QT5实现音乐播放器是十分简单的，因为内部已经封装好了 QMediaPlayer 和 QMediaPlaylist。通过QMediaPlaylist加入歌曲，形成歌曲列表，再把列表加入到QMediaPlayer 中去。然后直接通过QMediaPlayer 的函数来实现对音乐的基本操作。QMediaPlayer 还提供了一些信号，比如进度和音量，可以直接获取并做其他操作。

1. 创建播放器对象和加入播放列表。
   QMediaPlayer *player; //音乐播放器
   QMediaPlaylist *playList; //音乐播放列表
   playList=new QMediaPlaylist;
   playList->setPlaybackMode(QMediaPlaylist::Random);
   player=new QMediaPlayer;
   player->setPlaylist(playList);

• 添加本地音乐。
  connect(ui->pushButton_add, SIGNAL(clicked()), this, SLOT(slot_importLocalSongs()));
  void Body::slot_importLocalSongs()
  {
  QString initialName=QDir::homePath();
  QStringList pathList=QFileDialog::getOpenFileNames(this, tr("选择文件"), initialName, tr("*.mp3"));
  for(int i=0; i<pathList.size(); ++i) {
  QString path=QDir::toNativeSeparators(pathList.at(i));
  if(!path.isEmpty()) {
  playList->addMedia(QUrl::fromLocalFile(path));
  QString fileName=path.split("\").last();
  int rownum=ui->tableWidget_music->rowCount();
  ui->tableWidget_music->insertRow(rownum);
  ui->tableWidget_music->setItem(rownum, 0, new QTableWidgetItem(fileName.split(".").front()));
  }
  }
  }

• 播放或暂停音乐。
  connect(ui->pushButton_play, SIGNAL(clicked()), this, SLOT(slot_playOrPause()));
  void Body::slot_playOrPause()
  {
  if(ui->pushButton_play->text()==tr(">"))
  {
  player->play();
  ui->pushButton_play->setText(tr("||"));
  }
  else
  {
  player->pause();
  ui->pushButton_play->setText(tr(">"));
  }
  }

• 播放上一首。
  connect(ui->pushButton_pre, SIGNAL(clicked()), this, SLOT(slot_playPrev()));
  void Body::slot_playPrev()
  {
  int currentIndex = playList->currentIndex();
  if(--currentIndex<0)
  currentIndex = ui->tableWidget_music->rowCount() - 1;
  playList->setCurrentIndex(currentIndex);
  player->play();

       //高亮
       ui->tableWidget_music->selectRow(currentIndex);
       ui->tableWidget_music->setFocus(Qt::MouseFocusReason);
   }
  

• 播放下一首。
  connect(ui->pushButton_next, SIGNAL(clicked()), this, SLOT(slot_playNext()));
  void Body::slot_playNext()
  {
  int currentIndex=playList->currentIndex();
  if(++currentIndex==playList->mediaCount())
  currentIndex=0;
  playList->setCurrentIndex(currentIndex);
  player->play();

       //高亮
       ui->tableWidget_music->selectRow(currentIndex);
       ui->tableWidget_music->setFocus(Qt::MouseFocusReason);
   }
  

• 进度条设置
  connect(ui->slider_duration, SIGNAL(sliderMoved(int)), this, SLOT(slot_setPosition_duration(int)));
  void Body::slot_setPosition_duration(int position)
  {
  player->setPosition(position);
  }

• 音量设置
  connect(ui->slider_volume, SIGNAL(valueChanged(int)), this, SLOT(slot_setPosition_volume(int)));
  void Body::slot_setPosition_volume(int volume)
  {
  if(flag_slience) //如果是静音的
  {
  ui->pushButton_silence->setText("off"); //标识设为静音
  flag_slience = false; //标识设为非静音
  }
  player->setVolume(volume); //设置播放器的
  ui->slider_volume->setValue(volume);
  }