Question

我想在java中开发一个搜索栏但是在每个键发布事件之后我想在表中而不是列表中显示建议，因为我想从数据库中显示两列作为建议。

Answer 1

有许多带有组合框的解决方案，但我希望将表格作为弹出窗口来显示建议。

您是一个显示两列数据的组合框。例如：

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.text.*;

public class ComboBoxMultiColumn extends JFrame
{
    public ComboBoxMultiColumn()
    {
        getContentPane().setLayout( new GridLayout(0, 2) );

        Vector items = new Vector();
        items.addElement( new Item("123456789", "Car" ) );
        items.addElement( new Item("23", "Plane" ) );
        items.addElement( new Item("345", "Train" ) );
        items.addElement( new Item("4567", "Nuclear Submarine" ) );

        //  Use a JTextArea as a renderer

        JComboBox comboBox1 = new JComboBox( items );
        comboBox1.setRenderer( new TextAreaRenderer(5) );

        getContentPane().add( new JLabel("TextArea Renderer") );
        getContentPane().add( comboBox1 );

        //  Use a JTextPane as a renderer

        JComboBox comboBox2 = new JComboBox( items );
        comboBox2.setRenderer( new TextPaneRenderer(10) );

        getContentPane().add( new JLabel("TextPane Renderer") );
        getContentPane().add( comboBox2 );

        //  Use a JPanel as a renderer

        JComboBox comboBox3 = new JComboBox( items );
        comboBox3.setRenderer( new PanelRenderer(50) );

        getContentPane().add( new JLabel("Panel Renderer") );
        getContentPane().add( comboBox3 );

        //  Using HTML

        JComboBox comboBox4 = new JComboBox( items );
        comboBox4.setRenderer( new HTMLRenderer() );

        getContentPane().add( new JLabel("HTML Renderer") );
        getContentPane().add( comboBox4 );
    }

    class Item
    {
        private String id;
        private String description;

        public Item(String id, String description)
        {
            this.id = id;
            this.description = description;
        }

        public String getId()
        {
            return id;
        }

        public String getDescription()
        {
            return description;
        }

        public String toString()
        {
            return description;
        }
    }

    public static void main(String[] args)
    {
        JFrame frame = new ComboBoxMultiColumn();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.pack();
        frame.setVisible( true );
    }

    /*
    **  Tabs are easier to use in a JTextArea, but not very flexible
    */
    class TextAreaRenderer extends JTextArea implements ListCellRenderer
    {
        public TextAreaRenderer(int tabSize)
        {
            setTabSize(tabSize);
        }

        public Component getListCellRendererComponent(JList list, Object value,
            int index, boolean isSelected, boolean cellHasFocus)
        {
            Item item = (Item)value;
            setText(item.getId() + "\t" + item.getDescription());
            setBackground(isSelected ? list.getSelectionBackground() : null);
            setForeground(isSelected ? list.getSelectionForeground() : null);
            return this;
        }
    }

    /*
    **  Tabs are harder to use in a JTextPane, but much more flexible
    */
    class TextPaneRenderer extends JTextPane implements ListCellRenderer
    {
        public TextPaneRenderer(int tabColumn)
        {
            setMargin( new Insets(0, 0, 0, 0) );

            FontMetrics fm = getFontMetrics( getFont() );
            int width = fm.charWidth( 'w' ) * tabColumn;

            TabStop[] tabs = new TabStop[1];
            tabs[0] = new TabStop( width, TabStop.ALIGN_LEFT, TabStop.LEAD_NONE );
            TabSet tabSet = new TabSet(tabs);

            SimpleAttributeSet attributes = new SimpleAttributeSet();
            StyleConstants.setTabSet(attributes, tabSet);
            getStyledDocument().setParagraphAttributes(0, 0, attributes, false);
        }

        public Component getListCellRendererComponent(JList list, Object value,
            int index, boolean isSelected, boolean cellHasFocus)
        {
            Item item = (Item)value;

            if (index == -1)
                setText( item.getDescription() );
            else
                setText(item.getId() + "\t" + item.getDescription());

            setBackground(isSelected ? list.getSelectionBackground() : null);
            setForeground(isSelected ? list.getSelectionForeground() : null);
            return this;
        }
    }

    /*
    **  Use a panel to hold multiple components
    */
    class PanelRenderer implements ListCellRenderer
    {
        private JPanel renderer;
        private JLabel first;
        private JLabel second;

        public PanelRenderer(int firstColumnWidth)
        {
            renderer = new JPanel();
            renderer.setLayout(new BoxLayout(renderer, BoxLayout.X_AXIS) );

            first = new JLabel(" ");
            Dimension d = first.getPreferredSize();
            d.width = firstColumnWidth;
            first.setMaximumSize(d);
            second = new JLabel();
            renderer.add(first);
            renderer.add(second);
        }

        public Component getListCellRendererComponent(JList list, Object value,
            int index, boolean isSelected, boolean cellHasFocus)
        {
            Item item = (Item)value;

            first.setText( item.getId() );
            second.setText( item.getDescription() );

            renderer.setBackground(isSelected ? list.getSelectionBackground() : null);
            renderer.setForeground(isSelected ? list.getSelectionForeground() : null);

            return renderer;
        }
    }

    /*
    **  Use HTML to format the text
    */
    class HTMLRenderer extends DefaultListCellRenderer
    {
        private static final String START = "<html><table><tr><td width=40>";
        private static final String MIDDLE = "</td><td width=120>";
        private static final String END = "</td></tr></table></html>";

        public Component getListCellRendererComponent(JList list, Object value,
            int index, boolean isSelected, boolean cellHasFocus)
        {
            super.getListCellRendererComponent(
                list, value, index, isSelected, cellHasFocus);

            Item item = (Item)value;
            setText(START
                + item.getId()
                + MIDDLE
                + item.getDescription()
                + END);

            return this;
        }
    }

}

如何为搜索栏开发下拉列表？

1 个答案: