java - 以编程方式填充 JPasswordField 而不创建 String 对象

Question

是否有一种简单的方法可以填充 JPasswordField 的文档，而无需创建包含密码的 String 对象？

我试图创建一个“更改密码”对话框，该对话框接受旧密码并要求输入新密码两次(三个密码字段)，其中旧密码可能事先已知，具体取决于用户的方式配置此(密码可能已被存储)。因此，我不想每次向用户显示相关对话框时都要求用户输入现有密码，而是想以编程方式填写它。

请注意，JPasswordField.setText(String) 和 String 构造函数不是一个选项。我想使用 char 数组来执行此操作。

我一直在尝试滥用GapContent，它似乎被PlainDocument使用，但它似乎不起作用(字符在那里，但字段已损坏):

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JFrame;
import javax.swing.JPasswordField;
import javax.swing.text.PlainDocument;
import javax.swing.SwingUtilities;
import javax.swing.text.GapContent;

public class FillJPasswordField extends JFrame {

    private JPasswordField pass;

    public FillJPasswordField() {
        setLayout(new GridBagLayout());
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        char[] password = new char[]{'p', 'a', 's', 's', 'w', 'o', 'r', 'd'};
        PlainDocument doc = new PlainDocument(new MyGapContent(password));

        pass = new JPasswordField(doc, null, 20);

        // see if the password is in there
        System.out.println(new String(pass.getPassword()));

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.weightx = 1.0d;
        gbc.insets = new Insets(10, 5, 10, 5);

        add(pass, gbc);

        pack();
        setLocationRelativeTo(null);
    }

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

            public void run() {
                new FillJPasswordField().setVisible(true);
            }
        });
    }

    private class MyGapContent extends GapContent {

        public MyGapContent() {
            super();
        }

        public MyGapContent(int initialLength) {
            super(initialLength);
        }

        public MyGapContent(char[] content) {
            this(content.length);
            replace(0, 0, content, content.length);
        }

    }
}

Answer 1

嗯..以下似乎有效:

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JFrame;
import javax.swing.JPasswordField;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.GapContent;
import javax.swing.text.PlainDocument;

public class FillJPasswordField extends JFrame {

    private JPasswordField pass;

    public FillJPasswordField() {
        setLayout(new GridBagLayout());
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        char[] password = new char[]{'p', 'a', 's', 's', 'w', 'o', 'r', 'd'};

        MyGapContent content = new MyGapContent();
        PlainDocument doc = new PlainDocument(content);
        try {
            content.insertChars(0, password);
        } catch (BadLocationException ex) {
        }
        pass = new JPasswordField(20);
        pass.setDocument(doc);

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.anchor = GridBagConstraints.PAGE_START;
        gbc.weightx = 1.0d;
        gbc.insets = new Insets(10, 5, 10, 5);
        add(pass, gbc);

        System.out.println(new String(pass.getPassword()));

        pack();
        setLocationRelativeTo(null);
    }

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

            public void run() {
                new FillJPasswordField().setVisible(true);
            }
        });
    }

    private class MyGapContent extends GapContent {

        public MyGapContent() {
            super();
        }

        public MyGapContent(int initialLength) {
            super(initialLength);
        }

        public void insertChars(int where, char[] chars) throws BadLocationException {
            if (where > length() || where < 0) {
                throw new BadLocationException("Invalid insert", length());
            }
            replace(where, 0, chars, chars.length);
        }
    }
}

以前的代码似乎不喜欢我在 MyGapContent 的构造函数内调用 replace 的事实。也许它需要按某种顺序完成操作。