flutter 输入时插入分隔符

每四位插入一个分隔符

import 'package:flutter/services.dart';

class DividerInputFormatter extends TextInputFormatter {
  final int rear; //第一个分割位数,后面分割位,,数
  final String pattern; //分割符

  DividerInputFormatter({this.rear = 4, this.pattern = ' '});

  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    //不含分隔符的文本
    String allTextPure = newValue.text.replaceAll(RegExp(pattern), '');
    //处理后含分隔符的文本
    String allTextDeal = '';
    //光标位置
    int cursorPosition = newValue.selection.baseOffset;
    for (int i = 0; i < allTextPure.length; i++) {
      if ((i > 0 && (i) % rear == 0) && allTextPure[i] != pattern) {
        allTextDeal = '$allTextDeal$pattern';
      }
      allTextDeal += allTextPure[i];
    }

    ///光标在文字最右侧(尾部)的情况,光标始终在最后
    if (cursorPosition >= newValue.text.length) {
      return TextEditingValue(
        text: allTextDeal,
        selection: TextSelection.collapsed(offset: allTextDeal.length),
      );
    }

    ///光标不在文字尾部的情况
    //如果原光标位置变为分割符,则说明左侧增加一位,光标也加一位
    if (allTextDeal.substring(cursorPosition - 1, cursorPosition) == pattern) {
      cursorPosition++;
    }
    return TextEditingValue(
      text: allTextDeal,
      selection: TextSelection.collapsed(offset: cursorPosition),
    );
  }
}

 手机号规则分隔符

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() => runApp(MaterialApp(home: DividerFormatterPage()));

class DividerFormatterPage extends StatelessWidget {
  const DividerFormatterPage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) => Scaffold(body: _buildBody());

  _buildBody() {
    return Padding(
      padding: EdgeInsets.symmetric(horizontal: 15, vertical: 100),
      child: TextField(
        inputFormatters: [
          DividerInputFormatter(pattern: '-'),
          FilteringTextInputFormatter.allow(RegExp(r'[0-9\s\-]')),
          LengthLimitingTextInputFormatter(13),
        ],
      ),
    );
  }
}

class DividerInputFormatter extends TextInputFormatter {
  final int first, rear; //第一个分割位数,后面分割位,,数
  final String pattern; //分割符

  DividerInputFormatter({this.first = 3, this.rear = 4, this.pattern = ' '});

  @override
  TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
    //不含分隔符的文本
    String allTextPure = newValue.text.replaceAll(RegExp(pattern), '');
    //处理后含分隔符的文本
    String allTextDeal = '';
    //光标位置
    int cursorPosition = newValue.selection.baseOffset;
    for (int i = 0; i < allTextPure.length; i++) {
      if ((i == first || (i - first) % rear == 0) && allTextPure[i] != pattern) {
        allTextDeal = '$allTextDeal$pattern';
      }
      allTextDeal += allTextPure[i];
    }

    ///光标在文字最右侧(尾部)的情况,光标始终在最后
    if (cursorPosition >= newValue.text.length) {
      return TextEditingValue(
        text: allTextDeal,
        selection: TextSelection.collapsed(offset: allTextDeal.length),
      );
    }

    ///光标不在文字尾部的情况
    //如果原光标位置变为分割符,则说明左侧增加一位,光标也加一位
    if (allTextDeal.substring(cursorPosition - 1, cursorPosition) == pattern) {
      cursorPosition++;
    }
    return TextEditingValue(
      text: allTextDeal,
      selection: TextSelection.collapsed(offset: cursorPosition),
    );
  }
}