从固定长度文件中读取数据到类对象中 [英] Reading data from Fixed Length File into class objects
问题描述
我有一个固定长度的文件，想将其数据读入类对象.这些对象将进一步用于在数据库中插入/更新数据.尽管可以使用StreamReader完成，但我正在寻找更高级的解决方案. FileHelper是另一个解决方案，但我不想在程序中使用开放源代码.还有其他选择吗?
I have a fixed length file and would like to read its data into class objects. These objects will be further used to insert/update data in Database. Although it can be done with StreamReader, I am looking for a more sophisticated solution. FileHelper is another solution but I do not want to use an open source code in my program. Is there any other option?
在下面的链接中，一个用户回答了类似的问题，但未详细说明:
In the below link, one user has answered this similar question but it is not elaborated:
https://codereview.stackexchange.com /questions/27782/如何在网中读取固定宽度的数据字段
我尝试实现此功能，但是找不到Layout()属性.
I tried to implement this but I am unable to find Layout() Attribute.
谢谢.
样本定长文件:
aCSTDCECHEUR20140701201409161109 //Header of the file
b0000000000050115844085700800422HB HERBOXAN-COMPACT WHITE 12,5L 0000002297P0000000184L0000000000 0000000000
zCSTDCECH201409161109 148 //Footer of the file
推荐答案
我不知道您的数据如何序列化(您未指定任何协议或数据描述)；但是您说过，为其他问题精心设计解决方案将解决您的问题.我对此进行详细说明:您很容易更改实现，以便根据您的格式解析数据(而不是像下面的示例中那样使用二进制流).
I don't know how your data was serialized (you are not specifying any protocol nor data description); however you said that an elaboration of solution for the other question would solve your issue. I'm giving you an elaboration for that: it will be easy for you to change my implementation so that data will be parsed according to your format (instead of using a binary stream, as I did in the following example).
我认为，在您提到的问题中，他们建议实施自己的属性以获取解决方案.
I think that in the question you are referring to, they were suggesting to implement their own attributes in order to obtain the solution.
我可以在此处给出一个实现示例(仅是一个示例，请在生产前对其进行编辑...):
I can give an example of implementation here (it's just an example, edit it before production use...):
包含您的数据结构的文件:
File containing your data structure:
//MyData.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace FixedLengthFileReader
{
class MyData
{
[Layout(0, 10)]
public string field1;
[Layout(10, 4)]
public int field2;
[Layout(14, 8)]
public double field3;
public override String ToString() {
return String.Format("String: {0}; int: {1}; double: {2}", field1, field2, field3);
}
}
}
属性:
// LayoutAttribute.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace FixedLengthFileReader
{
[AttributeUsage(AttributeTargets.Field)]
class LayoutAttribute : Attribute
{
private int _index;
private int _length;
public int index
{
get { return _index; }
}
public int length
{
get { return _length; }
}
public LayoutAttribute(int index, int length)
{
this._index = index;
this._length = length;
}
}
}
阅读器实现示例:
//FixedLengthReader.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Reflection;
namespace FixedLengthFileReader
{
class FixedLengthReader
{
private Stream stream;
private byte[] buffer;
public FixedLengthReader(Stream stream)
{
this.stream = stream;
this.buffer = new byte[4];
}
public void read<T>(T data)
{
foreach (FieldInfo fi in typeof(T).GetFields())
{
foreach (object attr in fi.GetCustomAttributes())
{
if (attr is LayoutAttribute)
{
LayoutAttribute la = (LayoutAttribute)attr;
stream.Seek(la.index, SeekOrigin.Begin);
if (buffer.Length < la.length) buffer = new byte[la.length];
stream.Read(buffer, 0, la.length);
if (fi.FieldType.Equals(typeof(int)))
{
fi.SetValue(data, BitConverter.ToInt32(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(bool)))
{
fi.SetValue(data, BitConverter.ToBoolean(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(string)))
{
// --- If string was written using UTF8 ---
byte[] tmp = new byte[la.length];
Array.Copy(buffer, tmp, tmp.Length);
fi.SetValue(data, System.Text.Encoding.UTF8.GetString(tmp));
// --- ALTERNATIVE: Chars were written to file ---
//char[] tmp = new char[la.length - 1];
//for (int i = 0; i < la.length; i++)
//{
// tmp[i] = BitConverter.ToChar(buffer, i * sizeof(char));
//}
//fi.SetValue(data, new string(tmp));
}
else if (fi.FieldType.Equals(typeof(double)))
{
fi.SetValue(data, BitConverter.ToDouble(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(short)))
{
fi.SetValue(data, BitConverter.ToInt16(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(long)))
{
fi.SetValue(data, BitConverter.ToInt64(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(float)))
{
fi.SetValue(data, BitConverter.ToSingle(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(ushort)))
{
fi.SetValue(data, BitConverter.ToUInt16(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(uint)))
{
fi.SetValue(data, BitConverter.ToUInt32(buffer, 0));
}
else if (fi.FieldType.Equals(typeof(ulong)))
{
fi.SetValue(data, BitConverter.ToUInt64(buffer, 0));
}
}
}
}
}
}
}
最后是程序实现的示例(非常简单):
And finally an example of program implementation (very simple):
// Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
namespace FixedLengthFileReader
{
class Program
{
static void Main(string[] args)
{
MyData md = new MyData();
Console.WriteLine(md);
Stream s = File.OpenRead("testFile.bin");
FixedLengthReader flr = new FixedLengthReader(s);
flr.read(md);
s.Close();
Console.WriteLine(md);
}
}
}
如果要针对示例二进制文件测试该代码，则可以使用以下十六进制代码创建文件:
If you want to test that code against an example binary file, you could create a file with the following hex code:
41 42 43 44 45 46 47 48 49 4A 01 00 00 00 00 00 00
00 00 00 E0 3F
哪个代表以下字节:
- 字符串ABCDEFGHIJ(10个字节)
- 整数1(4个字节)
- 0.5的两倍(8个字节)
(我使用XVI32创建了一个文件，添加了十六进制代码并将其保存为testFile.bin)
(I created a file using XVI32, adding that hex code and saving it as testFile.bin)
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