将[字节数组]分配给没有Unicode转换的Variant [英] Assign [array of byte] to a Variant with no Unicode conversion

问题描述

考虑以下代码段(在Delphi XE2中):

Consider the following code snippet (in Delphi XE2):

function PrepData(StrVal: string; Base64Val: AnsiString): OleVariant;
begin
  Result := VarArrayCreate([0, 1], varVariant);
  Result[0] := StrVal;
  Result[1] := Base64Val;
end;

Base64Val是一个二进制值，编码为Base64(因此没有null字节). (OleVariant)结果将自动编组并在客户端应用程序和DataSnap服务器之间发送.

Base64Val is a binary value encoded as Base64 (so no null bytes). The (OleVariant) Result is automatically marshalled and sent between a client app and a DataSnap server.

当我使用Wireshark捕获流量时，我看到StrVal和Base64Val均作为Unicode字符串传输.如果可以，我想避免Base64Val的Unicode转换.我已经看过所有Variant类型，除了varString之外没有其他可以传输字符数组的东西.

When I capture the traffic with Wireshark, I see that both StrVal and Base64Val are transferred as Unicode strings. If I can, I would like to avoid the Unicode conversion for Base64Val. I've looked at all the Variant types and don't see anything other than varString that can transfer an array of characters.

我发现了这个问题，该问题显示了如何创建字节的变体数组.我在想可以使用此技术代替使用AnsiString.不过，我很好奇，是否有另一种方法可以将非Unicode字符数据数组分配给Variant，而无需转换为Unicode字符串?

I found this question that shows how to create a variant array of bytes. I'm thinking that I could use this technique instead of using an AnsiString. I'm curious though, is there another way to assign an array of non-Unicode character data to a Variant without a conversion to a Unicode string?

推荐答案

Delphi的实现支持使用自定义变量类型代码将AnsiString和UnicodeString存储在Variant中.这些代码是varString和varUString.

Delphi's implementation supports storing AnsiString and UnicodeString in a Variant, using custom variant type codes. These codes are varString and varUString.

但是互操作通常会使用标准OLE变体，并且OLE字符串varOleStr是16位编码的.这似乎就是您进行观察的原因.

But interop will typically use standard OLE variants and the OLE string, varOleStr, is 16 bit encoded. That would seem to be the reason for your observation.

如果您希望避免转换为16位文本，则需要将数据作为字节数组放置.这样做会使base64编码变得毫无意义.停止对有效负载进行base64编码，然后将二进制文件发送到字节数组中.

You'll need to put the data in as an array of bytes if you do wish to avoid a conversion to 16 bit text. Doing so renders base64 encoding pointless. Stop base64 encoding the payload and send the binary in a byte array.

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