qt加载dll有四种方式
本例中qt的版本为qt5.11.3 64位
动态加载
使用c++的函数，动态加载
bool bRet = false;
HINSTANCE hDll = nullptr;
hDll = LoadLibraryA("dlfs.dll");
if(hDll != nullptr)
{
bRet = true;
}使用qt自带的QLibrary进行加载
bool bRet = false;
QLibrary liba("dlfs.dll");
if(liba.load)
{
bRet = true;
}静态加载
在pro中添加 lib include 有两种方式
手动?
以配置opencv为例，在pro中直接填写如下内容即可
INCLUDEPATH += $$PWD/3rdparty/opencv/2.4.3/include/
INCLUDEPATH += $$PWD/3rdparty/opencv/2.4.3/include/opencv/
INCLUDEPATH += $$PWD/3rdparty/opencv/2.4.3/include/opencv2/
LIBS += -L$$PWD/3rdparty/opencv/2.4.3/x64/lib/ -lopencv_core243d自动
项目-----添加库---外部库-- 选择 库文件 和 库路径 点击确定后即 在pro中生成如下的内容。
也可以不按照此步骤，直接在pro中添加如下的代码即可
?
?
最后在pro中生成的为：?
INCLUDEPATH += $$PWD/3rdparty/opencv-4.2.0/include
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_core420
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_core420d
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/./3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_imgcodecs420
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_imgcodecs420d
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/./3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_imgproc420
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_imgproc420d
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/./3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_videoio420
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/./3rdparty/opencv-4.2.0/win10/x64/vc15/lib/ -lopencv_videoio420d
qt动态加载dll出现的问题
在使用LoadLibraryA加载动态链接库时，得到的句柄为空
如果发现动态加载dll时 hDll为空，而dll的路径是正确的，这时就要考虑dlff1.dll 的位数与qt程序是否一致了。
HINSTANCE hDll = LoadLibraryA("dlff1.dll");
qt程序为64位，通过dumbin.exe 发现dlff1.dll为32位的，为了使用方便，要求dlff1.dll 改为64位的dll，重新构建项目，输出x64位的dlff1.dll
