wraps and sets the row height accordingly.

所有一切都按预期工作，除了一旦表格显示其第一行，它每秒调用单元格渲染器大约十次......直到用户关闭表.

All that works as expected, except that once the table displays its first row, it calls the cell renderer about ten times a second... until the user closes the table.

一旦我在那里得到大约 20 行，桌子就会变得相当缓慢，需要 2-8调整列大小、向上或向下滚动或使用选择的背景颜色.

Once I get approx 20 rows in there, the table gets fairly sluggish, taking 2-8 seconds to resize a column, scoll up or down, or render a selected row with the selected background color.

我在渲染器中插入了一个打印语句，所以我可以看到多少次正在调用 getTableCellRendererComponent 方法.

I inserted a print statement inside the renderer, so I can see how many times the getTableCellRendererComponent method is being called.

我禁用了工具提示，并禁用了所有单元格编辑.我确实有一个听众添加新行或表格时，将视图滚动到最后一行调整大小.

I disabled tool tips, and disabled all cell editing. I do have a listener that scrolls the view to the last row when either a new row is added or the table is resized.

getTableCellRendererComponent 方法是否应该每秒调用几次当我只是在查看屏幕(不触摸鼠标或键盘)时?

Should the getTableCellRendererComponent method be called several times a second when I'm just viewing the screen (not touching mouse or keyboard)?

TIA

推荐答案

• aaaaach

  • aaaaach

    你需要doLayout(),

    下一级:-)，然后您也可以轻松地为JTextComponents设置最大可见行s

    next level :-), then there you can to set Maximum visible rows for JTextComponents too, with little effort

    doLayout()

    import java.awt.*;
    import javax.swing.*;
    import javax.swing.table.*;
    import javax.swing.text.*;
    //http://tips4java.wordpress.com/2008/10/26/text-utilities/
    public class AutoWrapTest {
    
        public JComponent makeUI() {
            String[] columnNames = {" Text Area Cell Renderer "};
            Object[][] data = {
                {"123456789012345678901234567890"},
                {"dddddddddddddddddddddddddddddddddddddddddddddddddddddddddx"},
                {"----------------------------------------------0"},
                {">>>>>>>>>>>>>dddddddddddddddddddddddddddddddddddddddddddddddddd"
                    + "dddddddxdddddddddddddddddddddddddddddddddddddddddddddd"
                    + "dddddddddddx>>>>>>>>>>>>>>>>>>>>>>>>>|"},
                {">>>>>>>>>>>>ddddddddddddddddddddddddddddddddddddddddddddddddddd"
                    + "ddddddx>>>>>>>>>>>>>>>>>>>>>>>>>>|"},
                {"a|"},
                {">>>>>>>>bbbb>>>>>>>>>>>>>>>>>>>|"},
                {">>>>>>>>>>>>>>>>>>|"},
                {">>>>>>>>>>>>>dddddddddddddddddddddddddddddddddddddddddddddddddd"
                    + "dddddddxdddddddddddddd123456789012345678901234567890dddddd"
                    + "dddddddddddddddddddddddddddddddddddddx>>>>>>>>>>>>>>>>>>>>"
                    + ">>>>>|"},
                {">>>>>>>>>>>>>dddddddddddddd123456789012345678901234567890dddddd"
                    + "dddddddddddddddddddddddddddddddddddddxdddddddddddddd123456"
                    + "789012345678901234567890dddddddddddddddddddddddddddddddddd"
                    + "ddddd123456789012345678901234567890ddddx>>>>>>>>>>>>>>>>>>"
                    + ">>>>>>>|"},};
            TableModel model = new DefaultTableModel(data, columnNames) {
    
                private static final long serialVersionUID = 1L;
    
                @Override
                public boolean isCellEditable(int row, int column) {
                    return false;
                }
            };
            JTable table = new JTable(model) {
    
                private static final long serialVersionUID = 1L;
    
                @Override
                public void doLayout() {
                    TableColumn col = getColumnModel().getColumn(0);
                    for (int row = 0; row < getRowCount(); row++) {
                        Component c = prepareRenderer(col.getCellRenderer(), row, 0);
                        if (c instanceof JTextArea) {
                            JTextArea a = (JTextArea) c;
                            int h = getPreferredHeight(a) + getIntercellSpacing().height;
                            if (getRowHeight(row) != h) {
                                setRowHeight(row, h);
                            }
                        }
                    }
                    super.doLayout();
                }
    
                private int getPreferredHeight(JTextComponent c) {
                    Insets insets = c.getInsets();
                    View view = c.getUI().getRootView(c).getView(0);
                    int preferredHeight = (int) view.getPreferredSpan(View.Y_AXIS);
                    return preferredHeight + insets.top + insets.bottom;
                }
            };
            table.setEnabled(false);
            table.setShowGrid(false);
            table.setTableHeader(null);
            table.getColumnModel().getColumn(0).setCellRenderer(new TextAreaCellRenderer());
            //table.setPreferredScrollableViewportSize(table.getPreferredSize());
            JScrollPane sp = new JScrollPane(table);
            sp.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
            sp.setPreferredSize(new Dimension(250, 533));
            JPanel p = new JPanel(new BorderLayout());
            p.add(sp);
            return p;
        }
    
        public static void main(String[] args) {
            EventQueue.invokeLater(new Runnable() {
    
                @Override
                public void run() {
                    createAndShowGUI();
                }
            });
        }
    
        public static void createAndShowGUI() {
            JFrame f = new JFrame();
            f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
            f.getContentPane().add(new AutoWrapTest().makeUI());
            f.setLocation(100, 100);
            f.pack();
            f.setVisible(true);
        }
    }
    
    class TextAreaCellRenderer extends JTextArea implements TableCellRenderer {
    
        private static final long serialVersionUID = 1L;
        private final Color evenColor = new Color(230, 240, 255);
    
        public TextAreaCellRenderer() {
            super();
            setLineWrap(true);
            setBorder(BorderFactory.createEmptyBorder(2, 2, 2, 2));
        }
    
        @Override
        public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
            if (isSelected) {
                setForeground(table.getSelectionForeground());
                setBackground(table.getSelectionBackground());
            } else {
                setForeground(table.getForeground());
                setBackground(table.getBackground());
                setBackground((row % 2 == 0) ? evenColor : getBackground());
            }
            setFont(table.getFont());
            setText((value == null) ? "" : value.toString());
            return this;
        }
    }
    

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