报错： 使用QDomDocument自定义xml文件的读写类，构建不通过，

        .cpp:5: undefined reference to `_imp___ZN12QDomDocumentC1Ev'

        .cpp:5: undefined reference to `_imp___ZN12QDomDocumentC1Ev'

        .cpp:11: undefined reference to `_imp___ZN25QDomProcessingInstructionC1Ev'

        .cpp:12: undefined reference to `_imp___ZN12QDomDocument27createProcessingInstructionERK7QStringS2_'

        .cpp:12: undefined reference to `_imp___ZN25QDomProcessingInstructionaSERKS_'

        .cpp:13: undefined reference to `_imp___ZN8QDomNode11appendChildERKS_'

        .cpp:13: undefined reference to `_imp___ZN8QDomNodeD1Ev'

        .cpp:15: undefined reference to `_imp___ZN12QDomDocument13createElementERK7QString'

        .cpp:16: undefined reference to `_imp___ZN8QDomNode11appendChildERKS_'

        .cpp:16: undefined reference to `_imp___ZN8QDomNodeD1Ev'

        .cpp:23: undefined reference to `_imp___ZNK8QDomNode6isNullEv'

        .cpp:25: undefined reference to `_imp___ZN11QDomElementC1ERKS_'

        添加各种头文件，即使将自定义类继承子QObject仍编译不通过，修改方法为：

        打开.pro工程文件，将：

                QT       += core gui

        修改为：

                QT       += core gui \

                                        xml