如上图，此类需求，身份证号码输入需要格式处理

import 'package:flutter/material.dart';class CardIdItem extends StatefulWidget {const CardIdItem({Key? key}) : super(key: key);@overrideState<CardIdItem> createState() => _CardIdItemState();
}class _CardIdItemState extends State<CardIdItem> {final TextEditingController codeEdit = TextEditingController();String _oldInputCodeText = "";@overrideWidget build(BuildContext context) {return Container(margin: const EdgeInsets.all( 20),height: 56,// color: Colors.blueAccent,child: Row(mainAxisAlignment: MainAxisAlignment.center,crossAxisAlignment: CrossAxisAlignment.center,children: <Widget>[Container(width: 70,height: 30,alignment: Alignment.centerLeft,child: const Text("身份证",style: TextStyle(fontSize: 16),),),Flexible(child: TextField(controller: codeEdit,keyboardType:  const TextInputType.numberWithOptions(signed: true),maxLength: 21,obscureText:  false,onChanged: (value) {_splitPhoneNumber(value);},style: const TextStyle(fontSize: 16),decoration: const InputDecoration(// contentPadding: EdgeInsets.only(top: 4.px),counterText: "", //此处控制最大字符是否显示hintText: "请输入身份证",hintStyle: TextStyle(color: Colors.grey),enabledBorder: UnderlineInputBorder(borderSide: BorderSide(color: Colors.grey)),focusedBorder: UnderlineInputBorder(borderSide: BorderSide(color: Colors.grey)),),),),],),);}void _splitPhoneNumber(String text) {//输入身份证号格式String codeText = getIdCode(text); //去除空格//记录此时光标位置int currentSelection = codeEdit.selection.base.offset;//删除空格，相当于删除空格前一位if (_oldInputCodeText.length > text.length &&codeText.isNotEmpty &&_oldInputCodeText.substring(currentSelection, currentSelection + 1) ==" ") {String oldStartString =_oldInputCodeText.substring(0, currentSelection + 1);//定位删除空格位置oldStartString = getIdCode(oldStartString);codeText = codeText.replaceRange(oldStartString.length - 1, oldStartString.length, "");}String newCodeText = "";for (int index = 0; index < codeText.length; index++) {if (index == 5 || index == 9 || index == 13) {newCodeText = "$newCodeText${codeText[index]} ";} else {newCodeText = newCodeText + codeText[index];}}_oldInputCodeText = newCodeText;codeEdit.text = newCodeText;if (newCodeText.length > text.length) {currentSelection = currentSelection + 1;} else if (newCodeText.length < text.length) {currentSelection = currentSelection - 1;}//设置光标位置codeEdit.selection = TextSelection.fromPosition(TextPosition(affinity: TextAffinity.downstream, offset: currentSelection));}String getIdCode(String text) {return text.replaceAll(RegExp(r"\s+\b|\b\s"), "");}
}