例如我创建了一个Music的实体,但是我想用它创建更多的数据表,
例如: "Like" 一个表 ,"PlayHistory"一个表,"LocalMusic"又一个表,都是同时用"Music"的实体类应当怎么写?
以下是我的代码
class App :Application() {
private var boxStore: BoxStore? = null
override fun onCreate() {
super.onCreate()
//......
initDataBase()
//......
}
private fun initDataBase(){
boxStore = MyObjectBox.builder()
.androidContext(this)
.build()
boxStore?.startObjectBrowser(8090)
}
fun getMusicBoxStore(): Box<Music>? {
return boxStore?.boxFor(Music::class.java)
}
fun getMusicCacheBoxStore(): Box<MusicCache>? {
return boxStore?.boxFor(MusicCache::class.java)
}
}
给创建一个独立的实体类,然后用同一个BoxStore实例给它们对应的box
class MusicLike : Entity() {
var musicId: Long = 0
//...
}
class MusicPlayHistory : Entity() {
var musicId: Long = 0
//...
}
class LocalMusic : Entity() {
var musicId: Long = 0
//...
}
fun getMusicLikeBoxStore(): Box<MusicLike>? {
return boxStore?.boxFor(MusicLike::class.java)
}
fun getMusicPlayHistoryBoxStore(): Box<MusicPlayHistory>? {
return boxStore?.boxFor(MusicPlayHistory::class.java)
}
fun getLocalMusicBoxStore(): Box<LocalMusic>? {
return boxStore?.boxFor(LocalMusic::class.java)
}
每个表都有自己的实体类,由同一个BoxStore实例与数据库进行交互。
注意: 可以使用在实体文件中定义多个实体类,各自可以声明不同的表名。 具体步骤:
1、在实体文件中定义多个实体类(需要实现自定义表名),如:
@Entity(name="t_music_like") public class MusicLike extends Music { @Id public long id; public int likes; }
@Entity(name="t_music_playHistory") public class MusicPlayHistory extends Music { @Id public long id; public int playCount; }
@Entity (name="t_music_localMusic") public class LocalMusic extends Music { @Id public long id; public int downloadCount; }
2、在app中定义相应box实例:
Box musicLikeBox = store.boxFor(MusicLike.class); Box musicPlayHistoryBox= store.boxFor(MusicPlayHistory.class); Box localMusicBox = store.boxFor(LocalMusic.class);
3、最后,你就可以使用box实例各自进行相应的操作了,比如:
musicLikeBox.put(musicLike); musicPlayHistoryBox.put(musicPlayHistory); localMusicBox.put(localMusic);
您需要创建"Like"、"PlayHistory"和"LocalMusic"的实体类,并在这些类中继承"Music"类。例如:
@Entity
class Like : Music() {
// additional fields and methods for "Like"
}
@Entity
class PlayHistory : Music() {
// additional fields and methods for "PlayHistory"
}
@Entity
class LocalMusic : Music() {
// additional fields and methods for "LocalMusic"
}
接着,您可以分别在App类中添加方法来获取"Like"、"PlayHistory"和"LocalMusic"的Box对象:
fun getLikeBoxStore(): Box<Like>? {
return boxStore?.boxFor(Like::class.java)
}
fun getPlayHistoryBoxStore(): Box<PlayHistory>? {
return boxStore?.boxFor(PlayHistory::class.java)
}
fun getLocalMusicBoxStore(): Box<LocalMusic>? {
return boxStore?.boxFor(LocalMusic::class.java)
}
hello,world
该回答引用ChatGPT
可以在initDataBase()函数中创建新的Box
private fun initDataBase(){
boxStore = MyObjectBox.builder()
.androidContext(this)
.build()
boxStore?.startObjectBrowser(8090)
getLikeBoxStore()
getPlayHistoryBoxStore()
getLocalMusicBoxStore()
}
fun getMusicBoxStore(): Box<Music>? {
return boxStore?.boxFor(Music::class.java)
}
fun getLikeBoxStore(): Box<Like>? {
return boxStore?.boxFor(Like::class.java)
}
fun getPlayHistoryBoxStore(): Box<PlayHistory>? {
return boxStore?.boxFor(PlayHistory::class.java)
}
fun getLocalMusicBoxStore(): Box<LocalMusic>? {
return boxStore?.boxFor(LocalMusic::class.java)
}
创建不同的实体类,PlayHistory、MusicLike、LocalMusic,然后传入不同的实体类的class即可
fun getMusicLikeBoxStore(): Box<MusicLike>? {
return boxStore?.boxFor(MusicLike::class.java)
}
fun getMusicPlayHistoryBoxStore(): Box<MusicPlayHistory>? {
return boxStore?.boxFor(PlayHistory::class.java)
}
fun getLocalMusicBoxStore(): Box<LocalMusic>? {
return boxStore?.boxFor(LocalMusic::class.java)
}
内部类嵌套即可完成。
这里你需要使用BoxStore.builder()函数来构建实体类,boxStore.boxFor()函数可以用来创建实体类对应的数据表。例如,你想创建一个Like实体表,则可以这样写:boxStore?.boxFor(Like::class.java)。同理,你也可以使用这个函数创建PlayHistory、LocalMusic实体表,即:boxStore?.boxFor(PlayHistory::class.java),boxStore?.boxFor(LocalMusic::class.java)。
该回答引用ChatGPT
_请参考下面的解决方案,如果有帮助,还请点击 “采纳” _
您可以在代码中通过复制并修改getMusicCacheBoxStore方法,来创建其他表。
例如:
fun getLikeBoxStore(): Box<Like>? {
return boxStore?.boxFor(Like::class.java)
}
fun getPlayHistoryBoxStore(): Box<PlayHistory>? {
return boxStore?.boxFor(PlayHistory::class.java)
}
fun getLocalMusicBoxStore(): Box<LocalMusic>? {
return boxStore?.boxFor(LocalMusic::class.java)
}
每个方法都返回一个特定的表。
需要注意的是,您还需要创建Like,PlayHistory和LocalMusic类,以在您的数据库中创建这些表。