在C#中创建.csv文件

Question

好吧我想在C#中创建一个.csv文件.我一直在四处寻找并注意到很多人正在使用system.IO.memorystream和system.io.streamwriter.

问题是:我有一个Web应用程序.我想让用户能够导出到excel.问题是,Excel无法安装在服务器上(不要问).我希望能够为报告编写.csv工作表导出.现在,报告标题和数据对于所有报告都是不同的(循环将解决此问题).任何人都有一个例子或更好的资源让我通过？

Answer 1

这是我通常采用的方法.可能不是最有效的.

        /// <summary>
    /// Generates the contents of the log file.
    /// </summary>
    /// <returns>The contents of the log file.</returns>
    internal string GenerateLogFile()
    {
        StringBuilder csvExport = new StringBuilder();
        csvExport.AppendLine(Resources.CSVHeader);

        foreach (DataRow row in this.logEntries.Rows)
        {
            csvExport.AppendLine(
                string.Format(
                "\"{0}\",\"{1}\",\"{2}\",\"{3}\",\"{4}\",\"{5}\",\"{6}\",\"{7}\",\"{8}\", \"{9}\"",
                row[ColumnNames.LogTime], row[ColumnNames.Field1], row[ColumnNames.Field2], row[ColumnNames.Field3], row[ColumnNames.Field4], row[ColumnNames.Field5], row[ColumnNames.Field6], row[ColumnNames.Field7], row[ColumnNames.Field8], row[ColumnNames.Field9]));
        }

        return csvExport.ToString();
    }

    /// <summary>
    /// Adds the CSV file to the response.
    /// </summary>
    /// <param name="csvExportContents">The contents of the CSV file.</param>
    internal void DisplayLogFile(string csvExportContents)
    {
        byte[] data = new ASCIIEncoding().GetBytes(csvExportContents);

        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.ContentType = "APPLICATION/OCTET-STREAM";
        HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment; filename=Export.csv");
        HttpContext.Current.Response.OutputStream.Write(data, 0, data.Length);
        HttpContext.Current.Response.End();
    }

Answer 2

private void WriteItem<T>(StreamWriter sr, T item)
{
    string itemString = item.ToString();
    if(itemString.IndexOfAny(new char[] { '"', ',', '\n', '\r' }) != -1)//skip test and always escape for different speed/filesize optimisation
    {
        sr.Write('"');
        sr.Write(itemString.Replace("\"", "\"\""));
        sr.Write('"');
    }
    else
        sr.Write(itemString);
}
private void WriteLine<T>(StreamWriter sr, IEnumerable<T> line)
{
    bool first = true;
    foreach(T item in line)
    {
        if(!first)
            sr.Write(',');
        first = false;
        WriteItem(sr, item);
    }
}
private void WriteCSV<T>(StreamWriter sr, IEnumerable<IEnumerable<T>> allLines)
{
    bool first = true;
    foreach(IEnumerable<T> line in allLines)
    {
        if(!first)
            sr.Write('\n');
        first = false;
        WriteLine(sr, line);
    }
}
private void WriteCSV<T>(HttpResponse response, IEnumerable<IEnumerable<T>> allLines)
{
    response.ContentType = "text/csv";
    WriteCSV(response.Output, allLines);
}

还可以使用推荐的文件名发送内容处置标头.

编辑:最近,如果需要在枚举中的项之间间隔一个动作(如上面的逗号和换行符),我宁愿保留一个继续被检查的布尔值,我直接处理枚举器,然后处理与其余元素分开的第一个元素.我开始将这作为效率推动的微观选择,但已经发展到只是发现它更好地表达了第一项不同的代码路径.因此,我现在将上述内容写成:

private void WriteLine<T>(StreamWriter sr, IEnumerable<T> line)
{
  using(var en = line.GetEnumerator())
  if(en.MoveNext())
  {
    WriteItem(sr, en.Current);
    while(en.MoveNext())
    {
      sr.Write(',');
      WriteItem(sr, en.Current);
    }
}
private void WriteCSV<T>(StreamWriter sr, IEnumerable<IEnumerable<T>> allLines)
{
    using(var en = allLines.GetEnumerator())
    if(en.MoveNext())
    {
      WriteLine(sr, en.Current);
      while(en.MoveNext())
      {
        sr.Write('\n');
        WriteLine(sr, en.Current);
      }
    }
}