package com.han;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.PlainDocument;
/**
* Customized fields can easily be created by extending the model
* and changing the default model provided. For example,
* the following piece of code will create a field that holds only
* digit characters. It will work even if text is pasted into from
* the clipboard or it is altered via programmatic changes.
* @author HAN
*
*/
public class DigitOnlyField extends JTextField {
/**
*
*/
private static final long serialVersionUID = 8384787369612949227L;
public DigitOnlyField(int cols) {
// super() 可以被自动调用，但是有参构造方法并不能被自动调用，只能依赖
// super关键字显示地调用父类的构造方法
super(cols);
} www.2cto.com
protected Document createDefaultModel() {
return new UpperCaseDocument();
}
static class UpperCaseDocument extends PlainDocument {
/**
*
*/
private static final long serialVersionUID = -4170536906715361215L;
public void insertString(int offs, String str, AttributeSet a)
throws BadLocationException {
if (str == null) {
return;
}
char[] upper = str.toCharArray();
String filtered = "";
for (int i = 0; i < upper.length; i++) {
if (Character.isDigit(Character.codePointAt(upper, i))){
filtered += upper[i];
}
}
super.insertString(offs, filtered, a);
}
}
}
作者：Gaowen_HAN