T
At the time, we had to export a bunch of dbf files.
I found this class.code at the end of question)in essence:DataTable table=ParseDBF.ReadDBF(fileName);
In most cases, cp866 and cp1251 were well read.Code:using System;
using System.Collections;
using System.Data;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using System.Globalization;
// Read an entire standard DBF file into a DataTable
public class ParseDBF
{
// This is the file header for a DBF. We do this special layout with everything
// packed so we can read straight from disk into the structure to populate it
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
private struct DBFHeader
{
public byte version;
public byte updateYear;
public byte updateMonth;
public byte updateDay;
public Int32 numRecords;
public Int16 headerLen;
public Int16 recordLen;
public Int16 reserved1;
public byte incompleteTrans;
public byte encryptionFlag;
public Int32 reserved2;
public Int64 reserved3;
public byte MDX;
public byte language;
public Int16 reserved4;
}
// This is the field descriptor structure. There will be one of these for each column in the table.
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
private struct FieldDescriptor
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 11)]
public string fieldName;
public char fieldType;
public Int32 address;
public byte fieldLen;
public byte count;
public Int16 reserved1;
public byte workArea;
public Int16 reserved2;
public byte flag;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 7)]
public byte[] reserved3;
public byte indexFlag;
}
public static string ConvertString(string value, Encoding src, Encoding trg)
{
Decoder dec = src.GetDecoder();
byte[] ba = trg.GetBytes(value);
int len = dec.GetCharCount(ba, 0, ba.Length);
char[] ca = new char[len];
dec.GetChars(ba, 0, ba.Length, ca, 0);
return new string(ca);
}
public static string ConvertString(byte[] value, Encoding src, Encoding trg)
{
Decoder dec = src.GetDecoder();
byte[] ba = value;
int len = dec.GetCharCount(ba, 0, ba.Length);
char[] ca = new char[len];
dec.GetChars(ba, 0, ba.Length, ca, 0);
return new string(ca);
}
// Read an entire standard DBF file into a DataTable
public static DataTable ReadDBF(string dbfFile)
{
long start = DateTime.Now.Ticks;
DataTable dt = new DataTable();
BinaryReader recReader;
string number;
string year;
string month;
string day;
long lDate;
long lTime;
DataRow row;
int fieldIndex;
// If there isn't even a file, just return an empty DataTable
if ((false == File.Exists(dbfFile)))
{
return dt;
}
BinaryReader br = null;
try
{
// Read the header into a buffer
br = new BinaryReader(File.OpenRead(dbfFile));
byte[] buffer = br.ReadBytes(Marshal.SizeOf(typeof(DBFHeader)));
// Marshall the header into a DBFHeader structure
GCHandle handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
DBFHeader header = (DBFHeader)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(DBFHeader));
handle.Free();
// Read in all the field descriptors. Per the spec, 13 (0D) marks the end of the field descriptors
ArrayList fields = new ArrayList();
while ((13 != br.PeekChar()))
{
buffer = br.ReadBytes(Marshal.SizeOf(typeof(FieldDescriptor)));
handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
fields.Add((FieldDescriptor)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(FieldDescriptor)));
handle.Free();
}
// Read in the first row of records, we need this to help determine column types below
((FileStream)br.BaseStream).Seek(header.headerLen + 1, SeekOrigin.Begin);
buffer = br.ReadBytes(header.recordLen);
recReader = new BinaryReader(new MemoryStream(buffer));
// Create the columns in our new DataTable
DataColumn col = null;
foreach (FieldDescriptor field in fields)
{
number = Encoding.ASCII.GetString(recReader.ReadBytes(field.fieldLen));
switch (field.fieldType)
{
case 'N':
if (number.IndexOf(".") > -1)
{
col = new DataColumn(field.fieldName, typeof(decimal));
}
else
{
col = new DataColumn(field.fieldName, typeof(int));
}
break;
case 'C':
col = new DataColumn(field.fieldName, typeof(string));
break;
case 'T':
// You can uncomment this to see the time component in the grid
//col = new DataColumn(field.fieldName, typeof(string));
col = new DataColumn(field.fieldName, typeof(DateTime));
break;
case 'D':
col = new DataColumn(field.fieldName, typeof(DateTime));
break;
case 'L':
col = new DataColumn(field.fieldName, typeof(bool));
break;
case 'F':
col = new DataColumn(field.fieldName, typeof(Double));
break;
case '0':
col = null;
break;
}
if (col!=null)
dt.Columns.Add(col);
}
// Skip past the end of the header.
((FileStream)br.BaseStream).Seek(header.headerLen, SeekOrigin.Begin);
// Read in all the records
for (int counter = 0; counter <= header.numRecords - 1; counter++)
{
// First we'll read the entire record into a buffer and then read each field from the buffer
// This helps account for any extra space at the end of each record and probably performs better
buffer = br.ReadBytes(header.recordLen);
recReader = new BinaryReader(new MemoryStream(buffer));
// All dbf field records begin with a deleted flag field. Deleted - 0x2A (asterisk) else 0x20 (space)
if (recReader.ReadChar() == '*')
{
continue;
}
// Loop through each field in a record
fieldIndex = 0;
row = dt.NewRow();
foreach (FieldDescriptor field in fields)
{
switch (field.fieldType)
{
case 'N': // Number
// If you port this to .NET 2.0, use the Decimal.TryParse method
number = Encoding.ASCII.GetString(recReader.ReadBytes(field.fieldLen));
if (IsNumber(number))
{
if (number.IndexOf(".") > -1)
{
//row[fieldIndex] = decimal.Parse(number);
row[fieldIndex] = GetDoubleFromString(number);
}
else
{
row[fieldIndex] = GetDoubleFromString(number);
}
}
else
{
row[fieldIndex] = 0;
}
break;
case 'C': // String
//number = ConvertString(number, Encoding.GetEncoding(866), Encoding.Default);
//string value =recReader.ReadBytes(field.fieldLen).ToString();
//row[fieldIndex] = recReader.ReadBytes(field.fieldLen).ToString();
//byte[] tmp = recReader.ReadBytes(field.fieldLen);
//string temp1 = ConvertString(tmp, Encoding.ASCII, Encoding.Default);
//temp1 = ConvertString(tmp, Encoding.GetEncoding(866), Encoding.Default);
//temp1 = ConvertString(tmp, Encoding.GetEncoding(1251), Encoding.Default);
//temp1 = ConvertString(tmp, Encoding.GetEncoding(1251), Encoding.GetEncoding(866));
//temp1 = ConvertString(tmp, Encoding.GetEncoding(866), Encoding.GetEncoding(1251));
//temp1 = ConvertString(tmp, Encoding.ASCII, Encoding.GetEncoding(866));
//temp1 = ConvertString(tmp, Encoding.ASCII, Encoding.GetEncoding(1251));
row[fieldIndex] = ConvertString(recReader.ReadBytes(field.fieldLen), Encoding.GetEncoding(866), Encoding.GetEncoding(866));
//row[fieldIndex] = Encoding.Convert(Encoding.GetEncoding(866), Encoding.GetEncoding(1251), recReader.ReadBytes(field.fieldLen));
break;
case 'D': // Date (YYYYMMDD)
year = Encoding.ASCII.GetString(recReader.ReadBytes(4));
month = Encoding.ASCII.GetString(recReader.ReadBytes(2));
day = Encoding.ASCII.GetString(recReader.ReadBytes(2));
row[fieldIndex] = System.DBNull.Value;
try
{
if (IsNumber(year) && IsNumber(month) && IsNumber(day))
{
if ((Int32.Parse(year) > 1900))
{
row[fieldIndex] = new DateTime(Int32.Parse(year), Int32.Parse(month), Int32.Parse(day));
}
}
}
catch
{ }
break;
case 'T': // Timestamp, 8 bytes - two integers, first for date, second for time
// Date is the number of days since 01/01/4713 BC (Julian Days)
// Time is hours * 3600000L + minutes * 60000L + Seconds * 1000L (Milliseconds since midnight)
lDate = recReader.ReadInt32();
lTime = recReader.ReadInt32() * 10000L;
row[fieldIndex] = JulianToDateTime(lDate).AddTicks(lTime);
break;
case 'L': // Boolean (Y/N)
if ('Y' == recReader.ReadByte())
{
row[fieldIndex] = true;
}
else
{
row[fieldIndex] = false;
}
break;
case 'F':
number = Encoding.ASCII.GetString(recReader.ReadBytes(field.fieldLen));
if (IsNumber(number))
{
//row[fieldIndex] = double.Parse(number);
row[fieldIndex] = GetDoubleFromString(number);
}
else
{
//row[fieldIndex] = 0.0F;
row[fieldIndex] = GetDoubleFromString(number);
}
break;
}
fieldIndex++;
}
recReader.Close();
dt.Rows.Add(row);
}
}
catch
{
//throw;
}
finally
{
if (null != br)
{
br.Close();
}
}
long count = DateTime.Now.Ticks - start;
return dt;
}
/// <summary>
/// Simple function to test is a string can be parsed. There may be a better way, but this works
/// If you port this to .NET 2.0, use the new TryParse methods instead of this
/// *Thanks to wu.qingman on code project for fixing a bug in this for me
/// </summary>
/// <param name="number">string to test for parsing</param>
/// <returns>true if string can be parsed</returns>
#region GetDoubleFromString(String aStr)
private static Double GetDoubleFromString(String aStr)
{
// Подготавливаем строку
aStr = aStr.Trim(new char[] { '(', ')', ' ' });
// Временная переменная
Double tmpd = 0;
// Получаем текущие настройки
var format = new System.Globalization.NumberFormatInfo();
// Пытаемся преобразовать строку в число
if (!Double.TryParse(aStr, NumberStyles.Float, format, out tmpd))
{
if (format.NumberDecimalSeparator == ",")
format.NumberDecimalSeparator = ".";
else if (format.NumberDecimalSeparator == ".")
format.NumberDecimalSeparator = ",";
// Если всеравно не удалось то возвращаем -1
if (!Double.TryParse(aStr, NumberStyles.Float, format, out tmpd))
return -1;
}
return tmpd;
}
#endregion
public static bool IsNumber(string numberString)
{
char[] numbers = numberString.ToCharArray();
int number_count = 0;
int point_count = 0;
int space_count = 0;
foreach (char number in numbers)
{
if ((number >= 48 && number <= 57))
{
number_count += 1;
}
else if (number == 46)
{
point_count += 1;
}
else if (number == 32)
{
space_count += 1;
}
else
{
return false;
}
}
return (number_count > 0 && point_count < 2);
}
/// <summary>
/// Convert a Julian Date to a .NET DateTime structure
/// Implemented from pseudo code at http://en.wikipedia.org/wiki/Julian_day
/// </summary>
/// <param name="lJDN">Julian Date to convert (days since 01/01/4713 BC)</param>
/// <returns>DateTime</returns>
private static DateTime JulianToDateTime(long lJDN)
{
double p = Convert.ToDouble(lJDN);
double s1 = p + 68569;
double n = Math.Floor(4 * s1 / 146097);
double s2 = s1 - Math.Floor((146097 * n + 3) / 4);
double i = Math.Floor(4000 * (s2 + 1) / 1461001);
double s3 = s2 - Math.Floor(1461 * i / 4) + 31;
double q = Math.Floor(80 * s3 / 2447);
double d = s3 - Math.Floor(2447 * q / 80);
double s4 = Math.Floor(q / 11);
double m = q + 2 - 12 * s4;
double j = 100 * (n - 49) + i + s4;
return new DateTime(Convert.ToInt32(j), Convert.ToInt32(m), Convert.ToInt32(d));
}
}
