zoukankan      html  css  js  c++  java
  • 服务端OLEVARIANT数据之后传输

    将OLEVARIANT数据流化,然后对流进行压缩,还原成OLEVARIANT以后再发送。

    procedure StreamToVariant(Stream: TStream; var V: OLEVariant);
    var
      P : Pointer;
    begin
      try
        V := VarArrayCreate ([0, Stream.Size - 1], varByte);
        P := VarArrayLock (V);
        Stream.Position := 0;
        Stream.Read (P^, Stream.Size);
        VarArrayUnlock (V);
      except
        Exit;
      end;
    end;

    procedure VariantToStream(const V: OLEVariant; Stream: TStream);
    var
      P: Pointer;
    begin
      try
        Stream.Position := 0;
        Stream.Size := VarArrayHighBound (V, 1) - VarArrayLowBound (V, 1) + 1;
        P := VarArrayLock (V);
        Stream.Write (P^, Stream.Size);
        VarArrayUnlock (V);
        Stream.Position := 0;
      except
        Exit;
      end;
    end;

    function CompressData(V: OleVariant): OleVariant;
    var
      M, M0: TMemoryStream;
    begin
      try
        M := TMemoryStream.Create;
        M0 := TMemoryStream.Create;
        try
          if V = Null then exit;
          VariantToStream(V,M);
          M.Position := 0;
          ZCompressStream(M, M0);
          StreamToVariant(M0, V);
        finally
          M.Free;
          M0.Free
        end;
        Result := V;
      except
        Exit;
      end;
    end;

    function DeCompressData(V: OleVariant): OleVariant;
    var
      M, M0: TMemoryStream;
    begin
      try
        M := TMemoryStream.Create;
        M0 := TMemoryStream.Create;
        try
          if V = Null then exit;
          VariantToStream(V,M);
          M.Position := 0;
          ZDeCompressStream(M, M0);
          StreamToVariant(M0, V);      
        finally
          M.Free;
          M0.Free
        end;
        Result := V;
      except
        Exit;
      end;
    end;

  • 相关阅读:
    MVC WebApi的两种访问方法
    MVC CRUD 的两种方法
    MVC EF 导航属性
    MVC EF两种查询方法
    MVC WebApi
    POJ 1511 Invitation Cards ( 双向单源最短路 || 最小来回花费 )
    POJ 2502 Subway ( 最短路 && 最短路建图 )
    POJ 3660 Cow Contest ( 最短路松弛思想应用 && Floyd求传递闭包 )
    POJ 1502 MPI MaeIstrom ( 裸最短路 || atoi系统函数 )
    POJ 3259 Wormholes ( SPFA判断负环 && 思维 )
  • 原文地址:https://www.cnblogs.com/zyb2016/p/11906267.html
Copyright © 2011-2022 走看看