如何使JTextField的一部分不可编辑 [英] How to make part of a JTextField uneditable

问题描述

我想开发一个类似于IDLE的类似于控制台的界面.这涉及确定如何防止JTextField中的文本的某些部分被编辑.例如:

I wanted to develop a console-like interface, similar to IDLE. That involved determining how to prevent a certain part of the text in a JTextField from being edited. For example:

>>> help

其中">>>"不可编辑.插入符号一定不能移到某个位置的后面，并且该位置后面的文本不能以任何方式进行编辑.

Where the ">>> " is uneditable. The caret must never move behind a certain position, and the text behind that position cannot be edited in any way.

推荐答案

我看过NavigationFilter，但它似乎并不能阻止键盘驱动的插入符号的操作.

I looked at NavigationFilter, but it doesn't seem to prevent keyboard driven manipulation of the caret.

这显示了如何使用NavigationFilter做到这一点:

This shows how to do it with a NavigationFilter:

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

public class NavigationFilterPrefixWithBackspace extends NavigationFilter
{
    private int prefixLength;
    private Action deletePrevious;

    public NavigationFilterPrefixWithBackspace(int prefixLength, JTextComponent component)
    {
        this.prefixLength = prefixLength;
        deletePrevious = component.getActionMap().get("delete-previous");
        component.getActionMap().put("delete-previous", new BackspaceAction());
        component.setCaretPosition(prefixLength);
    }

    @Override
    public void setDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
    {
        fb.setDot(Math.max(dot, prefixLength), bias);
    }

    @Override
    public void moveDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
    {
        fb.moveDot(Math.max(dot, prefixLength), bias);
    }

    class BackspaceAction extends AbstractAction
    {
        @Override
        public void actionPerformed(ActionEvent e)
        {
            JTextComponent component = (JTextComponent)e.getSource();

            if (component.getCaretPosition() > prefixLength)
            {
                deletePrevious.actionPerformed( null );
            }
        }
    }

    private static void createAndShowUI()
    {
        JTextField textField = new JTextField("Prefix_", 20);
        textField.setNavigationFilter( new NavigationFilterPrefixWithBackspace(7, textField) );

        JFrame frame = new JFrame("Navigation Filter Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(textField);
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

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