Flutter CSV导入导出：大数据处理与用户体验优化

Flutter CSV导入导出：大数据处理与用户体验优化

本文基于BeeCount(蜜蜂记账)项目的实际开发经验，深入探讨如何在Flutter应用中实现高效、用户友好的CSV数据导入导出功能。

项目背景

BeeCount(蜜蜂记账)是一款开源、简洁、无广告的个人记账应用。所有财务数据完全由用户掌控，支持本地存储和可选的云端同步，确保数据绝对安全。

引言

数据的导入导出是现代应用的基本需求，特别是对于财务管理类应用。用户希望能够：

• 从其他记账软件迁移数据
• 定期备份数据到本地文件
• 在电脑上进行数据分析处理
• 与会计软件进行数据交换

CSV格式因其简单性和通用性，成为了数据交换的首选格式。但在移动端实现高效的CSV处理并不简单，需要考虑性能、内存占用、用户体验等多个方面。

CSV处理架构设计

核心组件架构

// CSV处理服务接口
abstract class CsvService {Future<CsvExportResult> exportTransactions({required int ledgerId,required DateTimeRange dateRange,required CsvExportOptions options,});Future<CsvImportResult> importTransactions({required String csvContent,required int ledgerId,required CsvImportOptions options,void Function(double progress)? onProgress,});Future<List<CsvColumn>> analyzeCsvStructure(String csvContent);
}// CSV导出选项
class CsvExportOptions {final bool includeHeader;final String separator;final String encoding;final List<String> columns;final TransactionFilter? filter;const CsvExportOptions({this.includeHeader = true,this.separator = ',',this.encoding = 'utf-8',required this.columns,this.filter,});
}// CSV导入选项
class CsvImportOptions {final bool hasHeader;final String separator;final String encoding;final Map<String, String> columnMapping;final bool skipDuplicates;final ConflictResolution conflictResolution;const CsvImportOptions({this.hasHeader = true,this.separator = ',',this.encoding = 'utf-8',required this.columnMapping,this.skipDuplicates = true,this.conflictResolution = ConflictResolution.skip,});
}// 导出结果
class CsvExportResult {final bool success;final String? filePath;final int recordCount;final String? error;const CsvExportResult({required this.success,this.filePath,required this.recordCount,this.error,});factory CsvExportResult.success({required String filePath,required int recordCount,}) {return CsvExportResult(success: true,filePath: filePath,recordCount: recordCount,);}factory CsvExportResult.failure(String error) {return CsvExportResult(success: false,error: error,recordCount: 0,);}
}// 导入结果
class CsvImportResult {final bool success;final int totalRows;final int importedRows;final int skippedRows;final List<ImportError> errors;const CsvImportResult({required this.success,required this.totalRows,required this.importedRows,required this.skippedRows,required this.errors,});
}

CSV服务实现

class CsvServiceImpl implements CsvService {final BeeRepository repository;final Logger logger;CsvServiceImpl({required this.repository,required this.logger,});@overrideFuture<CsvExportResult> exportTransactions({required int ledgerId,required DateTimeRange dateRange,required CsvExportOptions options,}) async {try {logger.info('Starting CSV export for ledger $ledgerId');// 获取交易数据final transactions = await repository.getTransactionsInRange(ledgerId: ledgerId,range: dateRange,filter: options.filter,);if (transactions.isEmpty) {return CsvExportResult.failure('没有找到符合条件的交易记录');}// 生成CSV内容final csvContent = await _generateCsvContent(transactions,options,);// 保存文件final filePath = await _saveCsvFile(csvContent,'transactions_export_${DateTime.now().millisecondsSinceEpoch}.csv',);logger.info('CSV export completed: ${transactions.length} records');return CsvExportResult.success(filePath: filePath,recordCount: transactions.length,);} catch (e, stackTrace) {logger.error('CSV export failed', e, stackTrace);return CsvExportResult.failure('导出失败: $e');}}@overrideFuture<CsvImportResult> importTransactions({required String csvContent,required int ledgerId,required CsvImportOptions options,void Function(double progress)? onProgress,}) async {try {logger.info('Starting CSV import for ledger $ledgerId');// 解析CSV内容final List<List<String>> rows = await _parseCsvContent(csvContent,options,);if (rows.isEmpty) {return CsvImportResult(success: false,totalRows: 0,importedRows: 0,skippedRows: 0,errors: [ImportError(row: 0, message: 'CSV文件为空')],);}// 处理表头int startRow = options.hasHeader ? 1 : 0;final dataRows = rows.skip(startRow).toList();// 批量导入final result = await _importRows(dataRows,ledgerId,options,onProgress,);logger.info('CSV import completed: ${result.importedRows}/${result.totalRows}');return result;} catch (e, stackTrace) {logger.error('CSV import failed', e, stackTrace);return CsvImportResult(success: false,totalRows: 0,importedRows: 0,skippedRows: 0,errors: [ImportError(row: 0, message: '导入失败: $e')],);}}Future<String> _generateCsvContent(List<TransactionWithDetails> transactions,CsvExportOptions options,) async {final StringBuffer buffer = StringBuffer();// 添加表头if (options.includeHeader) {final headers = options.columns.map((col) => _getColumnDisplayName(col));buffer.writeln(headers.join(options.separator));}// 添加数据行for (final transaction in transactions) {final row = options.columns.map((column) => _formatCellValue(_getTransactionValue(transaction, column)));buffer.writeln(row.join(options.separator));}return buffer.toString();}String _getTransactionValue(TransactionWithDetails transaction, String column) {switch (column) {case 'date':return DateFormat('yyyy-MM-dd').format(transaction.happenedAt);case 'time':return DateFormat('HH:mm:ss').format(transaction.happenedAt);case 'type':return _getTypeDisplayName(transaction.type);case 'amount':return transaction.amount.toStringAsFixed(2);case 'category':return transaction.categoryName ?? '';case 'account':return transaction.accountName ?? '';case 'toAccount':return transaction.toAccountName ?? '';case 'note':return transaction.note ?? '';default:return '';}}String _formatCellValue(String value) {// 处理包含逗号、引号、换行符的值if (value.contains(',') || value.contains('"') || value.contains('\n')) {return '"${value.replaceAll('"', '""')}"';}return value;}Future<String> _saveCsvFile(String content, String fileName) async {final directory = await getApplicationDocumentsDirectory();final file = File(path.join(directory.path, fileName));await file.writeAsString(content, encoding: utf8);return file.path;}Future<List<List<String>>> _parseCsvContent(String content,CsvImportOptions options,) async {// 使用csv包解析内容return const CsvToListConverter(fieldDelimiter: ',',textDelimiter: '"',eol: '\n',).convert(content);}Future<CsvImportResult> _importRows(List<List<String>> rows,int ledgerId,CsvImportOptions options,void Function(double progress)? onProgress,) async {int importedCount = 0;int skippedCount = 0;final List<ImportError> errors = [];// 批量处理，每次处理100行const batchSize = 100;final totalRows = rows.length;for (int i = 0; i < rows.length; i += batchSize) {final batchEnd = math.min(i + batchSize, rows.length);final batch = rows.sublist(i, batchEnd);final batchResult = await _processBatch(batch,ledgerId,options,i, // 起始行号);importedCount += batchResult.importedRows;skippedCount += batchResult.skippedRows;errors.addAll(batchResult.errors);// 更新进度if (onProgress != null) {final progress = batchEnd / totalRows;onProgress(progress);}// 让出控制权，避免阻塞UIawait Future.delayed(const Duration(milliseconds: 10));}return CsvImportResult(success: errors.isEmpty || importedCount > 0,totalRows: totalRows,importedRows: importedCount,skippedRows: skippedCount,errors: errors,);}Future<BatchImportResult> _processBatch(List<List<String>> batch,int ledgerId,CsvImportOptions options,int startRowIndex,) async {int importedCount = 0;int skippedCount = 0;final List<ImportError> errors = [];final List<Transaction> transactionsToInsert = [];for (int i = 0; i < batch.length; i++) {final rowIndex = startRowIndex + i;final row = batch[i];try {final transaction = _parseTransactionFromRow(row,ledgerId,options.columnMapping,rowIndex,);if (transaction != null) {// 检查是否跳过重复项if (options.skipDuplicates) {final exists = await repository.checkTransactionExists(ledgerId: ledgerId,amount: transaction.amount,happenedAt: transaction.happenedAt,note: transaction.note,);if (exists) {skippedCount++;continue;}}transactionsToInsert.add(transaction);importedCount++;} else {skippedCount++;}} catch (e) {errors.add(ImportError(row: rowIndex + 1,message: e.toString(),));skippedCount++;}}// 批量插入交易if (transactionsToInsert.isNotEmpty) {await repository.insertTransactionsBatch(transactionsToInsert);}return BatchImportResult(importedRows: importedCount,skippedRows: skippedCount,errors: errors,);}Transaction? _parseTransactionFromRow(List<String> row,int ledgerId,Map<String, String> columnMapping,int rowIndex,) {try {// 解析必需字段final dateStr = _getColumnValue(row, columnMapping, 'date');final amountStr = _getColumnValue(row, columnMapping, 'amount');final typeStr = _getColumnValue(row, columnMapping, 'type');if (dateStr.isEmpty || amountStr.isEmpty || typeStr.isEmpty) {throw Exception('缺少必需字段：日期、金额或类型');}// 解析日期final date = _parseDate(dateStr);if (date == null) {throw Exception('日期格式不正确：$dateStr');}// 解析金额final amount = double.tryParse(amountStr);if (amount == null || amount <= 0) {throw Exception('金额格式不正确：$amountStr');}// 解析类型final type = _parseTransactionType(typeStr);if (type == null) {throw Exception('交易类型不支持：$typeStr');}// 解析可选字段final note = _getColumnValue(row, columnMapping, 'note');final categoryName = _getColumnValue(row, columnMapping, 'category');final accountName = _getColumnValue(row, columnMapping, 'account');return Transaction(id: 0, // 将由数据库自动分配ledgerId: ledgerId,type: type,amount: amount,categoryId: await _getCategoryId(ledgerId, categoryName, type),accountId: await _getAccountId(ledgerId, accountName),happenedAt: date,note: note.isEmpty ? null : note,);} catch (e) {logger.warning('Failed to parse row $rowIndex: $e');return null;}}String _getColumnValue(List<String> row, Map<String, String> mapping, String logicalColumn) {final physicalColumn = mapping[logicalColumn];if (physicalColumn == null) return '';final columnIndex = int.tryParse(physicalColumn);if (columnIndex == null || columnIndex >= row.length) return '';return row[columnIndex].trim();}DateTime? _parseDate(String dateStr) {// 尝试多种日期格式final formats = ['yyyy-MM-dd','yyyy/MM/dd','MM/dd/yyyy','dd/MM/yyyy','yyyy-MM-dd HH:mm:ss','MM/dd/yyyy HH:mm:ss',];for (final format in formats) {try {return DateFormat(format).parse(dateStr);} catch (_) {continue;}}return null;}String? _parseTransactionType(String typeStr) {final type = typeStr.toLowerCase();switch (type) {case '支出':case 'expense':case '出':case '-':return 'expense';case '收入':case 'income':case '入':case '+':return 'income';case '转账':case 'transfer':case '转':return 'transfer';default:return null;}}
}

文件选择与预览

文件选择器实现

class CsvImportPage extends ConsumerStatefulWidget {const CsvImportPage({Key? key}) : super(key: key);@overrideConsumerState<CsvImportPage> createState() => _CsvImportPageState();
}class _CsvImportPageState extends ConsumerState<CsvImportPage> {String? _selectedFilePath;List<List<String>>? _previewData;CsvImportOptions? _importOptions;bool _isAnalyzing = false;bool _isImporting = false;double _importProgress = 0.0;@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('导入CSV'),actions: [if (_previewData != null && _importOptions != null)TextButton(onPressed: _isImporting ? null : _startImport,child: const Text('导入'),),],),body: Column(children: [if (_isImporting) _buildProgressIndicator(),Expanded(child: _selectedFilePath == null? _buildFilePicker(): _buildPreviewAndMapping(),),],),);}Widget _buildFilePicker() {return Center(child: Column(mainAxisAlignment: MainAxisAlignment.center,children: [Icon(Icons.upload_file,size: 80,color: Theme.of(context).colorScheme.primary.withOpacity(0.6),),const SizedBox(height: 24),Text('选择CSV文件',style: Theme.of(context).textTheme.headlineSmall,),const SizedBox(height: 8),Text('支持从其他记账应用导出的CSV文件',style: Theme.of(context).textTheme.bodyMedium?.copyWith(color: Theme.of(context).colorScheme.onSurfaceVariant,),textAlign: TextAlign.center,),const SizedBox(height: 32),FilledButton.icon(onPressed: _pickFile,icon: const Icon(Icons.folder_open),label: const Text('选择文件'),),const SizedBox(height: 16),TextButton.icon(onPressed: _showImportGuide,icon: const Icon(Icons.help_outline),label: const Text('导入说明'),),],),);}Widget _buildPreviewAndMapping() {return Column(children: [// 文件信息Card(margin: const EdgeInsets.all(16),child: ListTile(leading: const Icon(Icons.description),title: Text(path.basename(_selectedFilePath!)),subtitle: Text('${_previewData?.length ?? 0} 行数据'),trailing: IconButton(onPressed: _clearSelection,icon: const Icon(Icons.close),),),),// 预览和字段映射Expanded(child: DefaultTabController(length: 2,child: Column(children: [const TabBar(tabs: [Tab(text: '数据预览'),Tab(text: '字段映射'),],),Expanded(child: TabBarView(children: [_buildDataPreview(),_buildFieldMapping(),],),),],),),),],);}Widget _buildDataPreview() {if (_previewData == null || _previewData!.isEmpty) {return const Center(child: Text('无数据可预览'));}// 只显示前10行数据final previewRows = _previewData!.take(10).toList();return SingleChildScrollView(padding: const EdgeInsets.all(16),child: SingleChildScrollView(scrollDirection: Axis.horizontal,child: DataTable(columnSpacing: 20,columns: previewRows.first.asMap().entries.map((entry) {return DataColumn(label: Text('列 ${entry.key + 1}',style: Theme.of(context).textTheme.bodySmall,),);}).toList(),rows: previewRows.skip(1).map((row) {return DataRow(cells: row.map((cell) {return DataCell(Container(constraints: const BoxConstraints(maxWidth: 120),child: Text(cell,overflow: TextOverflow.ellipsis,style: Theme.of(context).textTheme.bodySmall,),),);}).toList(),);}).toList(),),),);}Widget _buildFieldMapping() {if (_previewData == null || _previewData!.isEmpty) {return const Center(child: Text('无数据可映射'));}final headers = _previewData!.first;return SingleChildScrollView(padding: const EdgeInsets.all(16),child: Column(crossAxisAlignment: CrossAxisAlignment.start,children: [Text('字段映射',style: Theme.of(context).textTheme.titleMedium,),const SizedBox(height: 8),Text('请将CSV文件的列映射到对应的交易字段',style: Theme.of(context).textTheme.bodyMedium?.copyWith(color: Theme.of(context).colorScheme.onSurfaceVariant,),),const SizedBox(height: 16),...{'date': '日期 *','amount': '金额 *','type': '类型 *','category': '分类','account': '账户','note': '备注',}.entries.map((entry) {return _buildFieldMappingRow(entry.key,entry.value,headers,);}).toList(),const SizedBox(height: 24),// 导入选项_buildImportOptions(),],),);}Widget _buildFieldMappingRow(String field,String displayName,List<String> headers,) {return Padding(padding: const EdgeInsets.symmetric(vertical: 8),child: Row(children: [SizedBox(width: 100,child: Text(displayName,style: Theme.of(context).textTheme.bodyMedium?.copyWith(fontWeight: displayName.contains('*') ? FontWeight.w600 : FontWeight.normal,),),),Expanded(child: DropdownButtonFormField<String>(value: _importOptions?.columnMapping[field],decoration: const InputDecoration(border: OutlineInputBorder(),contentPadding: EdgeInsets.symmetric(horizontal: 12, vertical: 8),),hint: const Text('选择列'),items: [const DropdownMenuItem<String>(value: null,child: Text('不映射'),),...headers.asMap().entries.map((entry) {return DropdownMenuItem<String>(value: entry.key.toString(),child: Text('列${entry.key + 1}: ${entry.value}'),);}),],onChanged: (value) {_updateFieldMapping(field, value);},),),],),);}Widget _buildImportOptions() {return Column(crossAxisAlignment: CrossAxisAlignment.start,children: [Text('导入选项',style: Theme.of(context).textTheme.titleMedium,),const SizedBox(height: 16),SwitchListTile(title: const Text('第一行为标题行'),subtitle: const Text('勾选则跳过第一行数据'),value: _importOptions?.hasHeader ?? true,onChanged: (value) {_updateImportOption('hasHeader', value);},),SwitchListTile(title: const Text('跳过重复记录'),subtitle: const Text('根据金额、日期和备注判断重复'),value: _importOptions?.skipDuplicates ?? true,onChanged: (value) {_updateImportOption('skipDuplicates', value);},),],);}Widget _buildProgressIndicator() {return Container(padding: const EdgeInsets.all(16),child: Column(children: [LinearProgressIndicator(value: _importProgress),const SizedBox(height: 8),Text('导入进度: ${(_importProgress * 100).toInt()}%',style: Theme.of(context).textTheme.bodySmall,),],),);}Future<void> _pickFile() async {try {final result = await FilePicker.platform.pickFiles(type: FileType.custom,allowedExtensions: ['csv'],allowMultiple: false,);if (result != null && result.files.isNotEmpty) {final file = result.files.first;if (file.path != null) {setState(() {_selectedFilePath = file.path;_isAnalyzing = true;});await _analyzeCsvFile();}}} catch (e) {_showErrorDialog('文件选择失败: $e');}}Future<void> _analyzeCsvFile() async {try {final file = File(_selectedFilePath!);final content = await file.readAsString();// 解析CSV预览数据final rows = const CsvToListConverter().convert(content);setState(() {_previewData = rows;_importOptions = CsvImportOptions(hasHeader: true,skipDuplicates: true,columnMapping: {},conflictResolution: ConflictResolution.skip,);_isAnalyzing = false;});// 尝试智能映射字段_attemptAutoMapping();} catch (e) {setState(() {_isAnalyzing = false;});_showErrorDialog('文件解析失败: $e');}}void _attemptAutoMapping() {if (_previewData == null || _previewData!.isEmpty) return;final headers = _previewData!.first.map((h) => h.toLowerCase()).toList();final Map<String, String> autoMapping = {};// 智能匹配字段for (int i = 0; i < headers.length; i++) {final header = headers[i];if (header.contains('日期') || header.contains('date') || header.contains('time')) {autoMapping['date'] = i.toString();} else if (header.contains('金额') || header.contains('amount') || header.contains('money')) {autoMapping['amount'] = i.toString();} else if (header.contains('类型') || header.contains('type') || header.contains('kind')) {autoMapping['type'] = i.toString();} else if (header.contains('分类') || header.contains('category')) {autoMapping['category'] = i.toString();} else if (header.contains('账户') || header.contains('account')) {autoMapping['account'] = i.toString();} else if (header.contains('备注') || header.contains('note') || header.contains('memo')) {autoMapping['note'] = i.toString();}}setState(() {_importOptions = _importOptions!.copyWith(columnMapping: autoMapping);});}void _updateFieldMapping(String field, String? columnIndex) {final newMapping = Map<String, String>.from(_importOptions!.columnMapping);if (columnIndex != null) {newMapping[field] = columnIndex;} else {newMapping.remove(field);}setState(() {_importOptions = _importOptions!.copyWith(columnMapping: newMapping);});}void _updateImportOption(String option, dynamic value) {setState(() {switch (option) {case 'hasHeader':_importOptions = _importOptions!.copyWith(hasHeader: value);break;case 'skipDuplicates':_importOptions = _importOptions!.copyWith(skipDuplicates: value);break;}});}Future<void> _startImport() async {// 验证必需字段final requiredFields = ['date', 'amount', 'type'];final missingFields = requiredFields.where((field) => !_importOptions!.columnMapping.containsKey(field),).toList();if (missingFields.isNotEmpty) {_showErrorDialog('请映射必需字段: ${missingFields.join(', ')}');return;}setState(() {_isImporting = true;_importProgress = 0.0;});try {final csvService = ref.read(csvServiceProvider);final currentLedgerId = ref.read(currentLedgerIdProvider);final file = File(_selectedFilePath!);final content = await file.readAsString();final result = await csvService.importTransactions(csvContent: content,ledgerId: currentLedgerId,options: _importOptions!,onProgress: (progress) {setState(() {_importProgress = progress;});},);setState(() {_isImporting = false;});_showImportResult(result);} catch (e) {setState(() {_isImporting = false;});_showErrorDialog('导入失败: $e');}}void _showImportResult(CsvImportResult result) {showDialog(context: context,builder: (context) => ImportResultDialog(result: result),);}void _showErrorDialog(String message) {showDialog(context: context,builder: (context) => AlertDialog(title: const Text('错误'),content: Text(message),actions: [TextButton(onPressed: () => Navigator.pop(context),child: const Text('确定'),),],),);}void _clearSelection() {setState(() {_selectedFilePath = null;_previewData = null;_importOptions = null;});}void _showImportGuide() {showDialog(context: context,builder: (context) => const ImportGuideDialog(),);}
}

导出功能实现

导出选项配置

class CsvExportPage extends ConsumerStatefulWidget {const CsvExportPage({Key? key}) : super(key: key);@overrideConsumerState<CsvExportPage> createState() => _CsvExportPageState();
}class _CsvExportPageState extends ConsumerState<CsvExportPage> {DateTimeRange _dateRange = DateTimeRange(start: DateTime.now().subtract(const Duration(days: 30)),end: DateTime.now(),);final Set<String> _selectedColumns = {'date','type','amount','category','account','note',};bool _isExporting = false;@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('导出CSV'),actions: [TextButton(onPressed: _isExporting ? null : _startExport,child: const Text('导出'),),],),body: SingleChildScrollView(padding: const EdgeInsets.all(16),child: Column(crossAxisAlignment: CrossAxisAlignment.start,children: [_buildDateRangeSelector(),const SizedBox(height: 24),_buildColumnSelector(),const SizedBox(height: 24),_buildExportOptions(),],),),);}Widget _buildDateRangeSelector() {return Card(child: Padding(padding: const EdgeInsets.all(16),child: Column(crossAxisAlignment: CrossAxisAlignment.start,children: [Text('选择时间范围',style: Theme.of(context).textTheme.titleMedium,),const SizedBox(height: 16),Row(children: [Expanded(child: _buildDateButton('开始日期',_dateRange.start,(date) {setState(() {_dateRange = DateTimeRange(start: date,end: _dateRange.end,);});},),),const SizedBox(width: 16),Expanded(child: _buildDateButton('结束日期',_dateRange.end,(date) {setState(() {_dateRange = DateTimeRange(start: _dateRange.start,end: date,);});},),),],),const SizedBox(height: 16),// 快捷选择按钮Wrap(spacing: 8,children: [_buildQuickRangeChip('最近7天', 7),_buildQuickRangeChip('最近30天', 30),_buildQuickRangeChip('最近90天', 90),_buildQuickRangeChip('本年', 365),],),],),),);}Widget _buildDateButton(String label, DateTime date, Function(DateTime) onSelected) {return OutlinedButton(onPressed: () async {final selected = await showDatePicker(context: context,initialDate: date,firstDate: DateTime(2020),lastDate: DateTime.now(),);if (selected != null) {onSelected(selected);}},child: Column(mainAxisSize: MainAxisSize.min,children: [Text(label,style: Theme.of(context).textTheme.bodySmall,),const SizedBox(height: 4),Text(DateFormat('yyyy-MM-dd').format(date),style: Theme.of(context).textTheme.bodyLarge,),],),);}Widget _buildQuickRangeChip(String label, int days) {return ActionChip(label: Text(label),onPressed: () {setState(() {_dateRange = DateTimeRange(start: DateTime.now().subtract(Duration(days: days)),end: DateTime.now(),);});},);}Widget _buildColumnSelector() {final availableColumns = {'date': '日期','time': '时间','type': '类型','amount': '金额','category': '分类','account': '账户','toAccount': '转入账户','note': '备注',};return Card(child: Padding(padding: const EdgeInsets.all(16),child: Column(crossAxisAlignment: CrossAxisAlignment.start,children: [Row(mainAxisAlignment: MainAxisAlignment.spaceBetween,children: [Text('选择导出字段',style: Theme.of(context).textTheme.titleMedium,),Row(children: [TextButton(onPressed: () {setState(() {_selectedColumns.addAll(availableColumns.keys);});},child: const Text('全选'),),TextButton(onPressed: () {setState(() {_selectedColumns.clear();});},child: const Text('清空'),),],),],),const SizedBox(height: 8),...availableColumns.entries.map((entry) {return CheckboxListTile(title: Text(entry.value),value: _selectedColumns.contains(entry.key),onChanged: (value) {setState(() {if (value ?? false) {_selectedColumns.add(entry.key);} else {_selectedColumns.remove(entry.key);}});},contentPadding: EdgeInsets.zero,);}).toList(),],),),);}Widget _buildExportOptions() {return Card(child: Padding(padding: const EdgeInsets.all(16),child: Column(crossAxisAlignment: CrossAxisAlignment.start,children: [Text('导出选项',style: Theme.of(context).textTheme.titleMedium,),const SizedBox(height: 16),SwitchListTile(title: const Text('包含表头'),subtitle: const Text('在第一行包含字段名称'),value: true,onChanged: null, // 暂时固定为truecontentPadding: EdgeInsets.zero,),ListTile(title: const Text('文件格式'),subtitle: const Text('UTF-8 编码的CSV文件'),trailing: const Text('CSV'),contentPadding: EdgeInsets.zero,),],),),);}Future<void> _startExport() async {if (_selectedColumns.isEmpty) {ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('请选择至少一个导出字段')),);return;}setState(() {_isExporting = true;});try {final csvService = ref.read(csvServiceProvider);final currentLedgerId = ref.read(currentLedgerIdProvider);final result = await csvService.exportTransactions(ledgerId: currentLedgerId,dateRange: _dateRange,options: CsvExportOptions(columns: _selectedColumns.toList(),includeHeader: true,),);setState(() {_isExporting = false;});if (result.success) {_showExportSuccess(result);} else {_showErrorDialog(result.error ?? '导出失败');}} catch (e) {setState(() {_isExporting = false;});_showErrorDialog('导出失败: $e');}}void _showExportSuccess(CsvExportResult result) {showDialog(context: context,builder: (context) => AlertDialog(title: const Text('导出成功'),content: Column(mainAxisSize: MainAxisSize.min,crossAxisAlignment: CrossAxisAlignment.start,children: [Text('已导出 ${result.recordCount} 条记录'),const SizedBox(height: 8),Text('文件位置: ${result.filePath}'),],),actions: [TextButton(onPressed: () => Navigator.pop(context),child: const Text('确定'),),FilledButton(onPressed: () {// 分享文件Share.shareFiles([result.filePath!]);Navigator.pop(context);},child: const Text('分享'),),],),);}void _showErrorDialog(String message) {showDialog(context: context,builder: (context) => AlertDialog(title: const Text('错误'),content: Text(message),actions: [TextButton(onPressed: () => Navigator.pop(context),child: const Text('确定'),),],),);}
}

性能优化策略

流式处理大文件

class StreamCsvProcessor {static Future<void> processLargeFile({required String filePath,required Function(List<String> row, int rowIndex) onRow,required Function(double progress) onProgress,}) async {final file = File(filePath);final fileLength = await file.length();int processedBytes = 0;final stream = file.openRead();final lines = stream.transform(utf8.decoder).transform(const LineSplitter());int rowIndex = 0;await for (final line in lines) {// 解析CSV行final row = _parseCsvLine(line);// 处理行数据await onRow(row, rowIndex);// 更新进度processedBytes += line.length + 1; // +1 for newlinefinal progress = processedBytes / fileLength;onProgress(progress.clamp(0.0, 1.0));rowIndex++;// 每处理100行让出一次控制权if (rowIndex % 100 == 0) {await Future.delayed(const Duration(milliseconds: 1));}}}static List<String> _parseCsvLine(String line) {// 简化的CSV行解析，实际使用应该用专业的CSV解析器final List<String> fields = [];bool inQuotes = false;StringBuffer currentField = StringBuffer();for (int i = 0; i < line.length; i++) {final char = line[i];if (char == '"') {if (inQuotes && i + 1 < line.length && line[i + 1] == '"') {// 转义的引号currentField.write('"');i++; // 跳过下一个引号} else {// 切换引号状态inQuotes = !inQuotes;}} else if (char == ',' && !inQuotes) {// 字段分隔符fields.add(currentField.toString());currentField.clear();} else {currentField.write(char);}}// 添加最后一个字段fields.add(currentField.toString());return fields;}
}

内存使用优化

class MemoryEfficientCsvImporter {static const int _batchSize = 100;static const int _maxMemoryRows = 1000;static Future<CsvImportResult> importWithMemoryLimit({required String csvContent,required Function(List<Transaction>) onBatch,required Function(double progress) onProgress,}) async {int totalRows = 0;int importedRows = 0;final List<ImportError> errors = [];// 分块处理CSV内容final chunks = _splitIntoChunks(csvContent, _maxMemoryRows);for (int chunkIndex = 0; chunkIndex < chunks.length; chunkIndex++) {final chunk = chunks[chunkIndex];final chunkResult = await _processChunk(chunk,totalRows,onBatch,);totalRows += chunkResult.totalRows;importedRows += chunkResult.importedRows;errors.addAll(chunkResult.errors);// 更新进度final progress = (chunkIndex + 1) / chunks.length;onProgress(progress);// 强制垃圾回收if (chunkIndex % 5 == 0) {await _forceGarbageCollection();}}return CsvImportResult(success: errors.isEmpty || importedRows > 0,totalRows: totalRows,importedRows: importedRows,skippedRows: totalRows - importedRows,errors: errors,);}static List<String> _splitIntoChunks(String content, int maxRowsPerChunk) {final lines = content.split('\n');final List<String> chunks = [];for (int i = 0; i < lines.length; i += maxRowsPerChunk) {final end = math.min(i + maxRowsPerChunk, lines.length);final chunkLines = lines.sublist(i, end);chunks.add(chunkLines.join('\n'));}return chunks;}static Future<ChunkImportResult> _processChunk(String chunk,int startRowIndex,Function(List<Transaction>) onBatch,) async {// 解析块数据final rows = const CsvToListConverter().convert(chunk);final List<Transaction> transactions = [];final List<ImportError> errors = [];for (int i = 0; i < rows.length; i++) {try {final transaction = _parseTransaction(rows[i]);if (transaction != null) {transactions.add(transaction);// 达到批次大小时处理if (transactions.length >= _batchSize) {await onBatch(List.from(transactions));transactions.clear();}}} catch (e) {errors.add(ImportError(row: startRowIndex + i + 1,message: e.toString(),));}}// 处理剩余交易if (transactions.isNotEmpty) {await onBatch(transactions);}return ChunkImportResult(totalRows: rows.length,importedRows: rows.length - errors.length,errors: errors,);}static Future<void> _forceGarbageCollection() async {// 触发垃圾回收的技巧final List<List<int>> dummy = [];for (int i = 0; i < 100; i++) {dummy.add(List.filled(1000, i));}dummy.clear();// 让出控制权，给垃圾回收器时间await Future.delayed(const Duration(milliseconds: 10));}
}

最佳实践总结

1. 文件处理原则

• 分批处理：大文件分批处理，避免内存溢出
• 流式处理：使用流式读取处理超大文件
• 错误恢复：提供重试和断点续传机制

2. 用户体验优化

• 进度反馈：实时显示处理进度
• 错误提示：清晰的错误信息和解决建议
• 智能映射：自动识别和映射常见字段

3. 数据验证

• 格式验证：严格验证数据格式和类型
• 业务验证：检查数据的业务逻辑正确性
• 重复检测：提供重复数据检测和处理选项

4. 性能考虑

• 内存管理：控制内存使用，及时释放资源
• 并发限制：限制并发操作数量
• 缓存策略：合理使用缓存提升性能

实际应用效果

在BeeCount项目中，CSV导入导出功能带来了显著价值：

1. 用户迁移便利：支持从其他记账应用快速迁移数据
2. 数据安全保障：提供本地数据备份和恢复能力
3. 分析能力增强：导出数据进行深度分析
4. 用户满意度提升：解决了数据互操作性问题

结语

CSV数据处理是移动应用的重要功能，需要在功能完整性、性能效率和用户体验之间找到平衡。通过合理的架构设计、性能优化和用户体验考虑，我们可以构建出既强大又易用的数据处理系统。

BeeCount的实践证明，优秀的CSV处理功能不仅能解决用户的实际需求，还能提升应用的专业性和竞争力，为用户提供真正的价值。

关于BeeCount项目

项目特色

• 🎯 现代架构: 基于Riverpod + Drift + Supabase的现代技术栈
• 📱 跨平台支持: iOS、Android双平台原生体验
• 🔄 云端同步: 支持多设备数据实时同步
• 🎨 个性化定制: Material Design 3主题系统
• 📊 数据分析: 完整的财务数据可视化
• 🌍 国际化: 多语言本地化支持

技术栈一览

• 框架: Flutter 3.6.1+ / Dart 3.6.1+
• 状态管理: Flutter Riverpod 2.5.1
• 数据库: Drift (SQLite) 2.20.2
• 云服务: Supabase 2.5.6
• 图表: FL Chart 0.68.0
• CI/CD: GitHub Actions

开源信息

BeeCount是一个完全开源的项目，欢迎开发者参与贡献：

• 项目主页: https://github.com/TNT-Likely/BeeCount
• 开发者主页: https://github.com/TNT-Likely
• 发布下载: GitHub Releases

参考资源

官方文档

• Dart CSV包文档 - Dart官方CSV处理库
• Flutter文件处理指南 - Flutter文件操作最佳实践

学习资源

• CSV格式规范 - RFC4180 CSV标准
• 大文件处理模式 - Dart流处理指南

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本文是BeeCount技术文章系列的第6篇，后续将深入探讨国际化、CI/CD等话题。如果你觉得这篇文章有帮助，欢迎关注项目并给个Star！