(*
* 单元说明: 文件/流的加密解密方法(For Delphi 6-7)
*
* 软件来源: http://www.go-neumann.com
*      http://www.inbytes.net
*
* 作  者: neumann@163.com
*
* 使用说明: 此文件的代码可以直接编译使用,
*      您可以根据需要编写自己的加密/解密代码.
*
* 声  明: 以下代码属作者原创, 请转载时保留本信息.     
*
*)

unit uCompress;

interface

uses
 Windows, Messages, SysUtils, Variants, Classes, ComCtrls, Dialogs;

// 压缩/解压文件
procedure CompressFile(Source, Target: String); stdcall;
procedure DecompressFile(Source, Target: String); stdcall;

// 压缩/解压文件到流
procedure CompressToStream(FileName: String; Stream: TStream); stdcall;
procedure DecompressToStream(FileName: String; Stream: TStream); stdcall;

// 压缩/解压流
procedure CompressStream(InStream, OutStream: TStream); stdcall;
procedure DecompressStream(InStream, OutStream: TStream); stdcall;

implementation

uses
 ZLib;

const
 COMPRESS_ERROR = '压缩文件时出现内部错误:';
 DECOMPRESS_ERROR = '解压文件时出现内部错误:';
 COMPRESS_STRM_ERROR = '压缩流时出现内部错误:';
 DECOMPRESS_STRM_ERROR = '解压流时出现内部错误:'; 
 BufSize = $4096;
 
// 压缩文件
procedure CompressFile(Source, Target: String);
var
 i: Integer;
 Buf: array[0..BufSize] of byte;
 ComStream: TCompressionStream;
 InStream, OutStream: TFileStream;
begin
 if not FileExists(Source) then
  Exit;
 InStream := Nil;
 OutStream := nil;
 ComStream := nil;
 try
  // 生成流
  InStream := TFileStream.Create(Source, fmOpenRead OR fmShareDenyNone);
  OutStream := TFileStream.Create(Target, fmCreate OR fmShareDenyWrite);
  ComStream := TCompressionStream.Create(clMax, OutStream);

  // 压缩流
  for i := 1 to (InStream.Size div BufSize) do begin
   InStream.ReadBuffer(Buf, BufSize);
   ComStream.Write(Buf, BufSize);
  end;

  i := InStream.Size mod BufSize;
  if (i > 0) then begin
   InStream.ReadBuffer(Buf, i);
   ComStream.Write(Buf, i);
  End;

  InStream.Free;
  InStream := nil;

  // 注先后
  ComStream.Free;
  ComStream := nil;

  // 在此写加密流代码(要先释放 ComStream)
  // EncryptStream(OutStream);

  OutStream.Free;
  OutStream := nil;
 except
  on E: Exception do begin
   if (InStream <> nil) then
    InStream.Free;
   if (OutStream <> nil) then
    OutStream.Free;
   if (ComStream <> nil) then
    ComStream.Free;
   MessageDlg(COMPRESS_ERROR + #10 + E.Message, mtError, [mbOk], 0);
  end;
 end;
end;

// 解压文件
procedure DecompressFile(Source, Target: String);
var
 i: Integer;
 Buf: array[0..BufSize] of Byte;
 DecomStream: TDecompressionStream;
 MemStream: TMemoryStream;
 OutStream: TFileStream;
begin
 if not FileExists(Source) then
  Exit;
  
 MemStream := Nil;
 OutStream := nil;
 DecomStream := nil;
 try
  // 生成流
  // 先读文件到 MemStream 中解密(Source 只读).
  // DecomStream 的开始位置 = MemStream.Position
  MemStream := TMemoryStream.Create;
  MemStream.LoadFromFile(Source);
  // 在此写解密流代码
  // DecryptStream(MemStream);

  OutStream := TFileStream.Create(Target, fmCreate or fmShareDenyWrite);
  DecomStream := TDeCompressionStream.Create(MemStream);

{  InStream := TFileStream.Create(Source, fmOpenRead or fmShareDenyNone);
  OutStream := TFileStream.Create(Target, fmCreate or fmShareDenyWrite);
  DecomStream := TDeCompressionStream.Create(InStream); }

  // 解压流
  repeat
   i := DecomStream.Read(Buf, BufSize);
   OutStream.WriteBuffer(Buf, i);
  until (i = 0);

  // 注意先后
  OutStream.Free;
  OutStream := nil;

  DecomStream.Free;
  DecomStream := nil;

  MemStream.Free;
  MemStream := Nil;
 except
  on E: Exception do begin
   if (MemStream <> nil) then
    MemStream.Free;
   if (OutStream <> nil) then
    OutStream.Free;
   if (DecomStream <> nil) then
    DecomStream.Free;
   MessageDlg(DECOMPRESS_ERROR + #10 + E.Message, mtError, [mbOk], 0);
  end;
 end;
end;

// 压缩文件到流
procedure CompressToStream(FileName: String; Stream: TStream);
var
 i: Integer;
 Buf: array[0..BufSize] of byte;
 ComStream: TCompressionStream;
 InStream: TFileStream; 
begin
 if not FileExists(FileName) then
  Exit;
 InStream := Nil;
 ComStream := nil;
 try
  // 生成流
  InStream := TFileStream.Create(FileName, fmOpenRead OR fmShareDenyNone);
  ComStream := TCompressionStream.Create(clMax, Stream);

  // 压缩流
  for i := 1 to (InStream.Size div BufSize) do begin
   InStream.ReadBuffer(Buf, BufSize);
   ComStream.Write(Buf, BufSize);
  end;

  i := InStream.Size mod BufSize;
  if (i > 0) then begin
   InStream.ReadBuffer(Buf, i);
   ComStream.Write(Buf, i);
  End;

  InStream.Free;
  InStream := nil;

  ComStream.Free;
  ComStream := nil;

  // 在此写加密流代码(要先释放 ComStream), Postion = 0
  // EncryptStream(Stream);
 except
  on E: Exception do begin
   if (InStream <> nil) then
    InStream.Free;
   if (ComStream <> nil) then
    ComStream.Free;
   MessageDlg(COMPRESS_ERROR + #10 + E.Message, mtError, [mbOk], 0);
  end;
 end;
end;

// 解压文件到流
procedure DecompressToStream(FileName: String; Stream: TStream);
var
 i: Integer;
 Buf: array[0..BufSize] of Byte;
 DecomStream: TDecompressionStream;
 MemStream: TMemoryStream;
begin
 if not FileExists(FileName) then
  Exit;
 MemStream := Nil;
 DecomStream := nil;
 try
  // 生成流
  // 先读文件到 MemStream 中解密(FileName 只读).
  // DecomStream 的开始位置 = MemStream.Position
  MemStream := TMemoryStream.Create;
  MemStream.LoadFromFile(FileName);

  // 在此写解密流代码
  // DecryptStream(MemStream);

  DecomStream := TDeCompressionStream.Create(MemStream);

  // 解压流, Postion = 0
  repeat
   i := DecomStream.Read(Buf, BufSize);
   Stream.WriteBuffer(Buf, i);
  until (i = 0);
  Stream.Position := 0;

  DecomStream.Free;
  DecomStream := nil;

  MemStream.Free;
  MemStream := Nil;
 except
  on E: Exception do begin
   if (MemStream <> nil) then
    MemStream.Free;
   if (DecomStream <> nil) then
    DecomStream.Free;
   MessageDlg(DECOMPRESS_ERROR + #10 + E.Message, mtError, [mbOk], 0);
  end;
 end;
end;

// 压缩流
procedure CompressStream(InStream, OutStream: TStream);
var
 i: Integer;
 Buf: array[0..BufSize] of byte;
 ComStream: TCompressionStream;
begin
 ComStream := Nil;
 try
  InStream.Position := 0;
  ComStream := TCompressionStream.Create(clMax, OutStream);

  for i := 1 to (InStream.Size div BufSize) do begin
   InStream.ReadBuffer(Buf, BufSize);
   ComStream.Write(Buf, BufSize);
  end;

  i := InStream.Size mod BufSize;
  if (i > 0) then begin
   InStream.ReadBuffer(Buf, i);
   ComStream.Write(Buf, i);
  End;

  ComStream.Free;
  ComStream := nil;

  // 在此写加密流代码
  // EncryptStream(OutStream);
 except
  on E: Exception do begin
   if (ComStream <> nil) then
    ComStream.Free;
   MessageDlg(COMPRESS_STRM_ERROR + #10 + E.Message, mtError, [mbOk], 0);
  end;
 end;
end;

// 解压流
procedure DecompressStream(InStream, OutStream: TStream);
var
 i: Integer;
 Buf: array[0..BufSize] of Byte;
 DecomStream: TDecompressionStream;
begin
 DecomStream := nil;
 try
  // 在此写解密流代码
  // DecryptStream(InStream);
  DecomStream := TDeCompressionStream.Create(InStream);

  repeat
   i := DecomStream.Read(Buf, BufSize);
   OutStream.WriteBuffer(Buf, i);
  until (i = 0);
  OutStream.Position := 0;

  DecomStream.Free;
  DecomStream := nil;
 except
  on E: Exception do begin
   if (DecomStream <> nil) then
    DecomStream.Free;
   MessageDlg(DECOMPRESS_STRM_ERROR + #10 + E.Message, mtError, [mbOk], 0);
  end;
 end;
end;

end.

（出处：http://www.go-neumann.com）