Flutter实战技巧之-TextField限制输入整数位数和小数位数

方法比较简单，新建一个类继承**TextInputFormatter**类，重写**formatEditUpdate**方法

import 'package:flutter/services.dart';class NumLengthInputFormatter extends TextInputFormatter {  int decimalLength;  int integerLength;  bool allowInputDecimal;  NumLengthInputFormatter({this.decimalLength = 2, this.integerLength = 8}) : super();  @override  TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {    String value = newValue.text;    int selectionIndex = newValue.selection.end;    if (newValue.text.contains('.')) {      int pointIndex = newValue.text.indexOf('.');      String beforePoint = newValue.text.substring(0, pointIndex);      print('$beforePoint');      //小数点前内容大于integerLength      if (beforePoint.length > integerLength) {        value = oldValue.text;        selectionIndex = oldValue.selection.end;      } else      //小数点前内容小于等于integerLength      {        String afterPoint = newValue.text.substring(pointIndex + 1, newValue.text.length);        if (afterPoint.length > decimalLength) {          value = oldValue.text;          selectionIndex = oldValue.selection.end;        }      }    } else {      if (newValue.text.length > integerLength) {        value = oldValue.text;        selectionIndex = oldValue.selection.end;      }    }    return new TextEditingValue(      text: value,      selection: new TextSelection.collapsed(offset: selectionIndex),    );  }}

使用 限制整数位数为8位，小数位数为2位

TextField(  inputFormatters: [    NumLengthInputFormatter(decimalLength: 8, integerLength: 2)  ],),