检校MD5

uses IdHashMessageDigest, IdHash; 

{ 从流中校验数据的MD5值 }

function MD5Stream(const Stream: TStream): string;
var
  MyMD5: TIdHashMessageDigest5;
  Digest: T4x4LongWordRecord;
begin
  Result := '';
  try
    try
      MyMD5 := TIdHashMessageDigest5.Create;
      Stream.Position := 0;
      Digest := MyMD5.HashValue(Stream);
      Stream.Position := 0;
      Result := MyMD5.AsHex(Digest);
    except
      Result := '';
    end;
  finally
    if Assigned(MyMD5) then
      FreeAndNil(MyMD5);
  end;
end;

{ 校验文件的MD5值 }

function MD5File(const LocalFile: string): string;
var
  Stream: TFileStream;
begin
  Result := '';
  if not FileExists(LocalFile) then
    exit;
  try
    try
      Stream := TFileStream.Create(LocalFile, fmOpenRead);
      Result := MD5Stream(Stream);
    except
      Result := '';
    end;
  finally
    if Assigned(Stream) then
      FreeAndNil(Stream)
  end;
end;

{ 检校字符串MD5 }

function MD5String(const Src: string): string;
var
  MyMD5: TIdHashMessageDigest5;
  Digest: T4x4LongWordRecord;
begin
  Result := '';
  try
    try
      MyMD5 := TIdHashMessageDigest5.Create;
      Digest := MyMD5.HashValue(Src);
      Result := MyMD5.AsHex(Digest);
    except
      Result := '';
    end;
  finally
    if Assigned(MyMD5) then
      FreeAndNil(MyMD5);
  end;
end;