linqtocsv文件有不太好的地方就是：无法设置标题的行数，默认首行就是标题，这不是很尴尬吗？ 并不是所有的csv文件严格写的首行是标题，下面全是数据，我接受的任务就是读取很多.csv报表数据，里面就有很多前几行是说明性内容，下面才是标题和数据。为了更好的解决这个问题，自己写吧...
本博客没有照搬linqtocsv全部源码，保留了主要功能，并对其优化，为我所用，哈哈...
下面是主要代码：
1-主文件CsvHelper：
这里在独自解析数据的时候，遇到了很多坑：
b-遇到了解析源文档数据时，未指定字符编码时，部分数据丢失导致csv文件个别行数据解析异常的问题，针对该问题，就是老老实实把读取文件时加了字符编码的参数进去，默认UTF-8。
using Microsoft.Extensions.Logging; PaymentAccountAPI.Helper; System; System.Collections.Generic; System.IO; System.Linq; System.Reflection; System.Text; namespace PaymentAccountAPI.CSV { public class CsvHelper { /// <summary> /// 日志 </summary> private ILogger _Logger { get; set; } public CsvHelper(ILogger<CsvHelper> logger) { this._Logger = logger; } public List<T> Read<T>(string filePath,CsvFileDescription fileDescription) where T : class,new() { List<T> tList = new List<T>(50 * 10000); T t = null; int currentRawIndex = 0; if (File.Exists(filePath)) { using (StreamReader streamReader = StreamReader(filePath,fileDescription.Encoding)) { Dictionary<int,FieldMapper> fieldMapperDic = FieldMapper.GetModelFieldMapper<T>().ToDictionary(m => m.CSVTitleIndex); string rawValue = ; string[] rawValueArray = ; PropertyInfo propertyInfo = string propertyValue = bool rawReadEnd = false; bool isExistSplitChart = do { rawValue = streamReader.ReadLine(); //标题行 if (currentRawIndex > fileDescription.TitleRawIndex) { if (!string.IsNullOrEmpty(rawValue)) { 替换字符串含有分隔符为{分隔符}，最后再替换回来 if (rawValue.Contains("\"")) { isExistSplitChart = true; int yhBeginIndex = ; int yhEndindex = string yhText = { yhBeginIndex = StringHelper.GetIndexOfStr(rawValue,",1)">1); yhEndindex = StringHelper.GetIndexOfStr(rawValue,1)">2); yhText = rawValue.Substring(yhBeginIndex,(yhEndindex - yhBeginIndex + )); string newYHText = yhText.Replace("").Replace(fileDescription.SeparatorChar.ToString(),1)">{分隔符}); rawValue = rawValue.Replace(yhText,newYHText); } while (rawValue.Contains()); } rawValueArray = rawValue.Split(fileDescription.SeparatorChar); t = T(); foreach (var fieldMapper in fieldMapperDic) { propertyInfo = fieldMapper.Value.PropertyInfo; propertyValue = rawValueArray[fieldMapper.Key - ]; .IsNullOrEmpty(propertyValue)) { try { if (isExistSplitChart && propertyValue.Contains()) { propertyValue = propertyValue.Replace(,fileDescription.SeparatorChar.ToString()); } TypeHelper.SetPropertyValue(t,propertyInfo.Name,propertyValue); } catch (Exception e) { this._Logger.LogWarning(e,$第{currentRawIndex + 1}行数据{propertyValue}转换属性{propertyInfo.Name}-{propertyInfo.PropertyType.Name}失败！); continue; } } } tList.Add(t); } else { rawReadEnd = ; } } currentRawIndex++; } while (rawReadEnd == ); } } return tList; } void WriteFile<T>(string path,List<T> tList,1)">() { .IsNullOrEmpty(path)) { string fileDirectoryPath = ; if (path.Contains(\\)) { fileDirectoryPath = path.Substring(0,path.LastIndexOf('')); } { fileDirectoryPath = path.Substring(/Directory.Exists(fileDirectoryPath)) { Directory.CreateDirectory(fileDirectoryPath); } int dataCount = tList.Count; Dictionary< m.CSVTitleIndex); int titleCount = fieldMapperDic.Keys.Max(); new [titleCount]; StringBuilder rawValueBuilder = StringBuilder(); ; T t = ; PropertyInfo propertyInfo = int tIndex = ; using (StreamWriter streamWriter = new StreamWriter(path,fileDescription.Encoding)) { { { rawValue = ""; #if DEBUG if (currentRawIndex % 10000 == ) { this._Logger.Log@R_619_4045@ion($已写入文件：{path}，数据量：{currentRawIndex}); } #endif if (currentRawIndex >= fileDescription.TitleRawIndex) { 清空数组数据 for (int i = 0; i < titleCount; i++) { rawValueArray[i] = ; } fileDescription.TitleRawIndex) { t = tList[tIndex]; tIndex++; } var fieldMapperItem fieldMapperDic) { 写入标题行 if (currentRawIndex == fileDescription.TitleRawIndex) { rawValueArray[fieldMapperItem.Key - 1] = fieldMapperItem.Value.CSVTitle; } 真正的数据从标题行下一行开始写 { propertyInfo = fieldMapperItem.Value.PropertyInfo; object propertyValue = propertyInfo.GetValue(t); string formatValue = ; if (propertyValue != ) { if (propertyInfo.PropertyType is IFormattable && !.IsNullOrEmpty(fieldMapperItem.Value.OutputFormat)) { formatValue = ((IFormattable)propertyValue).ToString(fieldMapperItem.Value.OutputFormat,1)">); } { formatValue = propertyValue.ToString(); } 如果属性值含有分隔符，则使用双引号包裹 (formatValue.Contains(fileDescription.SeparatorChar.ToString())) { formatValue = $\"{formatValue}\"; } rawValueArray[fieldMapperItem.Key - formatValue; } } } rawValue = .Join(fileDescription.SeparatorChar,rawValueArray); } rawValueBuilder.Append(rawValue + \r\n); } (Exception e) { (异常)Excel第{currentRawIndex+1}行，数据列表第{tIndex + 1}个数据写入失败！rawValue：{rawValue}); throw; } currentRawIndex++while (tIndex < dataCount); streamWriter.Write(rawValueBuilder.ToString()); streamWriter.Close(); streamWriter.dispose(); } } } } }
2-CSV映射类特性：
System; PaymentAccountAPI.CSV { <summary> Csv文件类特性标记 </summary> [System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property,AllowMultiple = )] CsvColumnAttribute : System.Attribute { internal const int defaultTitleIndex = Int32.MaxValue; 标题 string Title { ; } 标题位置（从0开始） int TitleIndex { 字符输出格式（数字和日期类型需要） string OutputFormat { public CsvColumnAttribute() { Title = ; TitleIndex = defaultTitleIndex; OutputFormat = ; } public CsvColumnAttribute(string title,1)">int titleIndex,1)"> outputFormat) { Title = title; TitleIndex = titleIndex; OutputFormat = outputFormat; } } }
3-CSV文件描述信息类：
CsvFileDescription { public CsvFileDescription() : this() { } public CsvFileDescription(int titleRawIndex) : char separatorChar,1)">int titleRawIndex,Encoding encoding) { this.SeparatorChar = separatorChar; this.TitleRawIndex = titleRawIndex; this.Encoding = encoding; } CSV文件字符编码 public Encoding Encoding { ; } 分隔符（默认为（,）,也可以是其他分隔符如(\t)） char SeparatorChar { 标题所在行位置（默认为0，没有标题填-1） int TitleRawIndex { ; } } }
4-映射类获取关系帮助类：
System.Reflection; 字段映射类 </summary> FieldMapper { 属性信息 public PropertyInfo PropertyInfo { string CSVTitle { 标题下标位置 int CSVTitleIndex { static List<FieldMapper> GetModelFieldMapper<T>() { List<FieldMapper> fieldMapperList = new List<FieldMapper>(100); List<PropertyInfo> tPropertyInfoList = typeof(T).GetProperties().ToList(); CsvColumnAttribute csvColumnAttribute = var tPropertyInfo tPropertyInfoList) { csvColumnAttribute = (CsvColumnAttribute)tPropertyInfo.GetCustomAttribute((CsvColumnAttribute)); if (csvColumnAttribute != ) { fieldMapperList.Add( FieldMapper { PropertyInfo = tPropertyInfo,CSVTitle = csvColumnAttribute.Title,CSVTitleIndex = csvColumnAttribute.TitleIndex,OutputFormat = csvColumnAttribute.OutputFormat }); } } fieldMapperList; } } }
5-其他扩展类：
PaymentAccountAPI.Helper { StringHelper { 获取字符串中第strPosition个位置的str的下标 </summary> <param name="text"></param> <param name="str"></param> <param name="strPosition"></param> <returns></returns> static int GetIndexOfStr(string text,1)">string str,1)"> strPosition) { int strIndex = -int currentPosition = string.IsNullOrEmpty(text) && !string.IsNullOrEmpty(str) && strPosition >= ) { { currentPosition++if (strIndex == -) { strIndex = text.IndexOf(str); } { strIndex = text.IndexOf(str,strIndex + ); } } while (currentPosition < strPosition); } strIndex; } } }
最后就是将CsvHelper注入到单例中，就可以使用了...
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