我正在寻找一个用于创建CSV Excel文件的课程。
预期功能：
你知道哪个班级能够做到这一点吗？
答案 0 :(得分：92)
我根据自己的需要使用反射编写了略有不同的版本。我不得不将对象列表导出到csv。如果有人想将它用于将来。
public class CsvExport<T> where T: class
{
public List<T> Objects;
public CsvExport(List<T> objects)
{
Objects = objects;
}
public string Export()
{
return Export(true);
}
public string Export(bool includeHeaderLine)
{
StringBuilder sb = new StringBuilder();
//Get properties using reflection.
IList<PropertyInfo> propertyInfos = typeof(T).GetProperties();
if (includeHeaderLine)
{
//add header line.
foreach (PropertyInfo propertyInfo in propertyInfos)
{
sb.Append(propertyInfo.Name).Append(",");
}
sb.Remove(sb.Length - 1, 1).AppendLine();
}
//add value for each property.
foreach (T obj in Objects)
{
foreach (PropertyInfo propertyInfo in propertyInfos)
{
sb.Append(MakeValueCsvFriendly(propertyInfo.GetValue(obj, null))).Append(",");
}
sb.Remove(sb.Length - 1, 1).AppendLine();
}
return sb.ToString();
}
//export to a file.
public void ExportToFile(string path)
{
File.WriteAllText(path, Export());
}
//export as binary data.
public byte[] ExportToBytes()
{
return Encoding.UTF8.GetBytes(Export());
}
//get the csv value for field.
private string MakeValueCsvFriendly(object value)
{
if (value == null) return "";
if (value is Nullable && ((INullable)value).IsNull) return "";
if (value is DateTime)
{
if (((DateTime)value).TimeOfDay.TotalSeconds == 0)
return ((DateTime)value).ToString("yyyy-MM-dd");
return ((DateTime)value).ToString("yyyy-MM-dd HH:mm:ss");
}
string output = value.ToString();
if (output.Contains(",") || output.Contains("\""))
output = '"' + output.Replace("\"", "\"\"") + '"';
return output;
}
}
使用示例:(根据评论更新）
CsvExport<BusinessObject> csv= new CsvExport<BusinessObject>(GetBusinessObjectList());
Response.Write(csv.Export());
答案 1 :(得分：19)
请原谅我
但我认为公共开源存储库是一种更好的方式来共享代码，做出贡献，更正，以及“我修复了这个，我修复了”
所以我从主题 - 首发代码和所有添加内容中创建了一个简单的git-repository：
https://github.com/jitbit/CsvExport
我自己也添加了一些有用的修复程序。每个人都可以添加建议，分发它以贡献等等。把你的叉子发给我，这样我就把它们合并回到回购中。
PS。我发布了Chris的所有版权声明。 @Chris，如果你反对这个想法 - 让我知道，我会杀了它。
答案 2 :(得分：11)
读取和写入CSV文件的另一个好方法是filehelpers（开源）。
答案 3 :(得分：6)
如何使用string.Join代替所有foreach循环？
答案 4 :(得分：6)
如果有人想我将其转换为IEnumerable上的扩展方法：
public static class ListExtensions
{
public static string ExportAsCSV<T>(this IEnumerable<T> listToExport, bool includeHeaderLine, string delimeter)
{
StringBuilder sb = new StringBuilder();
IList<PropertyInfo> propertyInfos = typeof(T).GetProperties();
if (includeHeaderLine)
{
foreach (PropertyInfo propertyInfo in propertyInfos)
{
sb.Append(propertyInfo.Name).Append(",");
}
sb.Remove(sb.Length - 1, 1).AppendLine();
}
foreach (T obj in listToExport)
{
T localObject = obj;
var line = String.Join(delimeter, propertyInfos.Select(x => SanitizeValuesForCSV(x.GetValue(localObject, null), delimeter)));
sb.AppendLine(line);
}
return sb.ToString();
}
private static string SanitizeValuesForCSV(object value, string delimeter)
{
string output;
if (value == null) return "";
if (value is DateTime)
{
output = ((DateTime)value).ToLongDateString();
}
else
{
output = value.ToString();
}
if (output.Contains(delimeter) || output.Contains("\""))
output = '"' + output.Replace("\"", "\"\"") + '"';
output = output.Replace("\n", " ");
output = output.Replace("\r", "");
return output;
}
}
答案 5 :(得分：5)
这堂课的伟大工作。简单易用。我修改了类以在导出的第一行中包含标题;想我会分享：
使用：
CsvExport myExport = new CsvExport();
myExport.addTitle = String.Format("Name: {0},{1}", lastName, firstName));
类：
public class CsvExport
{
List<string> fields = new List<string>();
public string addTitle { get; set; } // string for the first row of the export
List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
Dictionary<string, object> currentRow
{
get
{
return rows[rows.Count - 1];
}
}
public object this[string field]
{
set
{
if (!fields.Contains(field)) fields.Add(field);
currentRow[field] = value;
}
}
public void AddRow()
{
rows.Add(new Dictionary<string, object>());
}
string MakeValueCsvFriendly(object value)
{
if (value == null) return "";
if (value is Nullable && ((INullable)value).IsNull) return "";
if (value is DateTime)
{
if (((DateTime)value).TimeOfDay.TotalSeconds == 0)
return ((DateTime)value).ToString("yyyy-MM-dd");
return ((DateTime)value).ToString("yyyy-MM-dd HH:mm:ss");
}
string output = value.ToString();
if (output.Contains(",") || output.Contains("\""))
output = '"' + output.Replace("\"", "\"\"") + '"';
return output;
}
public string Export()
{
StringBuilder sb = new StringBuilder();
// if there is a title
if (!string.IsNullOrEmpty(addTitle))
{
// escape chars that would otherwise break the row / export
char[] csvTokens = new[] { '\"', ',', '\n', '\r' };
if (addTitle.IndexOfAny(csvTokens) >= 0)
{
addTitle = "\"" + addTitle.Replace("\"", "\"\"") + "\"";
}
sb.Append(addTitle).Append(",");
sb.AppendLine();
}
// The header
foreach (string field in fields)
sb.Append(field).Append(",");
sb.AppendLine();
// The rows
foreach (Dictionary<string, object> row in rows)
{
foreach (string field in fields)
sb.Append(MakeValueCsvFriendly(row[field])).Append(",");
sb.AppendLine();
}
return sb.ToString();
}
public void ExportToFile(string path)
{
File.WriteAllText(path, Export());
}
public byte[] ExportToBytes()
{
return Encoding.UTF8.GetBytes(Export());
}
}
答案 6 :(得分：4)
有一个CSV的开源库，您可以使用nuget获取：http://joshclose.github.io/CsvHelper/
答案 7 :(得分：3)
我添加了ExportToStream，因此csv不必先保存到硬盘驱动器。
public Stream ExportToStream()
{
MemoryStream stream = new MemoryStream();
StreamWriter writer = new StreamWriter(stream);
writer.Write(Export(true));
writer.Flush();
stream.Position = 0;
return stream;
}
答案 8 :(得分：3)
我添加了
public void ExportToFile(string path, DataTable tabela)
{
DataColumnCollection colunas = tabela.Columns;
foreach (DataRow linha in tabela.Rows)
{
this.AddRow();
foreach (DataColumn coluna in colunas)
{
this[coluna.ColumnName] = linha[coluna];
}
}
this.ExportToFile(path);
}
以前的代码不适用于旧的.NET版本。对于3.5版本的框架，请使用此其他版本：
public void ExportToFile(string path)
{
bool abort = false;
bool exists = false;
do
{
exists = File.Exists(path);
if (!exists)
{
if( !Convert.ToBoolean( File.CreateText(path) ) )
abort = true;
}
} while (!exists || abort);
if (!abort)
{
//File.OpenWrite(path);
using (StreamWriter w = File.AppendText(path))
{
w.WriteLine("hello");
}
}
//File.WriteAllText(path, Export());
}
答案 9 :(得分：2)
非常感谢！ 我将课程修改为：
MakeValueCsvFriendly 代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Data.SqlTypes;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
public class CsvExport
{
public char delim = ';';
/// <summary>
/// To keep the ordered list of column names
/// </summary>
List<string> fields = new List<string>();
/// <summary>
/// The list of rows
/// </summary>
List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
/// <summary>
/// The current row
/// </summary>
Dictionary<string, object> currentRow { get { return rows[rows.Count - 1]; } }
/// <summary>
/// Set a value on this column
/// </summary>
public object this[string field]
{
set
{
// Keep track of the field names, because the dictionary loses the ordering
if (!fields.Contains(field)) fields.Add(field);
currentRow[field] = value;
}
}
/// <summary>
/// Call this before setting any fields on a row
/// </summary>
public void AddRow()
{
rows.Add(new Dictionary<string, object>());
}
/// <summary>
/// Converts a value to how it should output in a csv file
/// If it has a comma, it needs surrounding with double quotes
/// Eg Sydney, Australia -> "Sydney, Australia"
/// Also if it contains any double quotes ("), then they need to be replaced with quad quotes[sic] ("")
/// Eg "Dangerous Dan" McGrew -> """Dangerous Dan"" McGrew"
/// </summary>
string MakeValueCsvFriendly(object value)
{
if (value == null) return "";
if (value is INullable && ((INullable)value).IsNull) return "";
if (value is DateTime)
{
if (((DateTime)value).TimeOfDay.TotalSeconds == 0)
return ((DateTime)value).ToString("yyyy-MM-dd");
return ((DateTime)value).ToString("yyyy-MM-dd HH:mm:ss");
}
string output = value.ToString();
if (output.Contains(delim) || output.Contains("\""))
output = '"' + output.Replace("\"", "\"\"") + '"';
if (Regex.IsMatch(output, @"(?:\r\n|\n|\r)"))
output = string.Join(" ", Regex.Split(output, @"(?:\r\n|\n|\r)"));
return output;
}
/// <summary>
/// Output all rows as a CSV returning a string
/// </summary>
public string Export()
{
StringBuilder sb = new StringBuilder();
// The header
foreach (string field in fields)
sb.Append(field).Append(delim);
sb.AppendLine();
// The rows
foreach (Dictionary<string, object> row in rows)
{
foreach (string field in fields)
sb.Append(MakeValueCsvFriendly(row[field])).Append(delim);
sb.AppendLine();
}
return sb.ToString();
}
/// <summary>
/// Exports to a file
/// </summary>
public void ExportToFile(string path)
{
File.WriteAllText(path, Export());
}
/// <summary>
/// Exports as raw UTF8 bytes
/// </summary>
public byte[] ExportToBytes()
{
return Encoding.UTF8.GetBytes(Export());
}
}
答案 10 :(得分：1)
答案 11 :(得分：1)
原始类有问题，即如果要添加新列，您将在Export方法上收到KeyNotFoundException。例如：
static void Main(string[] args)
{
var export = new CsvExport();
export.AddRow();
export["Region"] = "New York, USA";
export["Sales"] = 100000;
export["Date Opened"] = new DateTime(2003, 12, 31);
export.AddRow();
export["Region"] = "Sydney \"in\" Australia";
export["Sales"] = 50000;
export["Date Opened"] = new DateTime(2005, 1, 1, 9, 30, 0);
export["Balance"] = 3.45f; //Exception is throwed for this new column
export.ExportToFile("Somefile.csv");
}
为了解决这个问题，并使用@KeyboardCowboy使用反射的想法，我修改了代码以允许添加不具有相同列的行。您可以使用匿名类的实例。例如：
static void Main(string[] args)
{
var export = new CsvExporter();
export.AddRow(new {A = 12, B = "Empty"});
export.AddRow(new {A = 34.5f, D = false});
export.ExportToFile("File.csv");
}
您可以在此处下载源代码CsvExporter。随意使用和修改。
现在，如果你要编写的所有行都属于同一个类，我创建了通用类CsvWriter.cs，它具有更好的RAM性能，是编写大文件的理想选择。它可以让你添加格式化程序您想要的数据类型。使用示例：
class Program
{
static void Main(string[] args)
{
var writer = new CsvWriter<Person>("Persons.csv");
writer.AddFormatter<DateTime>(d => d.ToString("MM/dd/yyyy"));
writer.WriteHeaders();
writer.WriteRows(GetPersons());
writer.Flush();
writer.Close();
}
private static IEnumerable<Person> GetPersons()
{
yield return new Person
{
FirstName = "Jhon",
LastName = "Doe",
Sex = 'M'
};
yield return new Person
{
FirstName = "Jhane",
LastName = "Doe",
Sex = 'F',
BirthDate = DateTime.Now
};
}
}
class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
public char Sex { get; set; }
public DateTime BirthDate { get; set; }
}
答案 12 :(得分：0)
您只需要1个功能即可完成此操作。 您只需要在解决方案资源管理器中创建一个文件夹并将csv文件存储在那里，然后将该文件导出给用户。
在我的情况下，我有一个文件夹下载。首先，我将所有内容导出到该目录，然后将其导出给用户。对于response.end处理，我使用了ThreadAbortException。因此，在我的解决方案中，它是100％真实且有效的功能。
protected void lnkExport_OnClick(object sender, EventArgs e)
{
string filename = strFileName = "Export.csv";
DataTable dt = obj.GetData();
// call the content and load it into the datatable
strFileName = Server.MapPath("Downloads") + "\\" + strFileName;
// creating a file in the downloads folder in your solution explorer
TextWriter tw = new StreamWriter(strFileName);
// using the built in class textwriter for writing your content in the exporting file
string strData = "Username,Password,City";
// above line is the header for your exported file. So add headings for your coloumns in excel(.csv) file and seperate them with ","
strData += Environment.NewLine;
// setting the environment to the new line
foreach (DataRow dr in dt.Rows)
{
strData += dr["Username"].ToString() + "," + dr["Password"].ToString() + "," + dr["City"].ToString();
strData += Environment.NewLine;
}
// everytime when loop execute, it adds a line into the file
tw.Write(strData);
// writing the contents in file
tw.Close();
// closing the file
Response.Redirect("Downloads/" + filename);
// exporting the file to the user as a popup to save as....
}