如何在Windows上使用Qt Creator导出并链接到dll？

问题描述

我在Mac上构建了一些Qt项目，目前我正在尝试获取在Windows上构建相同的代码。在这些项目中，有一个dll（称为LibraryA）导出一个由第二个DLL（称为LibraryB）链接到的类（称为ClassA）。

I have got a few Qt projects building on my Mac and I am currently trying to get the same code to build on Windows. In among these projects there is one dll (call it LibraryA) that exports a class (call it ClassA) that is linked to by a second dll (call it LibraryB).

我有以下代码根据所使用的编译器定义要使用的dll导出代码。

I have the following code that defines the dll export code to be used based on the compiler being used.

#ifdef _MSC_VER

    #if defined(LIBRARY_A)
        #define LIBRARY_A_EXPORT __declspec(dllexport)
    #else
        #define LIBRARY_A_EXPORT __declspec(dllimport)
    #endif

#else

    #define LIBRARY_A_EXPORT

#endif

然后将其合并到我的类定义中。

I then incorporate this into my class definitions.

class LIBRARY_A_EXPORT ClassA

但是，在Windows上，我在LibraryB中得到了无法解析的符号__declspec（dllimport）。

However, on Windows I get unresolved symbol __declspec(dllimport) in the LibraryB.

我做错了什么？

编辑我创建了几个独立的项目来尝试使此工作正常（称为LibraryA和LibraryB再次）。 LibraryA成功构建，并且在LibraryB项目中，我使用添加库对话框，选择外部库。这给了我以下仍然不起作用的.pro文件条目

EDIT I created a couple of standalone projects to try and get this working (called LibraryA and LibraryB again). LibraryA successfully builds and in the LibraryB project I used the "Add Library" dialog, selecting External Library. This gives me the following .pro file entries which is still not working

win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../build-LibraryA-Desktop_Qt_5_5_1_MSVC2013_64bit-Debug/release/ -lLibraryA
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../build-LibraryA-Desktop_Qt_5_5_1_MSVC2013_64bit-Debug/debug/ -lLibraryA

INCLUDEPATH += $$PWD/../build-LibraryA-Desktop_Qt_5_5_1_MSVC2013_64bit-Debug/debug
DEPENDPATH += $$PWD/../build-LibraryA-Desktop_Qt_5_5_1_MSVC2013_64bit-Debug/debug

推荐答案

我看到一些可能的情况：

I see a few possible scenarios:

1. 缺少LibraryA.dll（未构建）。可能不是这样。


2. LibraryB无法找到LibraryA。确保在LibraryB'pro'文件中具有正确的库路径： LIBS + = -L $$ PWD / Path_To_LibraryA_Dll / -lLibraryA


3. Library一个项目未定义 LIBRARY_A 宏，并且 LIBRARY_A_EXPORT 未定义为 __ declspec（dllexport），在这种情况下，LibraryA不会导出任何内容供外部使用。确保在LibraryA专业文件中具有定义： DEFINES + = LIBRARY_A

1. LibraryA.dll is missing (not built). Probably not the case.
2. LibraryB is not able to find LibraryA. Make sure you have the proper library path in LibraryB 'pro' file: LIBS += -L$$PWD/Path_To_LibraryA_Dll/ -lLibraryA
3. LibraryA project doesn't have LIBRARY_A macro defined, and the LIBRARY_A_EXPORT doesn't get defined as __declspec(dllexport), in which case, LibraryA won't export anything for external usage. Make sure you have the define in LibraryA 'pro' file: DEFINES += LIBRARY_A

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