使用 a DocumentFilter
,这是我做的一个例子,它只接受字母字符和空格:
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.DocumentFilter.FilterBypass;
public class Test {
public Test() {
initComponents();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new Test();
}
});
}
private void initComponents() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextField jtf = new JTextField();
//add filter to document
((AbstractDocument) jtf.getDocument()).setDocumentFilter(new MyDocumentFilter());
frame.add(jtf);
frame.pack();
frame.setVisible(true);
}
}
class MyDocumentFilter extends DocumentFilter {
@Override
public void replace(FilterBypass fb, int i, int i1, String string, AttributeSet as) throws BadLocationException {
for (int n = string.length(); n > 0; n--) {//an inserted string may be more than a single character i.e a copy and paste of 'aaa123d', also we iterate from the back as super.XX implementation will put last insterted string first and so on thus 'aa123d' would be 'daa', but because we iterate from the back its 'aad' like we want
char c = string.charAt(n - 1);//get a single character of the string
System.out.println(c);
if (Character.isAlphabetic(c) || c == ' ') {//if its an alphabetic character or white space
super.replace(fb, i, i1, String.valueOf(c), as);//allow update to take place for the given character
} else {//it was not an alphabetic character or white space
System.out.println("Not allowed");
}
}
}
@Override
public void remove(FilterBypass fb, int i, int i1) throws BadLocationException {
super.remove(fb, i, i1);
}
@Override
public void insertString(FilterBypass fb, int i, String string, AttributeSet as) throws BadLocationException {
super.insertString(fb, i, string, as);
}
}