TagLib：无法打开文件

Question

我正在尝试编写一个简单的程序来了解 TagLib (http://developer.kde.org/~wheeler/taglib.html) 的工作原理。该程序可以很好地与代码中的 cmets 配合使用。但是当我更改代码时，我得到了这些我无法解决的错误。 这是代码

#include<iostream>
#include<QString>
//#include "Helper.h"
#include "../../player/Util.h"
#include <taglib/tag.h>
#include <taglib/taglib.h>
#include <taglib/fileref.h>
#include <QString>


#include <boost/filesystem.hpp>

using std::string;
struct MetaData{

    string filepath, artist, album, title;
    signed int year, track_num, length_ms, bitrate;
};

//MetaData getMetaDataOfFile(QString file)
MetaData getMetaDataOfFile(string file)
{
    MetaData md;
    //TagLib::FileRef f(TagLib::FileName(file.toUtf8())); 
    const char * filename = file.c_str();
    std::cout<< filename;
    TagLib::FileRef f(TagLib::FileName(filename)); 

    //md.filepath = file.toStdString();
    md.filepath = file;

    //boost::filesystem::path filePath(file.toStdString());
    boost::filesystem::path filePath(file);
    md.title = filePath.stem().string();

    if(f.isNull()) return md;
    if(!f.tag()) return md;
    if(f.tag()->isEmpty()) return md;

    string artist = f.tag()->artist().to8Bit(true);
    string album = f.tag()->album().to8Bit(true);
    string title = f.tag()->title().to8Bit(true);
    uint year = f.tag()->year();
    uint track = f.tag()->track();
    int bitrate = f.audioProperties()->bitrate() * 1000;
    int length = f.audioProperties()->length();

    md.album = cnvrtString2FirstUpper(album);
    md.artist = cnvrtString2FirstUpper(artist);
    md.title = cnvrtString2FirstUpper(title);
    //md.filepath = file.toStdString();
    md.filepath = file;
    md.length_ms = length * 1000;
    md.year = year;
    md.track_num = track;
    md.bitrate = bitrate;

    if(md.title.length()==0)
    {

    //boost::filesystem::path filePath(file.toStdString());
    boost::filesystem::path filePath(file);
    md.title = filePath.stem().string();
    }

    return md;
}






int main()
{
    using namespace std;



    //QString file("/home/vickey/Downloads/song1.mp3");
    string file("/home/vickey/Downloads/song1.mp3");
    MetaData md = getMetaDataOfFile(file);

    return 0;

}

编译时出现此错误

 g++ getmd.cpp -o getmd -I /usr/include/qt4/ -I /usr/include/qt4/QtCore/ -ltag -lboost_system -lboost_filesystem -lQtCore -g
getmd.cpp: In function ‘MetaData getMetaDataOfFile(std::string)’:
getmd.cpp:36:10: error: request for member ‘isNull’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:37:11: error: request for member ‘tag’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:38:10: error: request for member ‘tag’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:40:23: error: request for member ‘tag’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:41:22: error: request for member ‘tag’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:42:22: error: request for member ‘tag’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:43:19: error: request for member ‘tag’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
g    etmd.cpp:44:20: error: request for member ‘tag’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:45:21: error: request for member ‘audioProperties’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’
getmd.cpp:46:20: error: request for member ‘audioProperties’ in ‘f’, which is of non-class type ‘TagLib::FileRef(TagLib::FileName) {aka TagLib::FileRef(const char*)}’

Answer 1

两个版本（已注释和未注释）都是错误的。 Unix 上的 TagLib 需要 const char * 文件名。从QString 获得一个的最佳方式是使用QFile::encodeName()。所以你应该有这样的东西：

TagLib::FileRef f(QFile::encodeName(file).constData());