Question

我有一个要求，我需要从给定的URL下载csv文件，然后将数据从文件导出到数据库。

有没有办法将文件直接下载并转换为datatable，而不是将其保存到硬盘，然后将其读取到数据表。

希望我的问题有道理。

提前致谢

Answer 1

string FileName = ...
OleDbConnection conn = new OleDbConnection
       ("Provider=Microsoft.Jet.OleDb.4.0; Data Source = " + 
         Path.GetDirectoryName(FileName) + 
         "; Extended Properties = \"Text;HDR=YES;FMT=Delimited\"");

conn.Open();

OleDbDataAdapter adapter = new OleDbDataAdapter
       ("SELECT * FROM " + Path.GetFileName(FileName), conn);

DataSet ds = new DataSet("Temp");
adapter.Fill(ds);

conn.Close();

Answer 2

您可以使用StreamReader类下载csv而无需在本地保存：

public string DownloadCSV(string url)
{
    HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
    HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest .GetResponse();

    StreamReader streamReader = new StreamReader(httpWebResponse .GetResponseStream());
    string results = streamReader.ReadToEnd();
    streamReader .Close();

    return results;
}

Answer 3

我在下面写了五种方法。

它们的设计考虑了可选的引号（例如＆＃34;符号），并且在不使用其他库的情况下尽可能多样化：

    public static DataTable GetDataTabletFromCSVFile(string filePath, bool isHeadings)
    {
        DataTable MethodResult = null;
        try
        {
            using (TextFieldParser TextFieldParser = new TextFieldParser(filePath))
            {
                if (isHeadings)
                {
                    MethodResult = GetDataTableFromTextFieldParser(TextFieldParser);

                }
                else
                {
                    MethodResult = GetDataTableFromTextFieldParserNoHeadings(TextFieldParser);

                }

            }

        }
        catch (Exception ex)
        {
            ex.HandleException();
        }
        return MethodResult;
    }

    public static DataTable GetDataTableFromCsvString(string csvBody, bool isHeadings)
    {
        DataTable MethodResult = null;
        try
        {
            MemoryStream MemoryStream = new MemoryStream();


            StreamWriter StreamWriter = new StreamWriter(MemoryStream);

            StreamWriter.Write(csvBody);

            StreamWriter.Flush();


            MemoryStream.Position = 0;


            using (TextFieldParser TextFieldParser = new TextFieldParser(MemoryStream))
            {
                if (isHeadings)
                {
                    MethodResult = GetDataTableFromTextFieldParser(TextFieldParser);

                }
                else
                {
                    MethodResult = GetDataTableFromTextFieldParserNoHeadings(TextFieldParser);

                }

            }

        }
        catch (Exception ex)
        {
            ex.HandleException();
        }
        return MethodResult;
    }

    public static DataTable GetDataTableFromRemoteCsv(string url, bool isHeadings)
    {
        DataTable MethodResult = null;
        try
        {
            HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
            HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();

            StreamReader StreamReader = new StreamReader(httpWebResponse.GetResponseStream());

            using (TextFieldParser TextFieldParser = new TextFieldParser(StreamReader))
            {
                if (isHeadings)
                {
                    MethodResult = GetDataTableFromTextFieldParser(TextFieldParser);

                }
                else
                {
                    MethodResult = GetDataTableFromTextFieldParserNoHeadings(TextFieldParser);

                }

            }

        }
        catch (Exception ex)
        {
            ex.HandleException();
        }
        return MethodResult;
    }


    private static DataTable GetDataTableFromTextFieldParser(TextFieldParser textFieldParser)
    {
        DataTable MethodResult = null;
        try
        {
            textFieldParser.SetDelimiters(new string[] { "," });

            textFieldParser.HasFieldsEnclosedInQuotes = true;


            string[] ColumnFields = textFieldParser.ReadFields();

            DataTable dt = new DataTable();

            foreach (string ColumnField in ColumnFields)
            {
                DataColumn DataColumn = new DataColumn(ColumnField);

                DataColumn.AllowDBNull = true;

                dt.Columns.Add(DataColumn);

            }


            while (!textFieldParser.EndOfData)
            {
                string[] Fields = textFieldParser.ReadFields();


                for (int i = 0; i < Fields.Length; i++)
                {
                    if (Fields[i] == "")
                    {
                        Fields[i] = null;

                    }

                }

                dt.Rows.Add(Fields);

            }

            MethodResult = dt;

        }
        catch (Exception ex)
        {
            ex.HandleException();
        }
        return MethodResult;
    }

    private static DataTable GetDataTableFromTextFieldParserNoHeadings(TextFieldParser textFieldParser)
    {
        DataTable MethodResult = null;
        try
        {
            textFieldParser.SetDelimiters(new string[] { "," });

            textFieldParser.HasFieldsEnclosedInQuotes = true;

            bool FirstPass = true;

            DataTable dt = new DataTable();

            while (!textFieldParser.EndOfData)
            {
                string[] Fields = textFieldParser.ReadFields();

                if(FirstPass)
                {
                    for (int i = 0; i < Fields.Length; i++)
                    {
                        DataColumn DataColumn = new DataColumn("Column " + i);

                        DataColumn.AllowDBNull = true;

                        dt.Columns.Add(DataColumn);

                    }

                    FirstPass = false;

                }

                for (int i = 0; i < Fields.Length; i++)
                {
                    if (Fields[i] == "")
                    {
                        Fields[i] = null;

                    }

                }

                dt.Rows.Add(Fields);

            }

            MethodResult = dt;

        }
        catch (Exception ex)
        {
            ex.HandleException();
        }
        return MethodResult;
    }

如果像我一样，您从报告服务中保存，那么您应该像这样使用它：

    Warning[] warnings;
    string[] streamids;
    string mimeType;
    string encoding;
    string filenameExtension;

    byte[] bytes = rvMain.ServerReport.Render("csv", null, out mimeType, out encoding, out filenameExtension, out streamids, out warnings);

    string CsvBody = System.Text.Encoding.UTF8.GetString(bytes);

    DataTable dt = GetDataTableFromCsvString(CsvBody,true);

否则，您只需要：

    bool IsHeadings = true; //Does the data include a heading row?

    DataTable dt = GetDataTableFromCsvString(CsvBody, IsHeadings);

或直接从csv文件中使用

    bool IsHeadings = true; //Does the data include a heading row?

    DataTable dt = GetDataTabletFromCsvFile(FilePath, IsHeadings)

或者使用远程存储的csv文件

    bool IsHeadings = true; //Does the data include a heading row?

    DataTable dt = GetDataTabletFromRemoteCsv(Url, IsHeadings)

下载csv文件并将其转换为Datatable

3 个答案: