java中jTextField中怎么过滤不需要的输入键

Question

自己定义一个类扩展Document接口（一般是继承PlainDocument），然后调用
JTextField.setDocument(...)

Answer 1

JDK 1.4
http://www-900.ibm.com/developerWorks/cn/java/j-merlin/part11/index.shtml1.3
class WholeNumberDocument extends PlainDocument {
        public void insertString(int offs, 
                                 String str,
                                 AttributeSet a) 
                throws BadLocationException {
            char[] source = str.toCharArray();
            char[] result = new char[source.length];
            int j = 0;            for (int i = 0; i < result.length; i++) {
                if (Character.isDigit(source[i]))
                    result[j++] = source[i];
                else {
                    toolkit.beep();
                    System.err.println("insertString: " + source[i]);
                }
            }
            super.insertString(offs, new String(result, 0, j), a);
        }
    }