Flutter控制TextFild输入框只能输入小数点后两位

1.工具类

class PrecisionLimitFormatter extends TextInputFormatter {
  int _scale;

  PrecisionLimitFormatter(this._scale);

  RegExp exp = new RegExp("[0-9.]");
  static const String POINTER = ".";
  static const String DOUBLE_ZERO = "00";

  @override
  TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
    if (newValue.text.startsWith(POINTER) && newValue.text.length == 1) {
      //第一个不能输入小数点
      return oldValue;
    }

    ///输入完全删除
    if (newValue.text.isEmpty) {
      return TextEditingValue();
    }

    ///只允许输入小数
    if (!exp.hasMatch(newValue.text)) {
      return oldValue;
    }

    ///包含小数点的情况
    if (newValue.text.contains(POINTER)) {
      ///包含多个小数
      if (newValue.text.indexOf(POINTER) != newValue.text.lastIndexOf(POINTER)) {
        return oldValue;
      }
      String input = newValue.text;
      int index = input.indexOf(POINTER);

      ///小数点后位数
      int lengthAfterPointer = input.substring(index, input.length).length - 1;

      ///小数位大于精度
      if (lengthAfterPointer > _scale) {
        return oldValue;
      }
    } else if (newValue.text.startsWith(POINTER) || newValue.text.startsWith(DOUBLE_ZERO)) {
      ///不包含小数点,不能以“00”开头
      return oldValue;
    }
    return newValue;
  }
}

2.使用

TextField(
   controller: _controller,
    style: Fonts.normalTitle48Style,
    keyboardType: TextInputType.numberWithOptions(decimal: true),
    maxLength: 10,
    inputFormatters: [PrecisionLimitFormatter(2)],
    decoration: InputDecoration(
      counterText: "",
      hintText: "输入提现金额",
      hintStyle: Fonts.normalA8Grey48Style,
      border: InputBorder.none,
    ),
)