HarmonyOS NEXT 中级开发笔记：基于HarmonyOS Design的音乐应用数据库实践-优快云博客

今天在适配"舞动音乐"应用到HarmonyOS NEXT时，重点解决了数据库模块的设计问题。HarmonyOS Design强调简洁高效的数据管理，这对音乐类应用尤为重要。以下是核心实现思路：

1. 数据库模型设计
遵循HarmonyOS Design的"以用户为中心"原则，设计了三个主要实体表：

typescript

// 音乐表
@Entity
export class Music {
  @PrimaryKey()
  id: number;
  
  @ColumnInfo(name: "title")
  title: string;
  
  @ColumnInfo(name: "artist")
  artist: string;
  
  @ColumnInfo(name: "duration")
  duration: number; // 毫秒
}

// 播放列表表
@Entity
export class Playlist {
  @PrimaryKey()
  id: number;
  
  @ColumnInfo(name: "name")
  name: string;
}

// 关联表（多对多关系）
@Entity
export class PlaylistMusicMap {
  @PrimaryKey()
  id: number;
  
  @ColumnInfo(name: "playlist_id")
  playlistId: number;
  
  @ColumnInfo(name: "music_id")
  musicId: number;
}

2. 数据库操作封装
采用HarmonyOS的RDB模块，兼容API12接口：

typescript

import relationalStore from '@ohos.data.relationalStore';

const STORE_CONFIG = {
  name: "MusicDB.db",
  securityLevel: relationalStore.SecurityLevel.S1
};

async function initDatabase(): Promise<relationalStore.RdbStore> {
  const rdbStore = await relationalStore.getRdbStore(this.context, STORE_CONFIG);
  
  // 创建表（实际开发需考虑版本迁移）
  await rdbStore.executeSql(`
    CREATE TABLE IF NOT EXISTS music (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      title TEXT NOT NULL,
      artist TEXT,
      duration INTEGER
    )`);
  
  return rdbStore;
}

3. 复杂查询示例
实现HarmonyOS Design推荐的"快速加载"体验：

typescript

// 获取播放列表详情（包含关联歌曲）
async function getPlaylistDetail(rdbStore: relationalStore.RdbStore, playlistId: number): Promise<PlaylistWithMusics> {
  const playlist = await rdbStore.query(
    predicates: relationalStore.RdbPredicates("playlist").equalTo("id", playlistId)
  );
  
  const musics = await rdbStore.query(
    predicates: relationalStore.RdbPredicates("music")
      .join("playlist_music_map", "music.id = playlist_music_map.music_id")
      .equalTo("playlist_music_map.playlist_id", playlistId)
  );
  
  return { ...playlist, musics };
}

遇到的问题：