java强制JTextField仅为大写

Question

有没有一种方法可以强制JTextField中的所有用户输入在Java中都是大写的？

Answer 1

下面是DocumentFilter的一个示例。

AbstractDocument document = (AbstractDocument) textfield
                .getDocument();
        document.setDocumentFilter(new DocumentFilter() {
            @Override
            public void insertString(FilterBypass fb, int offset,
                    String string, AttributeSet attr)
                    throws BadLocationException {
                super.insertString(fb, offset, string.toUpperCase(), attr);
            }

            @Override
            public void replace(FilterBypass fb, int offset, int length,
                    String text, AttributeSet attrs)
                    throws BadLocationException {
                super.insertString(fb, offset, text.toUpperCase(), attrs);
            }

        });

Answer 2

你有两个直接的选择。您可以提供自己的文档，这是一点点工作，或提供自己的DocumentFilter

或者，你只要谷歌一下，看看你发现了什么，比如http://www.java2s.com/Code/Java/Swing-JFC/DocumentFilterthatmapslowercaseletterstouppercase.htm例如：）

Answer 3

一个完整的工作示例可能会对您有所帮助

import java.awt.Dimension;
import java.awt.FlowLayout;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;

public class UpperCasedTextFieldTester extends JFrame {
    /** */
    private static final long serialVersionUID = -4767854098431909437L;

    public UpperCasedTextFieldTester(){
        setSize(200, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new FlowLayout(FlowLayout.LEFT));

        DocumentFilter filter = new UppercaseDocumentFilter();

        JTextField firstName = new JTextField();
        firstName.setPreferredSize(new Dimension(100, 20));
        ((AbstractDocument) firstName.getDocument()).setDocumentFilter(filter);

        JTextField lastName = new JTextField();
        lastName.setPreferredSize(new Dimension(100, 20));
        ((AbstractDocument) lastName.getDocument()).setDocumentFilter(filter);

        add(firstName);
        add(lastName);
    }

    public static void main(String[] args) {
        new UpperCasedTextFieldTester().setVisible(true);
    }

}

class UppercaseDocumentFilter extends DocumentFilter {
    public void insertString(DocumentFilter.FilterBypass fb, int offset,
            String text, AttributeSet attr) throws BadLocationException {

        fb.insertString(offset, text.toUpperCase(), attr);
    }

    public void replace(DocumentFilter.FilterBypass fb, int offset, int length,
            String text, AttributeSet attrs) throws BadLocationException {

        fb.replace(offset, length, text.toUpperCase(), attrs);
    }
}