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57 lines
1.5 KiB
57 lines
1.5 KiB
package com.example.myapplication.data
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import android.content.Context
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import androidx.room.Database
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import androidx.room.Room
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import androidx.room.RoomDatabase
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/**
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* 便签数据库类
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*
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* 使用 Room 持久化库管理 SQLite 数据库
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* 采用单例模式确保整个应用只有一个数据库实例
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*
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* @property noteDao 提供便签数据访问对象
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*/
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@Database(
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entities = [Note::class],
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version = 1,
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exportSchema = false
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)
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abstract class NoteDatabase : RoomDatabase() {
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/**
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* 获取便签数据访问对象
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*
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* @return NoteDao 实例，用于执行数据库操作
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*/
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abstract fun noteDao(): NoteDao
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companion object {
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@Volatile
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private var INSTANCE: NoteDatabase? = null
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/**
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* 获取数据库单例实例
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*
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* 使用双重检查锁定模式确保线程安全
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*
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* @param context 应用上下文
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* @return NoteDatabase 单例实例
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*/
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fun getDatabase(context: Context): NoteDatabase {
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return INSTANCE ?: synchronized(this) {
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val instance = Room.databaseBuilder(
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context.applicationContext,
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NoteDatabase::class.java,
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"note_database"
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)
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.fallbackToDestructiveMigration() // 数据库版本变化时销毁重建
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.build()
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INSTANCE = instance
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instance
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}
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}
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}
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}
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