Question

正如你可以从标题中读到的，我在组织/解决一个小问题时遇到了一些麻烦。为密码字段写了一堂课。我基本上想在passwordfield中插入一个占位符，当用户点击密码字段以显示该字段实际上是密码时，它会将提示（如果你愿意）或默认文本设置为零。

想要为小项目构建登录框架。任何答案都表示赞赏。

问题包含不知道如何在用户点击时将默认文本（密码文本）剪切为零

 import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;

import javax.swing.JPasswordField;
import javax.swing.JTextField;

@SuppressWarnings("serial")
public class externPlaceholderPasswordField extends JPasswordField
{
    private String pw;
    public externPlaceholderPasswordField(String pw)
    {
        this.pw = pw;

    }


    public char[] getPassword()
    {

        char[] password = super.getPassword();

        if(password.trim().length() == 0 && pw != null)
        {

            password = pw;
        }
        return password;
    }
    @Override
    public void paintComponent(Graphics g)
    {
        setHorizontalAlignment(externPlaceholderTextField.CENTER);
        super.paintComponent(g);

    if (super.getPassword().length() > 0 || pw == null)
    {
        return;
    }
    Graphics2D g2 = (Graphics2D) g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    g2.setColor(Color.lightGray);
    g2.drawString(pw, getInsets().left, g.getFontMetrics().getMaxAscent() + getInsets().top);
}
}

PasswordField的Java Swing占位符

0 个答案: