音乐播放器应用程序的低级设计

设计音乐播放器应用程序需要仔细规划和构建组件，以确保无缝、高效的用户体验。

音乐播放器的关键要求

系统设计概述

音乐播放器应用程序可以分为以下几个组件：

让我们看看每个组件的底层设计和实现。

1. 歌曲课

“Song”类代表带有元数据的单个音乐曲目。

public class Song {
    private String id;
    private String title;
    private String artist;
    private String album;
    private double duration; // in seconds

    public Song(String id, String title, String artist, String album, double duration) {
        this.id = id;
        this.title = title;
        this.artist = artist;
        this.album = album;
        this.duration = duration;
    }

    // Getters and setters
    public String getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public String getArtist() {
        return artist;
    }

    public String getAlbum() {
        return album;
    }

    public double getDuration() {
        return duration;
    }
}

2. 播放列表类

`Playlist` 类管理歌曲集合。它允许添加、删除和获取歌曲。

import java.util.ArrayList;
import java.util.List;

public class Playlist {
    private String name;
    private List songs;

    public Playlist(String name) {
        this.name = name;
        this.songs = new ArrayList<>();
    }

    public void addSong(Song song) {
        songs.add(song);
    }

    public void removeSong(Song song) {
        songs.remove(song);
    }

    public List getSongs() {
        return songs;
    }

    public String getName() {
        return name;
    }
}

3. MusicPlayer 类

`MusicPlayer` 类处理播放、暂停、停止和音量控制等播放功能。

public class MusicPlayer {
    private Song currentSong;
    private boolean isPlaying;

    public void play(Song song) {
        this.currentSong = song;
        this.isPlaying = true;
        System.out.println("Playing: " + song.getTitle() + " by " + song.getArtist());
    }

    public void pause() {
        if (isPlaying) {
            isPlaying = false;
            System.out.println("Paused: " + currentSong.getTitle());
        } else {
            System.out.println("No song is currently playing.");
        }
    }

    public void stop() {
        if (currentSong != null) {
            System.out.println("Stopped: " + currentSong.getTitle());
            currentSong = null;
            isPlaying = false;
        } else {
            System.out.println("No song is currently playing.");
        }
    }

    public void resume() {
        if (currentSong != null && !isPlaying) {
            isPlaying = true;
            System.out.println("Resumed: " + currentSong.getTitle());
        } else {
            System.out.println("No song to resume.");
        }
    }
}

4. SearchService 类

`SearchService` 类允许用户按标题、艺术家或专辑搜索歌曲。

import java.util.ArrayList;
import java.util.List;

public class SearchService {
    private List songs;

    public SearchService(List songs) {
        this.songs = songs;
    }

    public List searchByTitle(String title) {
        List results = new ArrayList<>();
        for (Song song : songs) {
            if (song.getTitle().equalsIgnoreCase(title)) {
                results.add(song);
            }
        }
        return results;
    }

    public List searchByArtist(String artist) {
        List results = new ArrayList<>();
        for (Song song : songs) {
            if (song.getArtist().equalsIgnoreCase(artist)) {
                results.add(song);
            }
        }
        return results;
    }

    public List searchByAlbum(String album) {
        List results = new ArrayList<>();
        for (Song song : songs) {
            if (song.getAlbum().equalsIgnoreCase(album)) {
                results.add(song);
            }
        }
        return results;
    }
}

5. StorageService 类

`StorageService` 类模拟从本地存储读取歌曲。

import java.util.ArrayList;
import java.util.List;

public class StorageService {
    public static List loadSongs() {
        List songs = new ArrayList<>();
        songs.add(new Song("1", "Shape of You", "Ed Sheeran", "Divide", 240));
        songs.add(new Song("2", "Blinding Lights", "The Weeknd", "After Hours", 200));
        songs.add(new Song("3", "Levitating", "Dua Lipa", "Future Nostalgia", 220));
        return songs;
    }
}

示例用法

import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Load songs from storage
        List songs = StorageService.loadSongs();

        // Search service
        SearchService searchService = new SearchService(songs);
        List results = searchService.searchByArtist("Ed Sheeran");
        System.out.println("Songs by Ed Sheeran:");
        for (Song song : results) {
            System.out.println(song.getTitle());
        }

        // Play a song
        MusicPlayer musicPlayer = new MusicPlayer();
        musicPlayer.play(songs.get(0));
        musicPlayer.pause();
        musicPlayer.resume();
        musicPlayer.stop();

        // Create a playlist
        Playlist playlist = new Playlist("Favorites");
        playlist.addSong(songs.get(1));
        playlist.addSong(songs.get(2));
        System.out.println("Playlist: " + playlist.getName());
        for (Song song : playlist.getSongs()) {
            System.out.println(song.getTitle());
        }
    }
}

关键要点