如何设置Unicode字符是不可读的？

Question

我使用JTextArea打开了一个文件，并将文本替换为某些Unicode字符，但这些字符是可读的。问题是如何设置那些字符不可读，复制和粘贴以及何时选择符号未出现的文字？

   String previous=textArea.getText();
    if(button.isSelected()){
        previous=previous.replaceAll(" ","\u00b7");
        previous=previous.replaceAll("\t","\u00BB\t");
        textArea.setText(previous.replaceAll("\n", "\u00B6\n"));
    }

Answer 1

使用Font.canDisplayUpTo(String)检查文本区域的字体是否可以显示给定String中的所有字符。

以下是一个使用示例：

import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;

public class UnicodeCharacterTest {

    private JComponent ui = null;
    String s = new String(
            new String(Character.toChars(182)) + " "
            + new String(Character.toChars(183)) + " "
            + new String(Character.toChars(186)));

    UnicodeCharacterTest() {
        initUI();
    }

    public void initUI() {
        if (ui != null) {
            return;
        }

        ui = new JPanel(new GridLayout(0, 2));
        ui.setBorder(new EmptyBorder(4, 4, 4, 4));

        GraphicsEnvironment ge
                = GraphicsEnvironment.getLocalGraphicsEnvironment();
        Font[] fonts = ge.getAllFonts();
        for (Font font : fonts) {
            if (font.canDisplayUpTo(s)<0) {
                ui.add(new JLabel(font.getName()));
                JLabel output = new JLabel(s);
                output.setFont(font.deriveFont(24f));
                ui.add(output);
            }
        }
    }

    public JComponent getUI() {
        return ui;
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(
                            UIManager.getSystemLookAndFeelClassName());
                } catch (Exception useDefault) {
                }
                UnicodeCharacterTest o = new UnicodeCharacterTest();

                JFrame f = new JFrame("Font/Unicode test");
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                f.setLocationByPlatform(true);

                f.setContentPane(new JScrollPane(
                        o.getUI(), 
                        JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, 
                        JScrollPane.HORIZONTAL_SCROLLBAR_NEVER));
                f.pack();
                f.setSize(new Dimension(f.getSize().width,200));
                f.setMinimumSize(f.getSize());

                f.setVisible(true);
            }
        };
        SwingUtilities.invokeLater(r);
    }
}