Flutter 正则表达式控制TextField输入框内容

1、添加InputFormatter类继承TextInputFormatter，更加输入根据正则表达式进行匹配，匹配成功返回新的内容，不成功就不让输入

class InputFormatter extends TextInputFormatter {
  final String regExp;
  InputFormatter(this.regExp);
  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    if (newValue.text.length > 0) {
      if (RegExp(regExp).firstMatch(newValue.text) != null) {
        return newValue;
      }
      return oldValue;
    }
    return newValue;
  }
}

2、在TextField 中的inputFormatters参数中试用它

  Widget _pointsWidget() {
    String regExp = r"^((\-|\+)?(\d+)?)$";
    return Expanded(
      flex: 3,
      child: Container(
        padding: EdgeInsets.only(right: 30),
        child: TextField(
          style: TextStyle(fontSize: 15.5),
          controller: _pointsCtrl,
          inputFormatters: [InputFormatter(regExp)],
          decoration: outLineDecoration(5, isDense: true),
          keyboardType: TextInputType.number,
          onChanged: (v) {
            _countPoints();
          },
        ),
      ),
    );
  }