文件/流的加密解密方法

(*
* 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.