如何把多个文件写入到一个文件中去并能分解

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如何把多个文件写入到一个文件中去并能分解

时间: 2008-03-19 00:49

对于一个文件的读写，其实很简单，就是用FileStream进行Read或者Write就行了。但是如何把多个文件写入到同一个文件，之后要能把这个文件进行还原成多个文件。那么光靠FileStream的Read和Write方法是不够的，首先你需要自行建立文件索引，来标明每个文件在当前文件的位置。

对于一个文件的读写，其实很简单，就是用FileStream进行Read或者Write就行了。但是如何把多个文件写入到同一个文件，之后要能把这个文件进行还原成多个文件。那么光靠FileStream的Read和Write方法是不够的，首先你需要自行建立文件索引，来标明每个文件在当前文件的位置。

那么最近作了一个简单的DEMO，其中类的部分代码如下：

//------------------------------- Compose Files ----------------------------------

//--------------------------------------------------------------------------------

//---File:clsComposeFiles.cs

//---Descriptionhis file is to show how-to compose multi-files into one file

//
and decompose one file to multi-files.

//---Author:Knight

//---Date:May.16, 2006

//--------------------------------------------------------------------------------

//------------------------------{ Compose Files }---------------------------------

namespace ComposeFiles

{

using System;

using System.IO;

using System.Collections;

using System.Text;

///
<summary>

/// Summary description for clsComposeFiles.

///
</summary>

public class clsComposeFiles

{

private ArrayList arrFiles = new ArrayList();

public clsComposeFiles()

{

// TODO: Add constructor logic here

}

///
<summary>

/// Add a file to be composed

///
</summary>

///
<param name="sFileName"></param>

public void AddFile( string sFileName )

{

arrFiles.Add( sFileName );

}

///
<summary>

/// Compose files to the specific file

///
</summary>

///
<param name="sFileName"></param>

///
<returns></returns>

public bool ComposeFiles( string sFileName )

{

if( arrFiles.Count == 0 ) return false;

FileInfo fi = new FileInfo( sFileName );

// Open file to write

FileStream fsWriter = null;

try

{

if( !fi.Exists )

{

fsWriter = new FileStream(

sFileName,

FileMode.CreateNew,

FileAccess.ReadWrite,

FileShare.None );

}

else

fsWriter = new FileStream(

sFileName,

FileMode.Truncate,

FileAccess.ReadWrite,

FileShare.None );

}

catch(Exception err)

{

System.Diagnostics.Debug.WriteLine( err.Message );

return false;

}

byte[] bBuffer = null;

// Write files count

bBuffer = FileIndex.LongToBytes( arrFiles.Count );

fsWriter.Write( bBuffer, 0, 8 );

const long INDEX_START_POS = 8L;

// Init files index

FileIndex FI = new FileIndex();

for( int i = 0; i < arrFiles.Count; i++ )

fsWriter.Write( FileIndex.ConvertToBytes( ref FI ), 0, 32 );

long FILE_START_POS = INDEX_START_POS + 32 * arrFiles.Count;

long lCurFileStartPos = FILE_START_POS;

// Write every file

for( int i = 0; i < arrFiles.Count; i++ )

{

WriteFile( arrFiles.ToString(),

ref lCurFileStartPos,

INDEX_START_POS,

fsWriter,

i );

}

// Close stream

fsWriter.Close();

return true;

}

///
<summary>

/// Write file name and data into composed file

///
</summary>

///
<param name="sFileName"></param>

///
<param name="FileStartPos"></param>

///
<param name="IndexStartPos"></param>

///
<param name="fsWriter"></param>

///
<param name="Index"></param>

private void WriteFile(

string sFileName,

ref long FileStartPos,

long IndexStartPos,

FileStream fsWriter,

int Index )

{

FileInfo fi = new FileInfo( sFileName );

if( !fi.Exists ) return;

FileStream fsReader = null;

try

{

fsReader = new FileStream(

sFileName, FileMode.Open,

FileAccess.Read );

}

catch{ return;}

// Get file name

byte[] bFileName = Encoding.Unicode.GetBytes( fi.Name );

// Write file name

fsWriter.Write( bFileName, 0, bFileName.Length );

const int BUFFER_LENGTH = 1024;

byte[] bBuffer = new byte[BUFFER_LENGTH];

int nRealRead = 0;

// Write data using

do

{

// Read data from file

nRealRead = fsReader.Read( bBuffer, 0,

BUFFER_LENGTH );

// Write data

fsWriter.Write( bBuffer, 0, nRealRead );

}while( nRealRead > 0 );

// Close file reader

fsReader.Close();

FileIndex FINew = new FileIndex();

FINew.NameStartPos = FileStartPos;

FINew.NameLength = bFileName.Length;

FINew.FileStartPos = FileStartPos + bFileName.Length;

FINew.FileLength = fi.Length;

// Go back to file index position

fsWriter.Seek( IndexStartPos + Index * 32, SeekOrigin.Begin );

// Write file index info

fsWriter.Write( FileIndex.ConvertToBytes( ref FINew ), 0, 32 );

// Go back to file end

fsWriter.Seek( 0, SeekOrigin.End );

// Set file current position

FileStartPos += bFileName.Length + fi.Length;

}

///
<summary>

/// Decompose file to multi files into specific directory

///
</summary>

///
<param name="sFileName"></param>

///
<param name="sDestDir"></param>

///
<returns></returns>

public bool DecomposeFile( string sFileName, string sDestDir )

{

FileInfo fi = new FileInfo( sFileName );

if( !fi.Exists ) return false;

FileStream fsReader = null;

try

{

fsReader = new FileStream(

sFileName, FileMode.Open,

FileAccess.Read );

}

catch{ return false;}

// Read file count

byte[] bFileCount = new byte[8];

int nRealRead = 0;

nRealRead = fsReader.Read( bFileCount, 0, 8 );

if( nRealRead != 8 )

{

fsReader.Close();

return false;

}

long lFileCount = FileIndex.BytesToLong( bFileCount );

if( lFileCount > 0 )

{

//Init file index array

FileIndex[] fiArray = new FileIndex[lFileCount];

byte[] bFileIndex = new byte[32];

for( int i = 0; i < lFileCount; i++ )

{

fsReader.Read( bFileIndex, 0, 32 );

fiArray = FileIndex.ConvertToFileIndex( bFileIndex );

}

if( sDestDir[ sDestDir.Length - 1] != '\\' )

sDestDir += "\\";

// Save every file into current directory

for( int i = 0; i < fiArray.Length; i++ )

{

SaveFile( fsReader,

ref fiArray,

sDestDir );

}

}

// Close file reader

fsReader.Close();

return true;

}

///
<summary>

/// Save every file into directory

///
</summary>

///
<param name="fsReader"></param>

///
<param name="FI"></param>

///
<param name="sDestDir"></param>

private void SaveFile(

FileStream fsReader,

ref FileIndex FI,

string sDestDir )

{

// Read file name

byte[] bFileName = new byte[ FI.NameLength ];

int nRealRead = fsReader.Read( bFileName, 0, bFileName.Length );

if( nRealRead != bFileName.Length ) return;

string sFileName = Encoding.Unicode.GetString( bFileName );

sFileName = sDestDir + sFileName;

FileInfo fi = new FileInfo( sFileName );

// Open file to write

FileStream fsWriter = null;

try

{

if( !fi.Exists )

{

fsWriter = new FileStream(

sFileName,

FileMode.CreateNew,

FileAccess.ReadWrite,

FileShare.None );

}

else

fsWriter = new FileStream(

sFileName,

FileMode.Truncate,

FileAccess.ReadWrite,

FileShare.None );

}

catch(Exception err){

System.Diagnostics.Debug.WriteLine( err.Message );

return;

}

// Init buffer

const int BUFFER_LENGTH = 1024;

byte[] bBuffer = new byte[BUFFER_LENGTH];

long lLeft = FI.FileLength;

// Copy file

do

{

if( lLeft > BUFFER_LENGTH )

{

fsReader.Read( bBuffer, 0, BUFFER_LENGTH );

fsWriter.Write( bBuffer, 0, BUFFER_LENGTH );

lLeft -= BUFFER_LENGTH;

}

else

{

nRealRead = fsReader.Read( bBuffer, 0, (int)lLeft );

fsWriter.Write( bBuffer, 0, nRealRead );

lLeft -= nRealRead;

}

}

while( lLeft > 0 );