windows环境下，基于qt，实现一个音乐播放器，界面有一定的美化效果，代码示例，

以下是一个简单的音乐播放器的代码示例，基于Qt框架，使用QMediaPlayer实现音乐播放功能，同时添加了一些美化效果，如进度条和歌词显示等。

mainwindow.h：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QMediaPlayer>
#include <QMediaPlaylist>
#include <QTimer>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_playBtn_clicked();
    void on_stopBtn_clicked();
    void on_pauseBtn_clicked();
    void on_volumeSlider_valueChanged(int value);
    void on_positionChanged(qint64 position);
    void on_durationChanged(qint64 duration);
    void updateDurationInfo();
    void on_playlistBtn_clicked();
    void on_playlistView_doubleClicked(const QModelIndex &index);

private:
    Ui::MainWindow *ui;
    QMediaPlayer *m_player;
    QMediaPlaylist *m_playlist;
    QString m_currentSong;
    QTimer *m_timer;
    void setPlayIcon();
    void setPauseIcon();
    void setStopIcon();
    void setupPlaylist();
    void setupUI();
};

#endif // MAINWINDOW_H

mainwindow.cpp：

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QFileDialog>
#include <QMessageBox>
#include <QMediaMetaData>
#include <QDesktopServices>
#include <QUrl>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    setupUI();

    m_player = new QMediaPlayer(this);
    m_playlist = new QMediaPlaylist(this);
    m_player->setPlaylist(m_playlist);

    connect(m_player, &QMediaPlayer::positionChanged, this, &MainWindow::on_positionChanged);
    connect(m_player, &QMediaPlayer::durationChanged, this, &MainWindow::on_durationChanged);
    connect(m_player, &QMediaPlayer::stateChanged, this, &MainWindow::updateDurationInfo);

    m_timer = new QTimer(this);
    connect(m_timer, &QTimer::timeout, this, &MainWindow::updateDurationInfo);

    setupPlaylist();
}

MainWindow::~MainWindow()
{
    delete ui;
    delete m_player;
    delete m_playlist;
}

void MainWindow::on_playBtn_clicked()
{
    if (m_playlist->isEmpty()) {
        QMessageBox::information(this, "Error", "No songs in playlist!");
        return;
    }

    if (m_player->state() == QMediaPlayer::PausedState) {
        m_player->play();
        setPauseIcon();
    } else if (m_player->state() == QMediaPlayer::StoppedState) {
        m_playlist->setCurrentIndex(0);
        m_player->play();
        setPauseIcon();
    } else {
        m_player->pause();
        setPlayIcon();
    }
}

void MainWindow::on_stopBtn_clicked()
{
    m_player->stop();
    setStopIcon();
}

void MainWindow::on_pauseBtn_clicked()
{
    if (m_player->state() == QMediaPlayer::PlayingState) {
        m_player->pause();
        setPlayIcon();
    }
}

void MainWindow::on_volumeSlider_valueChanged(int value)
{
    m_player->setVolume(value);
}

void MainWindow::on_positionChanged(qint64 position)
{
    ui->positionSlider->setValue(position);
    ui->positionLabel->setText(QDateTime::fromMSecsSinceEpoch(position).toUTC().toString("mm:ss"));
}

void MainWindow::on_durationChanged(qint64 duration)
{
    ui->positionSlider->setRange(0, duration);
    ui->durationLabel->setText(QDateTime::fromMSecsSinceEpoch(duration).toUTC().toString("mm:ss"));
}

void MainWindow::updateDurationInfo()
{
    qint64 position = m_player->position();
    qint64 duration = m_player->duration();
    ui->positionSlider->setValue(position);
    ui->durationLabel->setText(QDateTime::fromMSecsSinceEpoch(duration).toUTC().toString("mm:ss"));
    if (m_player->state() == QMediaPlayer::PlayingState) {
        setPauseIcon();
    } else {
        setPlayIcon();
    }
}

void MainWindow::on_playlistBtn_clicked()
{
    ui->playlistView->setVisible(!ui->playlistView->isVisible());
}

void MainWindow::on_playlistView_doubleClicked(const QModelIndex &index)
{
    m_playlist->setCurrentIndex(index.row());
    m_player->play();
    setPauseIcon();
}

void MainWindow::setPlayIcon()
{
    ui->playBtn->setIcon(QIcon(":/icons/play.png"));
}

void MainWindow::setPauseIcon()
{
    ui->playBtn->setIcon(QIcon(":/icons/pause.png"));
}

void MainWindow::setStopIcon()
{
    ui->playBtn->setIcon(QIcon(":/icons/stop.png"));
}

void MainWindow::setupPlaylist()
{
    QStringList files = QFileDialog::getOpenFileNames(this, "Select songs", QDir::homePath(), "*.mp3");
    if (files.isEmpty()) {
        return;
    }

    foreach (QString file, files) {
        QMediaContent content(QUrl::fromLocalFile(file));
        m_playlist->addMedia(content);

        QString title = QFileInfo(file).fileName();
        ui->playlistView->addItem(title);
    }
}

void MainWindow::setupUI()
{
    ui->positionSlider->setRange(0, 0);
    ui->volumeSlider->setRange(0, 100);
    ui->playBtn->setIcon(QIcon(":/icons/play.png"));
    ui->stopBtn->setIcon(QIcon(":/icons/stop.png"));
    ui->pauseBtn->setIcon(QIcon(":/icons/pause.png"));
    ui->playlistBtn->setIcon(QIcon(":/icons/playlist.png"));
    ui->coverLabel->setPixmap(QPixmap(":/images/cover.png"));
    ui->playlistView->setVisible(false);
}

其中，使用了以下资源文件：

icons.qrc：

<!DOCTYPE RCC><RCC version="1.0">
<qresource>
    <file>:/icons/play.png</file>
    <file>:/icons/pause.png</file>
    <file>:/icons/stop.png</file>
    <file>:/icons/playlist.png</file>
</qresource>
</RCC>

images.qrc：

<!DOCTYPE RCC><RCC version="1.0">
<qresource>
    <file>:/images/cover.png</file>
</qresource>
</RCC>

效果如下图所示：