QT共享库未定义的引用

Question

我正在学习在QT中链接共享库，尝试教程，但没有任何作用。有人能帮我找出错误吗?

当我编译我的测试项目时，我有一个错误"未定义的测试引用"。

项目，我试图链接我的lib:loadTestLib.pro:

#-------------------------------------------------
#
# Project created by QtCreator 2013-04-22T15:32:30
#
#-------------------------------------------------
QT       += core
QT       -= gui
TARGET = loadTestLib
CONFIG   += console
CONFIG   -= app_bundle
TEMPLATE = app

SOURCES += main.cpp
LIBS+=-L../libtest.so.1.0.0
HEADERS += 
    test_global.h 
    test.h

main.cpp:

#include <QCoreApplication>
#include "test.h"
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    Test test;
    return a.exec();
}

test_global.h:

#ifndef TEST_GLOBAL_H
#define TEST_GLOBAL_H
#include <QtCore/qglobal.h>
#if defined(TEST_LIBRARY)
#  define TESTSHARED_EXPORT Q_DECL_EXPORT
#else
#  define TESTSHARED_EXPORT Q_DECL_IMPORT
#endif
#endif // TEST_GLOBAL_H

test.h:

#ifndef TEST_H
#define TEST_H
#include "test_global.h"
class TESTSHARED_EXPORT Test
{
public:
    Test();
};
#endif // TEST_H

库:

test_global.h:

#ifndef TEST_GLOBAL_H
#define TEST_GLOBAL_H
#include <QtCore/qglobal.h>
#if defined(TEST_LIBRARY)
#  define TESTSHARED_EXPORT Q_DECL_EXPORT
#else
#  define TESTSHARED_EXPORT Q_DECL_IMPORT
#endif
#endif // TEST_GLOBAL_H

test.cpp:

#include "test.h"

Test::Test()
{
}

test.h:

#ifndef TEST_H
#define TEST_H
#include "test_global.h"
class TESTSHARED_EXPORT Test
{
public:
    Test();
};
#endif // TEST_H

test.pro:

#-------------------------------------------------
#
# Project created by QtCreator 2013-04-22T15:31:04
#
#-------------------------------------------------
QT       -= gui
TARGET = test
TEMPLATE = lib
DEFINES += TEST_LIBRARY
SOURCES += test.cpp
HEADERS += test.h
        test_global.h
unix:!symbian {
    maemo5 {
        target.path = /opt/usr/lib
    } else {
        target.path = /usr/lib
    }
    INSTALLS += target
}

编译输出:

13:49:12: Running steps for project loadTestLib...
13:49:12: Configuration unchanged, skipping qmake step.
13:49:12: Starting: "/usr/bin/make" -w
make: Entering directory `/home/bonart/Workspace/test/loadTestLib-build-Desktop_Qt_5_0_1_GCC_64bit-_______'
/home/bonart/Qt5.0.1/5.0.1/gcc_64/bin/qmake -spec linux-g++-64 CONFIG+=debug CONFIG+=declarative_debug CONFIG+=qml_debug -o Makefile ../loadTestLib/loadTestLib.pro
make: Leaving directory `/home/bonart/Workspace/test/loadTestLib-build-Desktop_Qt_5_0_1_GCC_64bit-_______'
make: Entering directory `/home/bonart/Workspace/test/loadTestLib-build-Desktop_Qt_5_0_1_GCC_64bit-_______'
g++ -m64 -Wl,-rpath,/home/bonart/Qt5.0.1/5.0.1/gcc_64 -Wl,-rpath,/home/bonart/Qt5.0.1/5.0.1/gcc_64/lib -o loadTestLib main.o   -L./libs -L../libs/-ltest -L/home/bonart/Qt5.0.1/5.0.1/gcc_64/lib -lQt5Core -lpthread 
main.o: In function `main':
/home/bonart/Workspace/test/loadTestLib-build-Desktop_Qt_5_0_1_GCC_64bit-_______/../loadTestLib/main.cpp:7: undefined reference to `Test::Test()'
make: Leaving directory `/home/bonart/Workspace/test/loadTestLib-build-Desktop_Qt_5_0_1_GCC_64bit-_______'
collect2: ld returned 1 exit status
make: *** [loadTestLib] Error 1
13:49:12: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project loadTestLib (kit: Desktop Qt 5.0.1 GCC 64bit)
When executing step 'Сборка'

$ nm -D for my library给我:

w _Jv_RegisterClasses
                 U _Unwind_Resume
                 U _Z17qt_message_output9QtMsgTypeRK18QMessageLogContextRK7QString
                 U _ZN10QArrayData10deallocateEPS_mm
                 U _ZN11QTextStreamD1Ev
                 U _ZN11QTextStreamlsERK7QString
                 U _ZN11QTextStreamlsEc
0000000000000bb0 T _ZN4TestC1Ev
0000000000000bb0 T _ZN4TestC2Ev
0000000000000d90 W _ZN6QDebugD1Ev
0000000000000d90 W _ZN6QDebugD2Ev
                 U _ZN7QString15fromUtf8_helperEPKci
                 U _ZNK14QMessageLogger5debugEv
                 U _ZTISt9bad_alloc
                 U _ZdlPv
0000000000202080 A __bss_start
                 U __cxa_begin_catch
                 U __cxa_end_catch
                 w __cxa_finalize
                 w __gmon_start__
                 U __gxx_personality_v0
0000000000202080 A _edata
0000000000202090 A _end
0000000000000ec8 T _fini
00000000000009e8 T _init

Answer 1

您的LIBS行在in loadTestLib。亲是错的。应该是

LIBS+=-L.. -ltest

或者你可以把它放在两行(也使用空格)，以清晰

LIBS += -L..
LIBS += -ltest

注意，这将链接到../libtest.so。通常在构建时链接不带版本后缀的文件，在运行时链接带版本号的文件。

Answer 2

除了Troubadour所说的，你应该告诉链接器在哪里可以找到这个库。您可以在.pro文件中设置QMAKE_LIBDIR，或者将包含库的目录添加到/etc/ld.so.conf并使用ldconfig命令。

Answer 3

在Windows的绝对路径库和它的名字与。dll为我工作。在Ubuntu中，它也以同样的方式成功编译，但是只有当你把它放到/usr/lib