C#_.net core 3.0自定义读取.csv文件数据_解决首行不是标题的问题_Linqtocsv改进
作者：互联网
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：
a-遇到数据含有分隔符的问题的解决办法，代码已经包含了
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;
using PaymentAccountAPI.Helper;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using 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 = 1;
if (File.Exists(filePath))
{
using (StreamReader streamReader = new StreamReader(filePath, fileDescription.Encoding))
{
Dictionary<int, FieldMapper> fieldMapperDic = FieldMapper.GetModelFieldMapper<T>().ToDictionary(m => m.CSVTitleIndex);
string rawValue = null;
string[] rawValueArray = null;
PropertyInfo propertyInfo = null;
string propertyValue = null;
bool rawReadEnd = false;
bool isExistSplitChart = false;
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 = 0;
int yhEndIndex = 0;
string yhText = null;
do
{
yhBeginIndex = StringHelper.GetIndexOfStr(rawValue, "\"", 1);
yhEndIndex = StringHelper.GetIndexOfStr(rawValue, "\"", 2);
yhText = rawValue.Substring(yhBeginIndex, (yhEndIndex - yhBeginIndex + 1));
string newYHText = yhText.Replace("\"", "").Replace(fileDescription.SeparatorChar.ToString(), "{分隔符}");
rawValue = rawValue.Replace(yhText, newYHText);
} while (rawValue.Contains("\""));
}
rawValueArray = rawValue.Split(fileDescription.SeparatorChar);
t = new T();
foreach (var fieldMapper in fieldMapperDic)
{
propertyInfo = fieldMapper.Value.PropertyInfo;
propertyValue = rawValueArray[fieldMapper.Key - 1];
if (!string.IsNullOrEmpty(propertyValue))
{
try
{
if (isExistSplitChart && propertyValue.Contains("{分隔符}"))
{
propertyValue = propertyValue.Replace("{分隔符}", fileDescription.SeparatorChar.ToString());
}
TypeHelper.SetPropertyValue(t, propertyInfo.Name, propertyValue);
}
catch (Exception e)
{
this._Logger.LogWarning(e, $"第{currentRawIndex + 1}行数据{propertyValue}转换属性{propertyInfo.Name}-{propertyInfo.PropertyType.Name}失败！");
continue;
}
}
}
tList.Add(t);
}
else
{
rawReadEnd = true;
}
}
currentRawIndex++;
} while (rawReadEnd == false);
}
}
return tList;
}
public void WriteFile<T>(string path, List<T> tList, CsvFileDescription fileDescription) where T : class, new()
{
if (!string.IsNullOrEmpty(path))
{
string fileDirectoryPath = null;
if (path.Contains("\\"))
{
fileDirectoryPath = path.Substring(0, path.LastIndexOf('\\'));
}
else
{
fileDirectoryPath = path.Substring(0, path.LastIndexOf('/'));
}
if (!Directory.Exists(fileDirectoryPath))
{
Directory.CreateDirectory(fileDirectoryPath);
}
int dataCount = tList.Count;
Dictionary<int, FieldMapper> fieldMapperDic = FieldMapper.GetModelFieldMapper<T>().ToDictionary(m => m.CSVTitleIndex);
int titleCount = fieldMapperDic.Keys.Max();
string[] rawValueArray = new string[titleCount];
StringBuilder rawValueBuilder = new StringBuilder();
string rawValue = null;
T t = null;
PropertyInfo propertyInfo = null;
int currentRawIndex = 1;
int tIndex = 0;
using (StreamWriter streamWriter = new StreamWriter(path, false, fileDescription.Encoding))
{
do
{
try
{
rawValue = "";
#if DEBUG
if (currentRawIndex % 10000 == 0)
{
this._Logger.LogInformation($"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] = "";
}
if (currentRawIndex > fileDescription.TitleRawIndex)
{
t = tList[tIndex];
tIndex++;
}
foreach (var fieldMapperItem in 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
else
{
propertyInfo = fieldMapperItem.Value.PropertyInfo;
object propertyValue = propertyInfo.GetValue(t);
string formatValue = null;
if (propertyValue != null)
{
if (propertyInfo.PropertyType is IFormattable && !string.IsNullOrEmpty(fieldMapperItem.Value.OutputFormat))
{
formatValue = ((IFormattable)propertyValue).ToString(fieldMapperItem.Value.OutputFormat, null);
}
else
{
formatValue = propertyValue.ToString();
}
//如果属性值含有分隔符，则使用双引号包裹
if (formatValue.Contains(fileDescription.SeparatorChar.ToString()))
{
formatValue = $"\"{formatValue}\"";
}
rawValueArray[fieldMapperItem.Key - 1] = formatValue;
}
}
}
rawValue = string.Join(fileDescription.SeparatorChar, rawValueArray);
}
rawValueBuilder.Append(rawValue + "\r\n");
}
catch (Exception e)
{
this._Logger.LogWarning(e, $"(异常)Excel第{currentRawIndex}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：
using System;
namespace PaymentAccountAPI.CSV
{
/// <summary>
/// Csv文件类特性标记
/// </summary>
[System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property, AllowMultiple = false)]
public class CsvColumnAttribute : System.Attribute
{
internal const int defaultTitleIndex = Int32.MaxValue;
/// <summary>
/// 标题
/// </summary>
public string Title { get; set; }
/// <summary>
/// 标题位置（从1开始）
/// </summary>
public int TitleIndex { get; set; }
/// <summary>
/// 字符输出格式（数字和日期类型需要）
/// </summary>
public string OutputFormat { get; set; }
public CsvColumnAttribute()
{
Title = "";
TitleIndex = defaultTitleIndex;
OutputFormat = "";
}
public CsvColumnAttribute(string title, int titleIndex, string outputFormat)
{
Title = title;
TitleIndex = titleIndex;
OutputFormat = outputFormat;
}
}
}
3-CSV文件描述信息类：
using System.Text;
namespace PaymentAccountAPI.CSV
{
public class CsvFileDescription
{
public CsvFileDescription() : this(1)
{
}
public CsvFileDescription(int titleRawIndex) : this(',', titleRawIndex, Encoding.UTF8)
{
}
public CsvFileDescription(char separatorChar, int titleRawIndex, Encoding encoding)
{
this.SeparatorChar = separatorChar;
this.TitleRawIndex = titleRawIndex;
this.Encoding = encoding;
}
/// <summary>
/// CSV文件字符编码
/// </summary>
public Encoding Encoding { get; set; }
/// <summary>
/// 分隔符（默认为（,）,也可以是其他分隔符如(\t)）
/// </summary>
public char SeparatorChar { get; set; }
/// <summary>
/// 标题所在行位置（默认为1，没有标题填0）
/// </summary>
public int TitleRawIndex { get; set; }
}
}
4-映射类获取关系帮助类：
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
namespace PaymentAccountAPI.CSV
{
/// <summary>
/// 字段映射类
/// </summary>
public class FieldMapper
{
/// <summary>
/// 属性信息
/// </summary>
public PropertyInfo PropertyInfo { get; set; }
/// <summary>
/// 标题
/// </summary>
public string CSVTitle { get; set; }
/// <summary>
/// 标题下标位置
/// </summary>
public int CSVTitleIndex { get; set; }
/// <summary>
/// 字符输出格式（数字和日期类型需要）
/// </summary>
public string OutputFormat { get; set; }
public static List<FieldMapper> GetModelFieldMapper<T>()
{
List<FieldMapper> fieldMapperList = new List<FieldMapper>(100);
List<PropertyInfo> tPropertyInfoList = typeof(T).GetProperties().ToList();
CsvColumnAttribute csvColumnAttribute = null;
foreach (var tPropertyInfo in tPropertyInfoList)
{
csvColumnAttribute = (CsvColumnAttribute)tPropertyInfo.GetCustomAttribute(typeof(CsvColumnAttribute));
if (csvColumnAttribute != null)
{
fieldMapperList.Add(new FieldMapper
{
PropertyInfo = tPropertyInfo,
CSVTitle = csvColumnAttribute.Title,
CSVTitleIndex = csvColumnAttribute.TitleIndex,
OutputFormat = csvColumnAttribute.OutputFormat
});
}
}
return fieldMapperList;
}
}
}
5-其他扩展类：
namespace PaymentAccountAPI.Helper
{
public class StringHelper
{
/// <summary>
/// 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>
public static int GetIndexOfStr(string text, string str, int strPosition)
{
int strIndex = -1;
int currentPosition = 0;
if (!string.IsNullOrEmpty(text) && !string.IsNullOrEmpty(str) && strPosition >= 1)
{
do
{
currentPosition++;
if (strIndex == -1)
{
strIndex = text.IndexOf(str);
}
else
{
strIndex = text.IndexOf(str, strIndex + 1);
}
} while (currentPosition < strPosition);
}
return strIndex;
}
}
}
最后就是将CsvHelper注入到单例中，就可以使用了...
标签：core,string,自定义,int,System,Linqtocsv,using,public,rawValue 来源： https://www.cnblogs.com/lxhbky/p/12219080.html