使用jtextfield和jpopupmenu实现自动完成

2 回答

• 0

  我个人建议使用弹出窗口或自定义 JWindow 而不是 JPopupMenu ，因为后者最初仅用于显示菜单项 . 它通常用于其他事情，但不是以不同方式使用它的最佳实践 .

  例如，您的示例中有一些菜单项作为自动完成选项 - 如果只有一些结果，则可以正常工作 . 但是，如果有10个呢？怎么样50？还是500？您将不得不以某种方式为这些情况创建其他变通方法 - 将项目放入滚动窗格（哦，上帝，这看起来很难看）或将结果剪切到最佳状态（这也不是最好的选项） .

  所以我用 JWindow 做了一个小例子作为 AutocompleteField 的弹出窗口 . 这很简单，但是你可以从中得到一些基本的东西以及你提到的东西：

  import javax.swing.*;
  import javax.swing.border.EmptyBorder;
  import javax.swing.event.DocumentEvent;
  import javax.swing.event.DocumentListener;
  import java.awt.*;
  import java.awt.event.FocusEvent;
  import java.awt.event.FocusListener;
  import java.awt.event.KeyEvent;
  import java.awt.event.KeyListener;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  
  /**
   * @author Mikle Garin
   * @see https://stackoverflow.com/questions/45439231/implementing-autocomplete-with-jtextfield-and-jpopupmenu
   */
  
  public final class AutocompleteField extends JTextField implements FocusListener, DocumentListener, KeyListener
  {
      /**
       * {@link Function} for text lookup.
       * It simply returns {@link List} of {@link String} for the text we are looking results for.
       */
      private final Function<String, List<String>> lookup;
  
      /**
       * {@link List} of lookup results.
       * It is cached to optimize performance for more complex lookups.
       */
      private final List<String> results;
  
      /**
       * {@link JWindow} used to display offered options.
       */
      private final JWindow popup;
  
      /**
       * Lookup results {@link JList}.
       */
      private final JList list;
  
      /**
       * {@link #list} model.
       */
      private final ListModel model;
  
      /**
       * Constructs {@link AutocompleteField}.
       *
       * @param lookup {@link Function} for text lookup
       */
      public AutocompleteField ( final Function<String, List<String>> lookup )
      {
          super ();
          this.lookup = lookup;
          this.results = new ArrayList<> ();
  
          final Window parent = SwingUtilities.getWindowAncestor ( this );
          popup = new JWindow ( parent );
          popup.setType ( Window.Type.POPUP );
          popup.setFocusableWindowState ( false );
          popup.setAlwaysOnTop ( true );
  
          model = new ListModel ();
          list = new JList ( model );
  
          popup.add ( new JScrollPane ( list )
          {
              @Override
              public Dimension getPreferredSize ()
              {
                  final Dimension ps = super.getPreferredSize ();
                  ps.width = AutocompleteField.this.getWidth ();
                  return ps;
              }
          } );
  
          addFocusListener ( this );
          getDocument ().addDocumentListener ( this );
          addKeyListener ( this );
      }
  
      /**
       * Displays autocomplete popup at the correct location.
       */
      private void showAutocompletePopup ()
      {
          final Point los = AutocompleteField.this.getLocationOnScreen ();
          popup.setLocation ( los.x, los.y + getHeight () );
          popup.setVisible ( true );
      }
  
      /**
       * Closes autocomplete popup.
       */
      private void hideAutocompletePopup ()
      {
          popup.setVisible ( false );
      }
  
      @Override
      public void focusGained ( final FocusEvent e )
      {
          SwingUtilities.invokeLater ( () -> {
              if ( results.size () > 0 )
              {
                  showAutocompletePopup ();
              }
          } );
      }
  
      private void documentChanged ()
      {
          SwingUtilities.invokeLater ( () -> {
              // Updating results list
              results.clear ();
              results.addAll ( lookup.apply ( getText () ) );
  
              // Updating list view
              model.updateView ();
              list.setVisibleRowCount ( Math.min ( results.size (), 10 ) );
  
              // Selecting first result
              if ( results.size () > 0 )
              {
                  list.setSelectedIndex ( 0 );
              }
  
              // Ensure autocomplete popup has correct size
              popup.pack ();
  
              // Display or hide popup depending on the results
              if ( results.size () > 0 )
              {
                  showAutocompletePopup ();
              }
              else
              {
                  hideAutocompletePopup ();
              }
          } );
      }
  
      @Override
      public void focusLost ( final FocusEvent e )
      {
          SwingUtilities.invokeLater ( this::hideAutocompletePopup );
      }
  
      @Override
      public void keyPressed ( final KeyEvent e )
      {
          if ( e.getKeyCode () == KeyEvent.VK_UP )
          {
              final int index = list.getSelectedIndex ();
              if ( index != -1 && index > 0 )
              {
                  list.setSelectedIndex ( index - 1 );
              }
          }
          else if ( e.getKeyCode () == KeyEvent.VK_DOWN )
          {
              final int index = list.getSelectedIndex ();
              if ( index != -1 && list.getModel ().getSize () > index + 1 )
              {
                  list.setSelectedIndex ( index + 1 );
              }
          }
          else if ( e.getKeyCode () == KeyEvent.VK_ENTER )
          {
              final String text = ( String ) list.getSelectedValue ();
              setText ( text );
              setCaretPosition ( text.length () );
          }
          else if ( e.getKeyCode () == KeyEvent.VK_ESCAPE )
          {
              hideAutocompletePopup ();
          }
      }
  
      @Override
      public void insertUpdate ( final DocumentEvent e )
      {
          documentChanged ();
      }
  
      @Override
      public void removeUpdate ( final DocumentEvent e )
      {
          documentChanged ();
      }
  
      @Override
      public void changedUpdate ( final DocumentEvent e )
      {
          documentChanged ();
      }
  
      @Override
      public void keyTyped ( final KeyEvent e )
      {
          // Do nothing
      }
  
      @Override
      public void keyReleased ( final KeyEvent e )
      {
          // Do nothing
      }
  
      /**
       * Custom list model providing data and bridging view update call.
       */
      private class ListModel extends AbstractListModel
      {
          @Override
          public int getSize ()
          {
              return results.size ();
          }
  
          @Override
          public Object getElementAt ( final int index )
          {
              return results.get ( index );
          }
  
          /**
           * Properly updates list view.
           */
          public void updateView ()
          {
              super.fireContentsChanged ( AutocompleteField.this, 0, getSize () );
          }
      }
  
      /**
       * Sample {@link AutocompleteField} usage.
       *
       * @param args run arguments
       */
      public static void main ( final String[] args )
      {
          final JFrame frame = new JFrame ( "Sample autocomplete field" );
  
          // Sample data list
          final List<String> values = Arrays.asList ( "Frame", "Dialog", "Label", "Tree", "Table", "List", "Field" );
  
          // Simple lookup based on our data list
          final Function<String, List<String>> lookup = text -> values.stream ()
                  .filter ( v -> !text.isEmpty () && v.toLowerCase ().contains ( text.toLowerCase () ) && !v.equals ( text ) )
                  .collect ( Collectors.toList () );
  
          // Autocomplete field itself
          final AutocompleteField field = new AutocompleteField ( lookup );
          field.setColumns ( 15 );
  
          final JPanel border = new JPanel ( new BorderLayout () );
          border.setBorder ( new EmptyBorder ( 50, 50, 50, 50 ) );
          border.add ( field );
          frame.add ( border );
  
          frame.setDefaultCloseOperation ( WindowConstants.EXIT_ON_CLOSE );
          frame.pack ();
          frame.setLocationRelativeTo ( null );
          frame.setVisible ( true );
      }
  }
  

  所以在这个例子中，弹出窗口 JWindow 本身不是活动的（没有聚焦），并且由于其强制配置而无法获得焦点 . 这使我们能够将注意力集中在 JTextField 并继续打字 .

  在此示例中，我们还捕获字段中的向上/向下箭头等关键事件，以浏览自动完成结果 . 并且ENTER和ESCAPE用于接受/取消结果选择 .

  此代码也可以稍微重写以使用Swing PopupFactory 作为自动完成弹出窗口的源，但它在essense中仍然是相同的，因为 PopupFactory 使用的 HeavyWeightWindow 只是扩展 JWindow 并添加了一些设置 .

  回复于 2024-05-05T13:36:23+08:00
• 2

  最简单的解决方案是使菜单不可聚焦：

  menu.setFocusable(false);
  

  并在编辑器中处理键

  editField.addKeyListener(new KeyAdapter() {
              @Override
              public void keyPressed(KeyEvent e) {
                  if(KeyEvent.VK_DOWN == e.getKeyCode()) {
                      ...
  

  回复于 2024-05-05T13:36:23+08:00