我使用了自定义文本输入格式程序做这样的事情：

I used a custom text input formatter to do something like that :

class CustomTextInputFormatter extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    if (newValue.text.length == 0) {
      return newValue.copyWith(text: '');
    } else if (newValue.text.compareTo(oldValue.text) != 0) {
      int selectionIndexFromTheRight =
          newValue.text.length - newValue.selection.extentOffset;
      List<String> chars = newValue.text.replaceAll(' ', '').split('');
      String newString = '';
      for (int i = 0; i < chars.length; i++) {
        if (i % 3 == 0 && i != 0) newString += ' ';
        newString += chars[i];
      }

      return TextEditingValue(
        text: newString,
        selection: TextSelection.collapsed(
          offset: newString.length - selectionIndexFromTheRight,
        ),
      );
    } else {
      return newValue;
    }
  }
}

然后在您的TextField上：

Then on your TextField:

TextField(
   controller: _textController,
   keyboardType: TextInputType.number,
   inputFormatters: [CustomTextInputFormatter()],
)