//delphi利用文件流把文件拆分与合并

procedure SplitFile(FileName : TFileName; FilesByteSize : Integer) ;
// FileName == file to split into several smaller files
// FilesByteSize == the size of files in bytes
var
fs, ss: TFileStream;
cnt : integer;
SplitName: String;
begin
fs := TFileStream.Create(FileName, fmOpenRead or fmShareDenyWrite) ;
try
for cnt := 1 to Trunc(fs.Size / FilesByteSize) + 1 do
begin
SplitName := ChangeFileExt(FileName, Format('%s%d', ['._',cnt])) ;
ss := TFileStream.Create(SplitName, fmCreate or fmShareExclusive) ;
try
if fs.Size - fs.Position < FilesByteSize then
FilesByteSize := fs.Size - fs.Position;
ss.CopyFrom(fs, FilesByteSize) ;
finally
ss.Free;
end;
end;
finally
fs.Free;
end;
end;

Note: a 3 KB file 'myfile.ext' will be split into 'myfile._1', 'myfile._2','myfile._3' if FilesByteSize parameter equals 1024 (1 KB).

procedure MergeFiles(FirstSplitFileName, OutFileName : TFileName) ;
// FirstSplitFileName == the name of the first piece of the split file
// OutFileName == the name of the resulting merged file
var
fs, ss: TFileStream;
cnt: integer;
begin
cnt := 1;
fs := TFileStream.Create(OutFileName, fmCreate or fmShareExclusive) ;
try
while FileExists(FirstSplitFileName) do
begin
ss := TFileStream.Create(FirstSplitFileName, fmOpenRead or fmShareDenyWrite) ;
try
fs.CopyFrom(ss, 0) ;
finally
ss.Free;
end;
Inc(cnt) ;
FirstSplitFileName := ChangeFileExt(FirstSplitFileName, Format('%s%d', ['._',cnt])) ;
end;
finally
fs.Free;
end;
end;

Usage:
SplitFile('c:\mypicture.bmp', 1024) ; //into 1 KB files
...
MergeFiles('c:\mypicture._1','c:\mymergedpicture.bmp') ;