代码生成CSV文件

柔光的暖阳◎ 2021-12-16 02:59 395阅读 0赞

**简介:**

逗号分隔值（Comma-Separated Values，CSV，有时也称为字符分隔值，因为分隔字符也可以不是逗号），其文件以纯文本形式存储表格数据（数字和文本）。纯文本意味着该文件是一个字符序列，不含必须像二进制数字那样被解读的数据。CSV文件由任意数目的记录组成，记录间以某种换行符分隔；每条记录由字段组成，字段间的分隔符是其它字符或字符串，最常见的是逗号或制表符。通常，所有记录都有完全相同的字段序列。

**文件格式：**

sep=,                    //标记分隔符(这里是","号)

A1,A2,A3,A4,A5            //表头

1,2,3,4,5                //以下的每一行表示一条记录

11,22,33,44,55

111,222,333,444,555

…

**应用场景：**

CSV是一种通用的、相对简单的文件格式，被用户、商业和科学广泛应用。最广泛的应用是在程序之间转移表格数据，而这些程序本身是在不兼容的格式上进行操作的（往往是私有的和/或无规范的格式）。因为大量程序都支持某种CSV变体，至少是作为一种可选择的输入/输出格式。常用于数据的导入与导出。

**文件规则：**

1、开头是不留空，以行为单位

2、可含或不含列名，含列名则居文件第一行

3、一行数据不跨行，无空行

4、以半角逗号（即,）作分隔符，列为空也要表达其存在

5、列内容如存在半角引号（即"），替换成半角双引号（""）转义，即用半角引号（即""）将该字段值包含起来

6、文件读写时引号，逗号操作规则互逆

7、内码格式不限，可为 ASCII、Unicode 或者其他

8、不支持特殊字符

**C\# CVS文件导出类：**

publicclassCsvExport

///<summary>

/// To keep the ordered list of column names

///</summary>

List<string> \_fields = newList<string>();

///<summary>

/// The list of rows

///</summary>

List<Dictionary<string, object>> \_rows = newList<Dictionary<string, object>>();

///<summary>

/// The current row

///</summary>

Dictionary<string, object> \_currentRow \{ get \{ return \_rows\[\_rows.Count - 1\]; \} \}

///<summary>

/// The string used to separate columns in the output

///</summary>

privatereadonlystring \_columnSeparator;

///<summary>

/// Whether to include the preamble that declares which column separator is used in the output

///</summary>

privatereadonlybool \_includeColumnSeparatorDefinitionPreamble;

///<summary>

/// Initializes a new instance of the <see cref="Jitbit.Utils.CsvExport"/> class.

///</summary>

///<param name="columnSeparator">

/// The string used to separate columns in the output.

/// By default this is a comma so that the generated output is a CSV file.

///</param>

///<param name="includeColumnSeparatorDefinitionPreamble">

/// Whether to include the preamble that declares which column separator is used in the output.

/// By default this is <c>true</c> so that Excel can open the generated CSV

/// without asking the user to specify the delimiter used in the file.

///</param>

public CsvExport(string columnSeparator = ",", bool includeColumnSeparatorDefinitionPreamble = true)

\_columnSeparator = columnSeparator;

\_includeColumnSeparatorDefinitionPreamble = includeColumnSeparatorDefinitionPreamble;

///<summary>

/// Set a value on this column

///</summary>

publicobjectthis\[string field\]

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>

publicvoid AddRow()

\_rows.Add(newDictionary<string, object>());

///<summary>

/// Add a list of typed objects, maps object properties to CsvFields

///</summary>

publicvoid AddRows<T>(IEnumerable<T> list)

if (list.Any())

foreach (var obj in list)

AddRow();

var values = obj.GetType().GetProperties();

foreach (var value in values)

this\[value.Name\] = value.GetValue(obj, null);

///<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>

///<param name="columnSeparator">

/// The string used to separate columns in the output.

/// By default this is a comma so that the generated output is a CSV document.

///</param>

publicstaticstring MakeValueCsvFriendly(object value, string columnSeparator = ",")

if (value == null) return"";

if (value isINullable && ((INullable)value).IsNull) return"";

if (value isDateTime)

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().Trim();

if (output.Contains(columnSeparator) || output.Contains("\\"") || output.Contains("\\n") || output.Contains("\\r"))

output = '"' \+ output.Replace("\\"", "\\"\\"") + '"';

if (output.Length > 30000) //cropping value for stupid Excel

if (output.EndsWith("\\""))

output = output.Substring(0, 30000);

if (output.EndsWith("\\"") && !output.EndsWith("\\"\\"")) //rare situation when cropped line ends with a '"'

output += "\\""; //add another '"' to escape it

output += "\\"";

else

output = output.Substring(0, 30000);

return output;

///<summary>

/// Outputs all rows as a CSV, returning one string at a time

///</summary>

privateIEnumerable<string> ExportToLines()

if (\_includeColumnSeparatorDefinitionPreamble) yieldreturn"sep=" \+ \_columnSeparator;

// The header

yieldreturnstring.Join(\_columnSeparator, \_fields);

// The rows

foreach (Dictionary<string, object> row in \_rows)

foreach (string k in \_fields.Where(f => !row.ContainsKey(f)))

row\[k\] = null;

yieldreturnstring.Join(\_columnSeparator, \_fields.Select(field => MakeValueCsvFriendly(row\[field\], \_columnSeparator)));

///<summary>

/// Output all rows as a CSV returning a string

///</summary>

publicstring Export()

StringBuilder sb = newStringBuilder();

foreach (string line in ExportToLines())

sb.AppendLine(line);

return sb.ToString();

///<summary>

/// Exports to a file

///</summary>

publicvoid ExportToFile(string path)

File.WriteAllLines(path, ExportToLines(), Encoding.UTF8);

///<summary>

/// Exports to a file

///</summary>

publicvoid ExportToFile(string path, Encoding encoding)

File.WriteAllLines(path, ExportToLines(), encoding);

///<summary>

/// Exports as raw UTF8 bytes

///</summary>

publicbyte\[\] ExportToBytes()

var data = Encoding.UTF8.GetBytes(Export());

returnEncoding.UTF8.GetPreamble().Concat(data).ToArray();

//具体的调用：

CsvExport myExport = newCsvExport(); //创建对象

foreach (var data in list)

myExport.AddRow(); //添加行

foreach (var property in data)

myExport\[property.Name\] = property.Value; //设置列头和每一行对应的数据

myExport.ExportToFile(filePath, Encoding.Default); //按照编码导出csv文件

转载于:https://www.cnblogs.com/lanchong/p/7098734.html

代码生成CSV文件

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