未定义对`cv :: imread（cv :: String const＆，int）的引用'

Question

我正在尝试编译一个相对简单的演示应用程序，该应用程序使用dlsym()从库中动态加载函数，并且还包括一些OpenCV函数。 make告诉我：

[100%] Linking CXX executable test
CMakeFiles/test.dir/test.cpp.o: In function `main':
test.cpp:(.text+0x2f8): undefined reference to `cv::imread(cv::String const&, int)'
test.cpp:(.text+0x3e5): undefined reference to `cv::imencode(cv::String const&, cv::_InputArray const&, std::vector<unsigned char, std::allocator<unsigned char> >&, std::vector<int, std::allocator<int> > const&)'
CMakeFiles/test.dir/test.cpp.o: In function `cv::String::String(char const*)':
test.cpp:(.text._ZN2cv6StringC2EPKc[_ZN2cv6StringC5EPKc]+0x4d): undefined reference to `cv::String::allocate(unsigned long)'
CMakeFiles/test.dir/test.cpp.o: In function `cv::String::~String()':
test.cpp:(.text._ZN2cv6StringD2Ev[_ZN2cv6StringD5Ev]+0x14): undefined reference to `cv::String::deallocate()'
CMakeFiles/test.dir/test.cpp.o: In function `cv::Mat::~Mat()':
test.cpp:(.text._ZN2cv3MatD2Ev[_ZN2cv3MatD5Ev]+0x39): undefined reference to `cv::fastFree(void*)'
CMakeFiles/test.dir/test.cpp.o: In function `cv::Mat::release()':
test.cpp:(.text._ZN2cv3Mat7releaseEv[_ZN2cv3Mat7releaseEv]+0x4b): undefined reference to `cv::Mat::deallocate()'
collect2: error: ld returned 1 exit status
CMakeFiles/test.dir/build.make:94: recipe for target 'test' failed
make[2]: *** [test] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/test.dir/all' failed
make[1]: *** [CMakeFiles/test.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2

在致电rm -rf *;cmake -DMAKE_BUILD_TYPE=Release ..之后，我的CMakeLists.txt如下：

ADD_EXECUTABLE (test  test.cpp)
TARGET_LINK_LIBRARIES(test
    ${Open_CV_LIBS}
    #/usr/lib/libalpropencv.so.3
    openalpr
    pthread
    dl
)

我的测试程序的源代码如下：

#include <alpr.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <ios>
#include <dlfcn.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

#define DLSYM 1

int main (void)
{
    void *alprhandle = NULL;
    std::string alprlib = "/usr/lib/libalpropencv.so.3";
#ifdef DLSYM
    typedef void*(*palpr_init_type)(const char*, const char*, const char*, const char*);
            void*(*palpr_init)     (const char*, const char*, const char*, const char*);
    typedef int (*palpr_is_loaded_type)(void*);
            int (*palpr_is_loaded)     (void*);
    typedef alpr::AlprResults (*palpr_recognize_type)(std::vector<char>);
            alpr::AlprResults (*palpr_recognize)     (std::vector<char>);

    //open OpenALPR OpenCV library
    alprhandle = dlopen(alprlib.c_str(), RTLD_NOW);
    if (!alprhandle){
        std::cerr << dlerror() << alprlib <<std::endl;
        exit(0);
    }
    //find the address of functions
    palpr_init = (palpr_init_type)dlsym(alprhandle, "openalpr_init");
    if (!palpr_init)
        std::cerr << "FATAL: Could not find openalpr_init " << dlerror() << std::endl;
    palpr_is_loaded = (palpr_is_loaded_type)dlsym(alprhandle, "openalpr_is_loaded");
    if (!palpr_is_loaded)
        std::cerr << "FATAL: Could not find openalpr_is_loaded " << dlerror() << std::endl;
    palpr_recognize = (palpr_recognize_type)dlsym(alprhandle, "recognize");
    if (!palpr_recognize)
        std::cerr << "FATAL: Could not find recognize " << dlerror() << std::endl;
#endif
    std::string fname = "/path/to/aws/0000024867.jpg";
    std::ifstream is;
    std::ostringstream ss;
#ifdef DLSYM
    void *myinst = NULL;
    myinst = palpr_init("us", "/etc/openalpr/openalpr.conf",NULL,NULL);
#else
    alpr::Alpr openalpr("us", "/etc/openalpr/openalpr.conf");
    openalpr.setTopN(20);
#endif
#ifdef DLSYM
    if (palpr_is_loaded(myinst) == false)
#else
    if (openalpr.isLoaded() == false)
#endif
    {
            std::cerr << "Error loading OpenALPR" << std::endl;
                return 1;
    }

    //is.open(fname.c_str(), std::ios::binary);
    //ss << is.rdbuf();
    const std::string& s = ss.str();
    cv::Mat image = cv::imread(fname.c_str(), CV_LOAD_IMAGE_COLOR);
    std::vector <unsigned char> buff;
    std::vector <int>param = std::vector<int>(2);
    param[0] = cv::IMWRITE_JPEG_QUALITY;
    param[1] = 70;
    imencode(".jpg",image,buff,param);

    std::vector<char> vec(buff.begin(), buff.end());
#ifdef DLSYM
    alpr::AlprResults results = palpr_recognize(vec);
#else
    alpr::AlprResults results = openalpr.recognize(vec);
#endif

    // Carefully observe the results. There may be multiple plates in an image,
    // and each plate returns the top N candidates.
    for (unsigned int i = 0; i < results.plates.size(); i++) {
        alpr::AlprPlateResult plate = results.plates[i];
        std::cout << "plate" << i << ": " << plate.topNPlates.size() << " results" << std::endl;

        for (unsigned int k = 0; k < plate.topNPlates.size(); k++) {
            alpr::AlprPlate candidate = plate.topNPlates[k];
            std::cout << "    - " << candidate.characters << "\t confidence: " <<
            candidate.overall_confidence << std::endl;
        }
    }

    return 0;
}