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

问题描述

Compilable来源可在以下网址找到： 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，所以我不确定这是不是可接受的行为。

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来为每个收到的消息显示一行（它每20秒收到一个大约
）。其中一个表格列可以包含大量的
文本，因此我创建了一个自定义单元格渲染器，其中包含相应的行并设置行
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.

所有这一切都按预期工作，除了一旦表格显示第一行，
它会调用单元格渲染器大约每秒十次......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，表格变得相当迟缓，需要2-8
秒来调整列的大小，向上或向下scoll，或者渲染一个选定的选择了
背景颜色的行。

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print语句，所以我可以看到getBableCellRendererComponent方法的
多少次被叫。

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。我确实有一个监听器，当添加一个新行或者表是
调整大小时，
将视图滚动到最后一行。

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.

应该当我刚刚查看屏幕（不接触鼠标或键盘）时，getTableCellRendererComponent方法每秒被调用几次
？

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:-)，然后你可以设置 JTextComponents 的最大可见行 s，只需很少的努力

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

    doLayout（）

    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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