java - 如何在我输入 JTextArea 时显示自动完成？

Question

我需要在用户输入 JTextArea 时显示建议(自动完成)，有点像手机 T9。

我不知道如何在 myTextAreaKeyTyped() 事件中执行此操作。

此应用程序是一个打字助手。它显示键盘上不存在的字符变体。 例如。您按“A”，它会显示 Â:1、Á:2、À:3……如果您按 1,2 或 3，“A”将被替换。 它已经完成，但变体显示在我的 JFrame 底部的 JLabel 中，因为我不知道如何执行此操作。

你能帮帮我吗？提前致谢。

Answer 1

这里有一个片段可以激发您的灵感。您可能需要重新组织一些代码以使其更易于维护，但它应该能为您提供要点。

基本上，我们会监听关键事件(我觉得监听文档事件不相关，例如，如果用户粘贴了一些文本，我不希望出现建议面板)，当插入符号出现时至少在 2 个字符后面，我们提出一些建议，使用包含建议的 JList 的弹出菜单(这里的建议确实没有意义，但将其绑定(bind)到字典并不难)。至于你说的捷径，做起来应该不难。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Point;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JTextArea;
import javax.swing.ListSelectionModel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.text.BadLocationException;

public class Test {

    public class SuggestionPanel {
        private JList list;
        private JPopupMenu popupMenu;
        private String subWord;
        private final int insertionPosition;

        public SuggestionPanel(JTextArea textarea, int position, String subWord, Point location) {
            this.insertionPosition = position;
            this.subWord = subWord;
            popupMenu = new JPopupMenu();
            popupMenu.removeAll();
            popupMenu.setOpaque(false);
            popupMenu.setBorder(null);
            popupMenu.add(list = createSuggestionList(position, subWord), BorderLayout.CENTER);
            popupMenu.show(textarea, location.x, textarea.getBaseline(0, 0) + location.y);
        }

        public void hide() {
            popupMenu.setVisible(false);
            if (suggestion == this) {
                suggestion = null;
            }
        }

        private JList createSuggestionList(final int position, final String subWord) {
            Object[] data = new Object[10];
            for (int i = 0; i < data.length; i++) {
                data[i] = subWord + i;
            }
            JList list = new JList(data);
            list.setBorder(BorderFactory.createLineBorder(Color.DARK_GRAY, 1));
            list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
            list.setSelectedIndex(0);
            list.addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    if (e.getClickCount() == 2) {
                        insertSelection();
                    }
                }
            });
            return list;
        }

        public boolean insertSelection() {
            if (list.getSelectedValue() != null) {
                try {
                    final String selectedSuggestion = ((String) list.getSelectedValue()).substring(subWord.length());
                    textarea.getDocument().insertString(insertionPosition, selectedSuggestion, null);
                    return true;
                } catch (BadLocationException e1) {
                    e1.printStackTrace();
                }
                hideSuggestion();
            }
            return false;
        }

        public void moveUp() {
            int index = Math.min(list.getSelectedIndex() - 1, 0);
            selectIndex(index);
        }

        public void moveDown() {
            int index = Math.min(list.getSelectedIndex() + 1, list.getModel().getSize() - 1);
            selectIndex(index);
        }

        private void selectIndex(int index) {
            final int position = textarea.getCaretPosition();
            list.setSelectedIndex(index);
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    textarea.setCaretPosition(position);
                };
            });
        }
    }

    private SuggestionPanel suggestion;
    private JTextArea textarea;

    protected void showSuggestionLater() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                showSuggestion();
            }

        });
    }

    protected void showSuggestion() {
        hideSuggestion();
        final int position = textarea.getCaretPosition();
        Point location;
        try {
            location = textarea.modelToView(position).getLocation();
        } catch (BadLocationException e2) {
            e2.printStackTrace();
            return;
        }
        String text = textarea.getText();
        int start = Math.max(0, position - 1);
        while (start > 0) {
            if (!Character.isWhitespace(text.charAt(start))) {
                start--;
            } else {
                start++;
                break;
            }
        }
        if (start > position) {
            return;
        }
        final String subWord = text.substring(start, position);
        if (subWord.length() < 2) {
            return;
        }
        suggestion = new SuggestionPanel(textarea, position, subWord, location);
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                textarea.requestFocusInWindow();
            }
        });
    }

    private void hideSuggestion() {
        if (suggestion != null) {
            suggestion.hide();
        }
    }

    protected void initUI() {
        final JFrame frame = new JFrame();
        frame.setTitle("Test frame on two screens");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel panel = new JPanel(new BorderLayout());
        textarea = new JTextArea(24, 80);
        textarea.setBorder(BorderFactory.createLineBorder(Color.DARK_GRAY, 1));
        textarea.addKeyListener(new KeyListener() {

            @Override
            public void keyTyped(KeyEvent e) {
                if (e.getKeyChar() == KeyEvent.VK_ENTER) {
                    if (suggestion != null) {
                        if (suggestion.insertSelection()) {
                            e.consume();
                            final int position = textarea.getCaretPosition();
                            SwingUtilities.invokeLater(new Runnable() {
                                @Override
                                public void run() {
                                    try {
                                        textarea.getDocument().remove(position - 1, 1);
                                    } catch (BadLocationException e) {
                                        e.printStackTrace();
                                    }
                                }
                            });
                        }
                    }
                }
            }

            @Override
            public void keyReleased(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_DOWN && suggestion != null) {
                    suggestion.moveDown();
                } else if (e.getKeyCode() == KeyEvent.VK_UP && suggestion != null) {
                    suggestion.moveUp();
                } else if (Character.isLetterOrDigit(e.getKeyChar())) {
                    showSuggestionLater();
                } else if (Character.isWhitespace(e.getKeyChar())) {
                    hideSuggestion();
                }
            }

            @Override
            public void keyPressed(KeyEvent e) {

            }
        });
        panel.add(textarea, BorderLayout.CENTER);
        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
    }

    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();
        }
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Test().initUI();
            }
        });
    }

}