diff --git a/.claude/settings.local.json b/.claude/settings.local.json
new file mode 100644
index 0000000..f50d242
--- /dev/null
+++ b/.claude/settings.local.json
@@ -0,0 +1,8 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(./gradlew:*)"
+    ],
+    "deny": []
+  }
+}
\ No newline at end of file
diff --git a/.idea/AndroidProjectSystem.xml b/.idea/AndroidProjectSystem.xml
new file mode 100644
index 0000000..4a53bee
--- /dev/null
+++ b/.idea/AndroidProjectSystem.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="AndroidProjectSystem">
+    <option name="providerId" value="com.android.tools.idea.GradleProjectSystem" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/inspectionProfiles/Project_Default.xml b/.idea/inspectionProfiles/Project_Default.xml
index cde3e19..763e424 100644
--- a/.idea/inspectionProfiles/Project_Default.xml
+++ b/.idea/inspectionProfiles/Project_Default.xml
@@ -49,6 +49,9 @@
       <option name="composableFile" value="true" />
       <option name="previewFile" value="true" />
     </inspection_tool>
+    <inspection_tool class="PreviewParameterProviderOnFirstParameter" enabled="true" level="ERROR" enabled_by_default="true">
+      <option name="composableFile" value="true" />
+    </inspection_tool>
     <inspection_tool class="PreviewPickerAnnotation" enabled="true" level="ERROR" enabled_by_default="true">
       <option name="composableFile" value="true" />
       <option name="previewFile" value="true" />
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..f4d2304
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,117 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## 项目概述
+
+轻记账是一个使用 Kotlin 和 Jetpack Compose 开发的 Android 记账应用，采用 MVVM 架构。项目强调隐私保护，完全离线运行。
+
+## 常用命令
+
+### 构建和运行
+```bash
+./gradlew build              # 构建项目
+./gradlew assembleDebug      # 构建调试 APK
+./gradlew assembleRelease    # 构建发布 APK
+./gradlew installDebug       # 安装调试版本到设备
+./gradlew clean             # 清理构建产物
+```
+
+### 测试相关
+```bash
+./gradlew test              # 运行单元测试
+./gradlew connectedAndroidTest  # 运行设备测试
+```
+
+## 架构概览
+
+### MVVM 架构分层
+- **Model 层**: Room 数据库实体 (`model/` 目录下的 BookkeepingRecord, Category, Member, Settings)
+- **Data 层**: DAO 接口和 Repository 模式实现数据访问
+- **ViewModel 层**: 每个功能模块独立的 ViewModel (HomeViewModel, AnalysisViewModel 等)
+- **View 层**: Jetpack Compose UI，包含 screens、components 和 dialogs
+
+### 核心数据流
+1. UI 层通过 ViewModel 发起数据请求
+2. ViewModel 调用 Repository 获取数据
+3. Repository 通过 DAO 访问 Room 数据库
+4. 数据通过 Flow/StateFlow 响应式传递回 UI
+
+### 数据库架构
+- **主数据库**: BookkeepingDatabase (当前版本 5)
+- **核心表**: bookkeeping_records, categories, members, settings
+- **关键关系**: records 通过 memberId 关联 members 表
+- **迁移策略**: 使用 Room 的 Migration 机制处理版本升级
+
+### 导航架构
+使用 Jetpack Navigation Compose，主要页面：
+- HomeScreen: 主页记账列表
+- AnalysisScreen: 数据分析图表
+- AddRecordScreen: 添加/编辑记录
+- CategoryManagementScreen: 分类管理
+- MemberManagementScreen: 成员管理
+- SettingsScreen: 设置页面
+
+## 关键技术决策
+
+### UI 框架
+- 完全使用 Jetpack Compose 构建 UI
+- Material 3 设计系统，支持深色/浅色主题
+- 自定义主题色功能通过 ColorThemeDialog 实现
+
+### 数据可视化
+- 使用 MPAndroidChart 实现图表功能
+- ChartManager 统一管理图表样式和行为
+- 支持饼图和折线图两种展示方式
+
+### 文件导入导出
+- Apache POI 处理 Excel 文件
+- OpenCSV 处理 CSV 文件
+- FileUtils 提供统一的文件操作接口
+
+### 图标系统
+- 所有图标使用 Material Icons 和自定义矢量图标
+- CategoryIcon 和 MemberIcon 枚举管理图标映射
+- 支持动态图标选择和预览
+
+## 开发注意事项
+
+### 分支策略
+- master: 稳定主分支
+- develop: 开发分支
+- feature/*: 功能开发
+- release/*: 版本发布
+- hotfix/*: 紧急修复
+
+### 提交规范
+使用约定式提交: `<type>: <description>`
+- feat: 新功能
+- fix: 修复 bug
+- docs: 文档更新
+- style: 代码格式
+- refactor: 代码重构
+- perf: 性能优化
+- test: 测试相关
+- build: 构建相关
+
+### 重要功能模块
+
+#### 月度记账开始日期 (Settings 中的 monthStartDay)
+- 支持自定义每月记账的开始日期 (1-31)
+- 影响月度统计和分析的日期范围计算
+- 默认值为 1 (每月 1 日开始)
+
+#### 加密功能 (EncryptionUtils)
+- 预留的备份加密功能接口
+- 使用 AES 加密算法
+- 目前尚未集成到备份功能中
+
+#### 默认数据初始化
+- 首次启动时自动创建默认分类
+- 包含常用的收入和支出分类
+- 可通过 insertDefaultCategories() 查看默认分类列表
+
+### 性能考虑
+- 使用 Room 的 Flow 实现数据的响应式更新
+- 图表数据计算在 ViewModel 中异步处理
+- 大量数据导入时使用批量插入优化性能
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/data/BookkeepingDatabase.kt b/app/src/main/java/com/yovinchen/bookkeeping/data/BookkeepingDatabase.kt
index 3fd3ccc..67093cb 100644
--- a/app/src/main/java/com/yovinchen/bookkeeping/data/BookkeepingDatabase.kt
+++ b/app/src/main/java/com/yovinchen/bookkeeping/data/BookkeepingDatabase.kt
@@ -10,17 +10,19 @@ import androidx.room.migration.Migration
 import androidx.sqlite.db.SupportSQLiteDatabase
 import com.yovinchen.bookkeeping.R
 import com.yovinchen.bookkeeping.model.BookkeepingRecord
+import com.yovinchen.bookkeeping.model.Budget
 import com.yovinchen.bookkeeping.model.Category
 import com.yovinchen.bookkeeping.model.Converters
 import com.yovinchen.bookkeeping.model.Member
+import com.yovinchen.bookkeeping.model.Settings
 import com.yovinchen.bookkeeping.model.TransactionType
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 
 @Database(
-    entities = [BookkeepingRecord::class, Category::class, Member::class],
-    version = 4,
+    entities = [BookkeepingRecord::class, Category::class, Member::class, Settings::class, Budget::class],
+    version = 6,
     exportSchema = false
 )
 @TypeConverters(Converters::class)
@@ -28,6 +30,8 @@ abstract class BookkeepingDatabase : RoomDatabase() {
     abstract fun bookkeepingDao(): BookkeepingDao
     abstract fun categoryDao(): CategoryDao
     abstract fun memberDao(): MemberDao
+    abstract fun settingsDao(): SettingsDao
+    abstract fun budgetDao(): BudgetDao
 
     companion object {
         private const val TAG = "BookkeepingDatabase"
@@ -124,6 +128,52 @@ abstract class BookkeepingDatabase : RoomDatabase() {
             }
         }
 
+        private val MIGRATION_4_5 = object : Migration(4, 5) {
+            override fun migrate(db: SupportSQLiteDatabase) {
+                // 创建设置表
+                db.execSQL("""
+                    CREATE TABLE IF NOT EXISTS settings (
+                        id INTEGER PRIMARY KEY NOT NULL DEFAULT 1,
+                        monthStartDay INTEGER NOT NULL DEFAULT 1,
+                        themeMode TEXT NOT NULL DEFAULT 'FOLLOW_SYSTEM',
+                        autoBackupEnabled INTEGER NOT NULL DEFAULT 0,
+                        autoBackupInterval INTEGER NOT NULL DEFAULT 7,
+                        lastBackupTime INTEGER NOT NULL DEFAULT 0
+                    )
+                """)
+                
+                // 插入默认设置
+                db.execSQL("""
+                    INSERT OR IGNORE INTO settings (id, monthStartDay, themeMode, autoBackupEnabled, autoBackupInterval, lastBackupTime)
+                    VALUES (1, 1, 'FOLLOW_SYSTEM', 0, 7, 0)
+                """)
+            }
+        }
+        
+        private val MIGRATION_5_6 = object : Migration(5, 6) {
+            override fun migrate(db: SupportSQLiteDatabase) {
+                // 创建预算表
+                db.execSQL("""
+                    CREATE TABLE IF NOT EXISTS budgets (
+                        id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
+                        type TEXT NOT NULL,
+                        categoryName TEXT,
+                        memberId INTEGER,
+                        amount REAL NOT NULL,
+                        startDate INTEGER NOT NULL,
+                        endDate INTEGER NOT NULL,
+                        isEnabled INTEGER NOT NULL DEFAULT 1,
+                        alertThreshold REAL NOT NULL DEFAULT 0.8,
+                        createdAt INTEGER NOT NULL,
+                        updatedAt INTEGER NOT NULL
+                    )
+                """)
+                
+                // 在 settings 表中添加 encryptBackup 列
+                db.execSQL("ALTER TABLE settings ADD COLUMN encryptBackup INTEGER NOT NULL DEFAULT 1")
+            }
+        }
+
         @Volatile
         private var INSTANCE: BookkeepingDatabase? = null
 
@@ -134,7 +184,7 @@ abstract class BookkeepingDatabase : RoomDatabase() {
                     BookkeepingDatabase::class.java,
                     "bookkeeping_database"
                 )
-                    .addMigrations(MIGRATION_1_2, MIGRATION_2_3, MIGRATION_3_4)
+                    .addMigrations(MIGRATION_1_2, MIGRATION_2_3, MIGRATION_3_4, MIGRATION_4_5, MIGRATION_5_6)
                     .addCallback(object : Callback() {
                         override fun onCreate(db: SupportSQLiteDatabase) {
                             super.onCreate(db)
@@ -143,6 +193,11 @@ abstract class BookkeepingDatabase : RoomDatabase() {
                                 try {
                                     val database = getDatabase(context)
                                     
+                                    // 初始化默认设置
+                                    database.settingsDao().apply {
+                                        updateSettings(Settings())
+                                    }
+                                    
                                     // 初始化默认成员
                                     database.memberDao().apply {
                                         if (getMemberCount() == 0) {
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/data/BudgetDao.kt b/app/src/main/java/com/yovinchen/bookkeeping/data/BudgetDao.kt
new file mode 100644
index 0000000..6e80750
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/data/BudgetDao.kt
@@ -0,0 +1,105 @@
+package com.yovinchen.bookkeeping.data
+
+import androidx.room.*
+import com.yovinchen.bookkeeping.model.Budget
+import com.yovinchen.bookkeeping.model.BudgetType
+import kotlinx.coroutines.flow.Flow
+import java.util.Date
+
+/**
+ * 预算数据访问对象
+ * 提供预算相关的数据库操作接口
+ */
+@Dao
+interface BudgetDao {
+    
+    /**
+     * 插入新预算
+     */
+    @Insert
+    suspend fun insertBudget(budget: Budget): Long
+    
+    /**
+     * 更新预算
+     */
+    @Update
+    suspend fun updateBudget(budget: Budget)
+    
+    /**
+     * 删除预算
+     */
+    @Delete
+    suspend fun deleteBudget(budget: Budget)
+    
+    /**
+     * 根据ID获取预算
+     */
+    @Query("SELECT * FROM budgets WHERE id = :budgetId")
+    suspend fun getBudgetById(budgetId: Int): Budget?
+    
+    /**
+     * 获取所有启用的预算
+     */
+    @Query("SELECT * FROM budgets WHERE isEnabled = 1 ORDER BY type, amount DESC")
+    fun getAllEnabledBudgets(): Flow<List<Budget>>
+    
+    /**
+     * 获取所有预算（包括禁用的）
+     */
+    @Query("SELECT * FROM budgets ORDER BY type, amount DESC")
+    fun getAllBudgets(): Flow<List<Budget>>
+    
+    /**
+     * 根据类型获取预算
+     */
+    @Query("SELECT * FROM budgets WHERE type = :type AND isEnabled = 1")
+    fun getBudgetsByType(type: BudgetType): Flow<List<Budget>>
+    
+    /**
+     * 获取总预算
+     */
+    @Query("SELECT * FROM budgets WHERE type = 'TOTAL' AND isEnabled = 1 AND :date BETWEEN startDate AND endDate LIMIT 1")
+    suspend fun getTotalBudget(date: Date): Budget?
+    
+    /**
+     * 获取指定分类的预算
+     */
+    @Query("SELECT * FROM budgets WHERE type = 'CATEGORY' AND categoryName = :categoryName AND isEnabled = 1 AND :date BETWEEN startDate AND endDate LIMIT 1")
+    suspend fun getCategoryBudget(categoryName: String, date: Date): Budget?
+    
+    /**
+     * 获取指定成员的预算
+     */
+    @Query("SELECT * FROM budgets WHERE type = 'MEMBER' AND memberId = :memberId AND isEnabled = 1 AND :date BETWEEN startDate AND endDate LIMIT 1")
+    suspend fun getMemberBudget(memberId: Int, date: Date): Budget?
+    
+    /**
+     * 获取当前有效的所有预算
+     */
+    @Query("SELECT * FROM budgets WHERE isEnabled = 1 AND :date BETWEEN startDate AND endDate ORDER BY type, amount DESC")
+    fun getActiveBudgets(date: Date): Flow<List<Budget>>
+    
+    /**
+     * 更新预算的启用状态
+     */
+    @Query("UPDATE budgets SET isEnabled = :enabled, updatedAt = :updatedAt WHERE id = :budgetId")
+    suspend fun updateBudgetEnabled(budgetId: Int, enabled: Boolean, updatedAt: Date = Date())
+    
+    /**
+     * 删除所有过期的预算（可选）
+     */
+    @Query("DELETE FROM budgets WHERE endDate < :date AND isEnabled = 0")
+    suspend fun deleteExpiredBudgets(date: Date)
+    
+    /**
+     * 获取指定日期范围内的分类预算
+     */
+    @Query("SELECT * FROM budgets WHERE type = 'CATEGORY' AND isEnabled = 1 AND :date BETWEEN startDate AND endDate")
+    fun getCategoryBudgetsForDate(date: Date): Flow<List<Budget>>
+    
+    /**
+     * 获取指定日期范围内的成员预算
+     */
+    @Query("SELECT * FROM budgets WHERE type = 'MEMBER' AND isEnabled = 1 AND :date BETWEEN startDate AND endDate")
+    fun getMemberBudgetsForDate(date: Date): Flow<List<Budget>>
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/data/BudgetRepository.kt b/app/src/main/java/com/yovinchen/bookkeeping/data/BudgetRepository.kt
new file mode 100644
index 0000000..8918790
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/data/BudgetRepository.kt
@@ -0,0 +1,215 @@
+package com.yovinchen.bookkeeping.data
+
+import com.yovinchen.bookkeeping.model.*
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.map
+import java.util.Date
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * 预算仓库类
+ * 提供预算相关的业务逻辑和数据访问
+ */
+class BudgetRepository(
+    private val budgetDao: BudgetDao,
+    private val bookkeepingDao: BookkeepingDao,
+    private val memberDao: MemberDao
+) {
+    
+    /**
+     * 创建新预算
+     */
+    suspend fun createBudget(budget: Budget): Long {
+        return budgetDao.insertBudget(budget)
+    }
+    
+    /**
+     * 更新预算
+     */
+    suspend fun updateBudget(budget: Budget) {
+        budgetDao.updateBudget(budget.copy(updatedAt = Date()))
+    }
+    
+    /**
+     * 删除预算
+     */
+    suspend fun deleteBudget(budget: Budget) {
+        budgetDao.deleteBudget(budget)
+    }
+    
+    /**
+     * 获取所有预算
+     */
+    fun getAllBudgets(): Flow<List<Budget>> {
+        return budgetDao.getAllBudgets()
+    }
+    
+    /**
+     * 获取所有启用的预算
+     */
+    fun getAllEnabledBudgets(): Flow<List<Budget>> {
+        return budgetDao.getAllEnabledBudgets()
+    }
+    
+    /**
+     * 获取当前有效的预算状态
+     */
+    fun getActiveBudgetStatuses(date: Date = Date()): Flow<List<BudgetStatus>> {
+        return combine(
+            budgetDao.getActiveBudgets(date),
+            bookkeepingDao.getAllRecords(),
+            memberDao.getAllMembers()
+        ) { budgets, records, members ->
+            budgets.map { budget ->
+                val spent = calculateSpent(budget, records, members, date)
+                val remaining = budget.amount - spent
+                val percentage = if (budget.amount > 0) spent / budget.amount else 0.0
+                
+                BudgetStatus(
+                    budget = budget,
+                    spent = spent,
+                    remaining = remaining,
+                    percentage = percentage,
+                    isOverBudget = spent > budget.amount,
+                    isNearLimit = percentage >= budget.alertThreshold
+                )
+            }
+        }
+    }
+    
+    /**
+     * 计算预算已花费金额
+     */
+    private fun calculateSpent(
+        budget: Budget,
+        records: List<BookkeepingRecord>,
+        members: List<Member>,
+        currentDate: Date
+    ): Double {
+        // 只计算支出类型的记录
+        val expenseRecords = records.filter { 
+            it.type == TransactionType.EXPENSE &&
+            it.date >= budget.startDate &&
+            it.date <= budget.endDate &&
+            it.date <= currentDate
+        }
+        
+        return when (budget.type) {
+            BudgetType.TOTAL -> {
+                // 总预算：计算所有支出
+                expenseRecords.sumOf { it.amount }
+            }
+            BudgetType.CATEGORY -> {
+                // 分类预算：计算指定分类的支出
+                expenseRecords
+                    .filter { it.category == budget.categoryName }
+                    .sumOf { it.amount }
+            }
+            BudgetType.MEMBER -> {
+                // 成员预算：计算指定成员的支出
+                expenseRecords
+                    .filter { it.memberId == budget.memberId }
+                    .sumOf { it.amount }
+            }
+        }
+    }
+    
+    /**
+     * 获取总预算状态
+     */
+    suspend fun getTotalBudgetStatus(date: Date = Date()): BudgetStatus? {
+        val budget = budgetDao.getTotalBudget(date) ?: return null
+        val records = bookkeepingDao.getAllRecords().first()
+        val members = memberDao.getAllMembers().first()
+        
+        val spent = calculateSpent(budget, records, members, date)
+        val remaining = budget.amount - spent
+        val percentage = if (budget.amount > 0) spent / budget.amount else 0.0
+        
+        return BudgetStatus(
+            budget = budget,
+            spent = spent,
+            remaining = remaining,
+            percentage = percentage,
+            isOverBudget = spent > budget.amount,
+            isNearLimit = percentage >= budget.alertThreshold
+        )
+    }
+    
+    /**
+     * 获取分类预算状态
+     */
+    fun getCategoryBudgetStatuses(date: Date = Date()): Flow<List<BudgetStatus>> {
+        return combine(
+            budgetDao.getCategoryBudgetsForDate(date),
+            bookkeepingDao.getAllRecords(),
+            memberDao.getAllMembers()
+        ) { budgets, records, members ->
+            budgets.map { budget ->
+                val spent = calculateSpent(budget, records, members, date)
+                val remaining = budget.amount - spent
+                val percentage = if (budget.amount > 0) spent / budget.amount else 0.0
+                
+                BudgetStatus(
+                    budget = budget,
+                    spent = spent,
+                    remaining = remaining,
+                    percentage = percentage,
+                    isOverBudget = spent > budget.amount,
+                    isNearLimit = percentage >= budget.alertThreshold
+                )
+            }
+        }
+    }
+    
+    /**
+     * 获取成员预算状态
+     */
+    fun getMemberBudgetStatuses(date: Date = Date()): Flow<List<BudgetStatus>> {
+        return combine(
+            budgetDao.getMemberBudgetsForDate(date),
+            bookkeepingDao.getAllRecords(),
+            memberDao.getAllMembers()
+        ) { budgets, records, members ->
+            budgets.map { budget ->
+                val spent = calculateSpent(budget, records, members, date)
+                val remaining = budget.amount - spent
+                val percentage = if (budget.amount > 0) spent / budget.amount else 0.0
+                
+                BudgetStatus(
+                    budget = budget,
+                    spent = spent,
+                    remaining = remaining,
+                    percentage = percentage,
+                    isOverBudget = spent > budget.amount,
+                    isNearLimit = percentage >= budget.alertThreshold
+                )
+            }
+        }
+    }
+    
+    /**
+     * 检查是否有预算超支或接近限制
+     */
+    suspend fun checkBudgetAlerts(date: Date = Date()): List<BudgetStatus> {
+        val allStatuses = getActiveBudgetStatuses(date).first()
+        return allStatuses.filter { it.isOverBudget || it.isNearLimit }
+    }
+    
+    /**
+     * 更新预算启用状态
+     */
+    suspend fun updateBudgetEnabled(budgetId: Int, enabled: Boolean) {
+        budgetDao.updateBudgetEnabled(budgetId, enabled)
+    }
+    
+    /**
+     * 清理过期的禁用预算
+     */
+    suspend fun cleanupExpiredBudgets() {
+        budgetDao.deleteExpiredBudgets(Date())
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/data/Converters.kt b/app/src/main/java/com/yovinchen/bookkeeping/data/Converters.kt
index b23692a..a9b249b 100644
--- a/app/src/main/java/com/yovinchen/bookkeeping/data/Converters.kt
+++ b/app/src/main/java/com/yovinchen/bookkeeping/data/Converters.kt
@@ -1,6 +1,7 @@
 package com.yovinchen.bookkeeping.data
 
 import androidx.room.TypeConverter
+import com.yovinchen.bookkeeping.model.BudgetType
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 import java.util.*
@@ -29,4 +30,14 @@ class Converters {
     fun toDate(timestamp: String?): Date? {
         return timestamp?.let { Date(it.toLong()) }
     }
+    
+    @TypeConverter
+    fun fromBudgetType(budgetType: BudgetType?): String? {
+        return budgetType?.name
+    }
+    
+    @TypeConverter
+    fun toBudgetType(budgetType: String?): BudgetType? {
+        return budgetType?.let { BudgetType.valueOf(it) }
+    }
 }
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/data/SettingsDao.kt b/app/src/main/java/com/yovinchen/bookkeeping/data/SettingsDao.kt
new file mode 100644
index 0000000..0517085
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/data/SettingsDao.kt
@@ -0,0 +1,35 @@
+package com.yovinchen.bookkeeping.data
+
+import androidx.room.*
+import com.yovinchen.bookkeeping.model.Settings
+import kotlinx.coroutines.flow.Flow
+
+@Dao
+interface SettingsDao {
+    @Query("SELECT * FROM settings WHERE id = 1")
+    fun getSettings(): Flow<Settings?>
+    
+    @Query("SELECT * FROM settings WHERE id = 1")
+    suspend fun getSettingsOnce(): Settings?
+    
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun updateSettings(settings: Settings)
+    
+    @Query("UPDATE settings SET monthStartDay = :day WHERE id = 1")
+    suspend fun updateMonthStartDay(day: Int)
+    
+    @Query("UPDATE settings SET themeMode = :mode WHERE id = 1")
+    suspend fun updateThemeMode(mode: String)
+    
+    @Query("UPDATE settings SET autoBackupEnabled = :enabled WHERE id = 1")
+    suspend fun updateAutoBackupEnabled(enabled: Boolean)
+    
+    @Query("UPDATE settings SET autoBackupInterval = :interval WHERE id = 1")
+    suspend fun updateAutoBackupInterval(interval: Int)
+    
+    @Query("UPDATE settings SET lastBackupTime = :time WHERE id = 1")
+    suspend fun updateLastBackupTime(time: Long)
+    
+    @Query("UPDATE settings SET encryptBackup = :encrypt WHERE id = 1")
+    suspend fun updateEncryptBackup(encrypt: Boolean)
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/data/SettingsRepository.kt b/app/src/main/java/com/yovinchen/bookkeeping/data/SettingsRepository.kt
new file mode 100644
index 0000000..481bec6
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/data/SettingsRepository.kt
@@ -0,0 +1,45 @@
+package com.yovinchen.bookkeeping.data
+
+import com.yovinchen.bookkeeping.model.Settings
+import kotlinx.coroutines.flow.Flow
+
+class SettingsRepository(private val settingsDao: SettingsDao) {
+    
+    fun getSettings(): Flow<Settings?> = settingsDao.getSettings()
+    
+    suspend fun getSettingsOnce(): Settings {
+        return settingsDao.getSettingsOnce() ?: Settings()
+    }
+    
+    suspend fun updateSettings(settings: Settings) {
+        settingsDao.updateSettings(settings)
+    }
+    
+    suspend fun updateMonthStartDay(day: Int) {
+        // 确保日期在有效范围内 (1-28)
+        val validDay = day.coerceIn(1, 28)
+        settingsDao.updateMonthStartDay(validDay)
+    }
+    
+    suspend fun updateThemeMode(mode: String) {
+        settingsDao.updateThemeMode(mode)
+    }
+    
+    suspend fun updateAutoBackupEnabled(enabled: Boolean) {
+        settingsDao.updateAutoBackupEnabled(enabled)
+    }
+    
+    suspend fun updateAutoBackupInterval(interval: Int) {
+        settingsDao.updateAutoBackupInterval(interval)
+    }
+    
+    suspend fun updateLastBackupTime(time: Long) {
+        settingsDao.updateLastBackupTime(time)
+    }
+    
+    suspend fun ensureSettingsExist() {
+        if (settingsDao.getSettingsOnce() == null) {
+            settingsDao.updateSettings(Settings())
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/model/Budget.kt b/app/src/main/java/com/yovinchen/bookkeeping/model/Budget.kt
new file mode 100644
index 0000000..7616bce
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/model/Budget.kt
@@ -0,0 +1,86 @@
+package com.yovinchen.bookkeeping.model
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+import java.util.Date
+
+/**
+ * 预算实体类
+ * 用于设置和跟踪月度预算、分类预算和成员预算
+ */
+@Entity(tableName = "budgets")
+data class Budget(
+    @PrimaryKey(autoGenerate = true)
+    val id: Int = 0,
+    
+    /**
+     * 预算类型：TOTAL（总预算）, CATEGORY（分类预算）, MEMBER（成员预算）
+     */
+    val type: BudgetType,
+    
+    /**
+     * 预算关联的分类名称（仅在 type 为 CATEGORY 时使用）
+     */
+    val categoryName: String? = null,
+    
+    /**
+     * 预算关联的成员ID（仅在 type 为 MEMBER 时使用）
+     */
+    val memberId: Int? = null,
+    
+    /**
+     * 预算金额
+     */
+    val amount: Double,
+    
+    /**
+     * 预算生效开始日期
+     */
+    val startDate: Date,
+    
+    /**
+     * 预算生效结束日期
+     */
+    val endDate: Date,
+    
+    /**
+     * 是否启用此预算
+     */
+    val isEnabled: Boolean = true,
+    
+    /**
+     * 提醒阈值（百分比，如 0.8 表示达到 80% 时提醒）
+     */
+    val alertThreshold: Double = 0.8,
+    
+    /**
+     * 创建时间
+     */
+    val createdAt: Date = Date(),
+    
+    /**
+     * 更新时间
+     */
+    val updatedAt: Date = Date()
+)
+
+/**
+ * 预算类型枚举
+ */
+enum class BudgetType {
+    TOTAL,      // 总预算
+    CATEGORY,   // 分类预算
+    MEMBER      // 成员预算
+}
+
+/**
+ * 预算状态数据类，用于展示预算使用情况
+ */
+data class BudgetStatus(
+    val budget: Budget,
+    val spent: Double,          // 已花费金额
+    val remaining: Double,      // 剩余金额
+    val percentage: Double,     // 使用百分比
+    val isOverBudget: Boolean,  // 是否超预算
+    val isNearLimit: Boolean    // 是否接近预算限制
+)
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/model/Settings.kt b/app/src/main/java/com/yovinchen/bookkeeping/model/Settings.kt
new file mode 100644
index 0000000..daf153b
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/model/Settings.kt
@@ -0,0 +1,15 @@
+package com.yovinchen.bookkeeping.model
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+@Entity(tableName = "settings")
+data class Settings(
+    @PrimaryKey val id: Int = 1,
+    val monthStartDay: Int = 1, // 月度开始日期，1-28，默认为1号
+    val themeMode: String = "FOLLOW_SYSTEM", // 主题模式：FOLLOW_SYSTEM, LIGHT, DARK
+    val autoBackupEnabled: Boolean = false, // 自动备份开关
+    val autoBackupInterval: Int = 7, // 自动备份间隔（天）
+    val lastBackupTime: Long = 0L, // 上次备份时间
+    val encryptBackup: Boolean = true // 备份加密开关，默认开启
+)
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/ui/screen/SettingsScreen.kt b/app/src/main/java/com/yovinchen/bookkeeping/ui/screen/SettingsScreen.kt
index a015d78..ea59a9f 100644
--- a/app/src/main/java/com/yovinchen/bookkeeping/ui/screen/SettingsScreen.kt
+++ b/app/src/main/java/com/yovinchen/bookkeeping/ui/screen/SettingsScreen.kt
@@ -4,15 +4,22 @@ import android.content.Context
 import android.widget.Toast
 import androidx.activity.ComponentActivity
 import androidx.appcompat.app.AppCompatActivity
+import androidx.compose.foundation.BorderStroke
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.lazy.grid.GridCells
+import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
+import androidx.compose.foundation.lazy.grid.items
+import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.*
 import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
+import com.yovinchen.bookkeeping.model.Settings
 import com.yovinchen.bookkeeping.model.ThemeMode
 import com.yovinchen.bookkeeping.ui.components.*
 import com.yovinchen.bookkeeping.ui.dialog.*
@@ -36,7 +43,11 @@ fun SettingsScreen(
     val categories by viewModel.categories.collectAsState()
     val selectedType by viewModel.selectedCategoryType.collectAsState()
     val members by memberViewModel.allMembers.collectAsState(initial = emptyList())
+    val monthStartDay by viewModel.monthStartDay.collectAsState()
+    val settings by viewModel.settings.collectAsState()
     val context = LocalContext.current
+    
+    var showMonthStartDayDialog by remember { mutableStateOf(false) }
 
     Column(modifier = Modifier.fillMaxSize()) {
         // 成员管理设置项
@@ -81,6 +92,15 @@ fun SettingsScreen(
             },
             modifier = Modifier.clickable { showThemeDialog = true }
         )
+        
+        HorizontalDivider()
+        
+        // 月度开始日期设置项
+        ListItem(
+            headlineContent = { Text("月度开始日期") },
+            supportingContent = { Text("每月从${monthStartDay}号开始计算") },
+            modifier = Modifier.clickable { showMonthStartDayDialog = true }
+        )
 
         if (showThemeDialog) {
             AlertDialog(
@@ -144,6 +164,76 @@ fun SettingsScreen(
                 }
             )
         }
+        
+        // 月度开始日期对话框
+        if (showMonthStartDayDialog) {
+            AlertDialog(
+                onDismissRequest = { showMonthStartDayDialog = false },
+                title = { Text("选择月度开始日期") },
+                text = {
+                    Column {
+                        Text("选择每月记账的开始日期（1-28号）")
+                        Spacer(modifier = Modifier.height(16.dp))
+                        
+                        // 日期选择器
+                        val days = (1..28).toList()
+                        LazyVerticalGrid(
+                            columns = GridCells.Fixed(7),
+                            modifier = Modifier.fillMaxWidth().height(280.dp),
+                            contentPadding = PaddingValues(4.dp),
+                            verticalArrangement = Arrangement.spacedBy(4.dp),
+                            horizontalArrangement = Arrangement.spacedBy(4.dp)
+                        ) {
+                            items(days) { day ->
+                                Surface(
+                                    onClick = {
+                                        viewModel.setMonthStartDay(day)
+                                        showMonthStartDayDialog = false
+                                    },
+                                    shape = RoundedCornerShape(8.dp),
+                                    color = if (day == monthStartDay) {
+                                        MaterialTheme.colorScheme.primaryContainer
+                                    } else {
+                                        MaterialTheme.colorScheme.surface
+                                    },
+                                    border = BorderStroke(
+                                        width = 1.dp,
+                                        color = if (day == monthStartDay) {
+                                            MaterialTheme.colorScheme.primary
+                                        } else {
+                                            MaterialTheme.colorScheme.outline
+                                        }
+                                    ),
+                                    modifier = Modifier
+                                        .fillMaxWidth()
+                                        .aspectRatio(1f)
+                                ) {
+                                    Box(
+                                        contentAlignment = Alignment.Center,
+                                        modifier = Modifier.fillMaxSize()
+                                    ) {
+                                        Text(
+                                            text = day.toString(),
+                                            style = MaterialTheme.typography.bodyMedium,
+                                            color = if (day == monthStartDay) {
+                                                MaterialTheme.colorScheme.onPrimaryContainer
+                                            } else {
+                                                MaterialTheme.colorScheme.onSurface
+                                            }
+                                        )
+                                    }
+                                }
+                            }
+                        }
+                    }
+                },
+                confirmButton = {
+                    TextButton(onClick = { showMonthStartDayDialog = false }) {
+                        Text("取消")
+                    }
+                }
+            )
+        }
 
         // 备份对话框
         if (showBackupDialog) {
@@ -189,6 +279,29 @@ fun SettingsScreen(
                                 style = MaterialTheme.typography.bodySmall
                             )
                         }
+                        
+                        HorizontalDivider(modifier = Modifier.padding(vertical = 8.dp))
+                        
+                        // 备份加密开关
+                        Row(
+                            modifier = Modifier.fillMaxWidth(),
+                            verticalAlignment = Alignment.CenterVertically
+                        ) {
+                            Text("备份加密", modifier = Modifier.weight(1f))
+                            Switch(
+                                checked = settings?.encryptBackup ?: true,
+                                onCheckedChange = { enabled ->
+                                    viewModel.updateSettings(
+                                        settings?.copy(encryptBackup = enabled) ?: Settings(encryptBackup = enabled)
+                                    )
+                                }
+                            )
+                        }
+                        Text(
+                            "开启后，导出的备份文件将被加密保护",
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant
+                        )
                     }
                 },
                 confirmButton = {
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/utils/DateUtils.kt b/app/src/main/java/com/yovinchen/bookkeeping/utils/DateUtils.kt
new file mode 100644
index 0000000..a525ad6
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/utils/DateUtils.kt
@@ -0,0 +1,85 @@
+package com.yovinchen.bookkeeping.utils
+
+import java.time.LocalDate
+import java.time.YearMonth
+import java.time.ZoneId
+import java.util.Date
+
+object DateUtils {
+    
+    /**
+     * 根据月度开始日期计算给定日期所属的记账月份
+     * @param date 要判断的日期
+     * @param monthStartDay 月度开始日期（1-28）
+     * @return 该日期所属的记账月份
+     */
+    fun getAccountingMonth(date: Date, monthStartDay: Int): YearMonth {
+        val localDate = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate()
+        return getAccountingMonth(localDate, monthStartDay)
+    }
+    
+    /**
+     * 根据月度开始日期计算给定日期所属的记账月份
+     * @param date 要判断的日期
+     * @param monthStartDay 月度开始日期（1-28）
+     * @return 该日期所属的记账月份
+     */
+    fun getAccountingMonth(date: LocalDate, monthStartDay: Int): YearMonth {
+        val dayOfMonth = date.dayOfMonth
+        
+        return if (dayOfMonth >= monthStartDay) {
+            // 当前日期大于等于开始日期，属于当前月
+            YearMonth.from(date)
+        } else {
+            // 当前日期小于开始日期，属于上个月
+            YearMonth.from(date.minusMonths(1))
+        }
+    }
+    
+    /**
+     * 获取记账月份的开始日期
+     * @param yearMonth 记账月份
+     * @param monthStartDay 月度开始日期（1-28）
+     * @return 该记账月份的开始日期
+     */
+    fun getMonthStartDate(yearMonth: YearMonth, monthStartDay: Int): LocalDate {
+        return yearMonth.atDay(monthStartDay)
+    }
+    
+    /**
+     * 获取记账月份的结束日期
+     * @param yearMonth 记账月份
+     * @param monthStartDay 月度开始日期（1-28）
+     * @return 该记账月份的结束日期
+     */
+    fun getMonthEndDate(yearMonth: YearMonth, monthStartDay: Int): LocalDate {
+        val nextMonth = yearMonth.plusMonths(1)
+        return nextMonth.atDay(monthStartDay).minusDays(1)
+    }
+    
+    /**
+     * 检查日期是否在指定的记账月份内
+     * @param date 要检查的日期
+     * @param yearMonth 记账月份
+     * @param monthStartDay 月度开始日期（1-28）
+     * @return 是否在该记账月份内
+     */
+    fun isInAccountingMonth(date: Date, yearMonth: YearMonth, monthStartDay: Int): Boolean {
+        val localDate = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate()
+        return isInAccountingMonth(localDate, yearMonth, monthStartDay)
+    }
+    
+    /**
+     * 检查日期是否在指定的记账月份内
+     * @param date 要检查的日期
+     * @param yearMonth 记账月份
+     * @param monthStartDay 月度开始日期（1-28）
+     * @return 是否在该记账月份内
+     */
+    fun isInAccountingMonth(date: LocalDate, yearMonth: YearMonth, monthStartDay: Int): Boolean {
+        val startDate = getMonthStartDate(yearMonth, monthStartDay)
+        val endDate = getMonthEndDate(yearMonth, monthStartDay)
+        
+        return date >= startDate && date <= endDate
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/utils/EncryptionUtils.kt b/app/src/main/java/com/yovinchen/bookkeeping/utils/EncryptionUtils.kt
new file mode 100644
index 0000000..faf399e
--- /dev/null
+++ b/app/src/main/java/com/yovinchen/bookkeeping/utils/EncryptionUtils.kt
@@ -0,0 +1,136 @@
+package com.yovinchen.bookkeeping.utils
+
+import android.security.keystore.KeyGenParameterSpec
+import android.security.keystore.KeyProperties
+import android.util.Base64
+import java.security.KeyStore
+import javax.crypto.Cipher
+import javax.crypto.KeyGenerator
+import javax.crypto.SecretKey
+import javax.crypto.spec.GCMParameterSpec
+
+/**
+ * 加密工具类，使用 Android Keystore 系统安全地存储加密密钥
+ */
+object EncryptionUtils {
+    private const val ANDROID_KEYSTORE = "AndroidKeyStore"
+    private const val TRANSFORMATION = "AES/GCM/NoPadding"
+    private const val KEY_ALIAS = "BookkeepingBackupKey"
+    private const val GCM_TAG_LENGTH = 128
+    
+    init {
+        generateKey()
+    }
+    
+    /**
+     * 生成或获取加密密钥
+     */
+    private fun generateKey() {
+        val keyStore = KeyStore.getInstance(ANDROID_KEYSTORE)
+        keyStore.load(null)
+        
+        // 如果密钥已存在，则不需要重新生成
+        if (keyStore.containsAlias(KEY_ALIAS)) {
+            return
+        }
+        
+        val keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, ANDROID_KEYSTORE)
+        val keyGenParameterSpec = KeyGenParameterSpec.Builder(
+            KEY_ALIAS,
+            KeyProperties.PURPOSE_ENCRYPT or KeyProperties.PURPOSE_DECRYPT
+        )
+            .setBlockModes(KeyProperties.BLOCK_MODE_GCM)
+            .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
+            .setRandomizedEncryptionRequired(true)
+            .build()
+        
+        keyGenerator.init(keyGenParameterSpec)
+        keyGenerator.generateKey()
+    }
+    
+    /**
+     * 获取密钥
+     */
+    private fun getKey(): SecretKey {
+        val keyStore = KeyStore.getInstance(ANDROID_KEYSTORE)
+        keyStore.load(null)
+        return keyStore.getKey(KEY_ALIAS, null) as SecretKey
+    }
+    
+    /**
+     * 加密字符串
+     * @param plainText 要加密的明文
+     * @return Base64编码的加密数据（包含IV）
+     */
+    fun encrypt(plainText: String): String {
+        val cipher = Cipher.getInstance(TRANSFORMATION)
+        cipher.init(Cipher.ENCRYPT_MODE, getKey())
+        
+        val iv = cipher.iv
+        val encryptedBytes = cipher.doFinal(plainText.toByteArray(Charsets.UTF_8))
+        
+        // 将IV和加密数据组合
+        val combined = ByteArray(iv.size + encryptedBytes.size)
+        System.arraycopy(iv, 0, combined, 0, iv.size)
+        System.arraycopy(encryptedBytes, 0, combined, iv.size, encryptedBytes.size)
+        
+        return Base64.encodeToString(combined, Base64.DEFAULT)
+    }
+    
+    /**
+     * 解密字符串
+     * @param encryptedData Base64编码的加密数据
+     * @return 解密后的明文
+     */
+    fun decrypt(encryptedData: String): String {
+        val combined = Base64.decode(encryptedData, Base64.DEFAULT)
+        
+        // 提取IV（前12字节）
+        val iv = combined.sliceArray(0..11)
+        val encryptedBytes = combined.sliceArray(12 until combined.size)
+        
+        val cipher = Cipher.getInstance(TRANSFORMATION)
+        val spec = GCMParameterSpec(GCM_TAG_LENGTH, iv)
+        cipher.init(Cipher.DECRYPT_MODE, getKey(), spec)
+        
+        val decryptedBytes = cipher.doFinal(encryptedBytes)
+        return String(decryptedBytes, Charsets.UTF_8)
+    }
+    
+    /**
+     * 加密字节数组
+     * @param data 要加密的数据
+     * @return 加密后的数据（包含IV）
+     */
+    fun encryptBytes(data: ByteArray): ByteArray {
+        val cipher = Cipher.getInstance(TRANSFORMATION)
+        cipher.init(Cipher.ENCRYPT_MODE, getKey())
+        
+        val iv = cipher.iv
+        val encryptedBytes = cipher.doFinal(data)
+        
+        // 将IV和加密数据组合
+        val combined = ByteArray(iv.size + encryptedBytes.size)
+        System.arraycopy(iv, 0, combined, 0, iv.size)
+        System.arraycopy(encryptedBytes, 0, combined, iv.size, encryptedBytes.size)
+        
+        return combined
+    }
+    
+    /**
+     * 解密字节数组
+     * @param encryptedData 加密的数据
+     * @return 解密后的数据
+     */
+    fun decryptBytes(encryptedData: ByteArray): ByteArray {
+        // 提取IV（前12字节）
+        val iv = encryptedData.sliceArray(0..11)
+        val encryptedBytes = encryptedData.sliceArray(12 until encryptedData.size)
+        
+        val cipher = Cipher.getInstance(TRANSFORMATION)
+        val spec = GCMParameterSpec(GCM_TAG_LENGTH, iv)
+        cipher.init(Cipher.DECRYPT_MODE, getKey(), spec)
+        
+        return cipher.doFinal(encryptedBytes)
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/utils/FilePickerUtil.kt b/app/src/main/java/com/yovinchen/bookkeeping/utils/FilePickerUtil.kt
index 59493e6..4d03ce2 100644
--- a/app/src/main/java/com/yovinchen/bookkeeping/utils/FilePickerUtil.kt
+++ b/app/src/main/java/com/yovinchen/bookkeeping/utils/FilePickerUtil.kt
@@ -107,11 +107,16 @@ object FilePickerUtil {
     private fun isValidFileType(fileName: String, mimeType: String?): Boolean {
         val fileExtension = fileName.lowercase()
         return fileExtension.endsWith(".csv") || 
+               fileExtension.endsWith(".csv.enc") ||
                fileExtension.endsWith(".xlsx") ||
+               fileExtension.endsWith(".xlsx.enc") ||
                fileExtension.endsWith(".xls") ||
+               fileExtension.endsWith(".xls.enc") ||
+               fileExtension.endsWith(".enc") ||
                mimeType == "text/csv" ||
                mimeType == "application/vnd.ms-excel" ||
-               mimeType == "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
+               mimeType == "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" ||
+               mimeType == "application/octet-stream" // 加密文件可能被识别为二进制流
     }
 
     /**
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/AnalysisViewModel.kt b/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/AnalysisViewModel.kt
index eaba8e9..e035ced 100644
--- a/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/AnalysisViewModel.kt
+++ b/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/AnalysisViewModel.kt
@@ -4,21 +4,22 @@ import android.app.Application
 import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.viewModelScope
 import com.yovinchen.bookkeeping.data.BookkeepingDatabase
+import com.yovinchen.bookkeeping.data.SettingsRepository
 import com.yovinchen.bookkeeping.model.AnalysisType
 import com.yovinchen.bookkeeping.model.BookkeepingRecord
 import com.yovinchen.bookkeeping.model.CategoryStat
 import com.yovinchen.bookkeeping.model.MemberStat
 import com.yovinchen.bookkeeping.model.TransactionType
+import com.yovinchen.bookkeeping.utils.DateUtils
 import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
-import java.time.LocalDateTime
 import java.time.YearMonth
-import java.time.ZoneId
 import java.util.*
 
 class AnalysisViewModel(application: Application) : AndroidViewModel(application) {
     private val recordDao = BookkeepingDatabase.getDatabase(application).bookkeepingDao()
     private val memberDao = BookkeepingDatabase.getDatabase(application).memberDao()
+    private val settingsRepository = SettingsRepository(BookkeepingDatabase.getDatabase(application).settingsDao())
 
     private val _startMonth = MutableStateFlow(YearMonth.now())
     val startMonth: StateFlow<YearMonth> = _startMonth.asStateFlow()
@@ -38,16 +39,41 @@ class AnalysisViewModel(application: Application) : AndroidViewModel(application
     private val _records = MutableStateFlow<List<BookkeepingRecord>>(emptyList())
     val records: StateFlow<List<BookkeepingRecord>> = _records.asStateFlow()
 
+    // 存储月度开始日期设置
+    private val _monthStartDay = MutableStateFlow(1)
+    val monthStartDay: StateFlow<Int> = _monthStartDay.asStateFlow()
+
     init {
+        // 订阅设置变化，获取月度开始日期
         viewModelScope.launch {
-            combine(startMonth, endMonth, selectedAnalysisType) { start, end, type ->
-                Triple(start, end, type)
-            }.collect { (start, end, type) ->
-                updateStats(start, end, type)
+            settingsRepository.getSettings().collect { settings ->
+                _monthStartDay.value = settings?.monthStartDay ?: 1
+            }
+        }
+        
+        // 当月度开始日期、起始月份、结束月份或分析类型变化时，更新统计数据
+        viewModelScope.launch {
+            combine(
+                startMonth, 
+                endMonth, 
+                selectedAnalysisType,
+                monthStartDay
+            ) { start, end, type, startDay ->
+                UpdateParams(start, end, type, startDay)
+            }.collect { params ->
+                updateStats(params.start, params.end, params.type, params.startDay)
             }
         }
     }
 
+    // 用于传递更新参数的数据类
+    private data class UpdateParams(
+        val start: YearMonth,
+        val end: YearMonth,
+        val type: AnalysisType,
+        val startDay: Int
+    )
+
     fun setStartMonth(month: YearMonth) {
         _startMonth.value = month
     }
@@ -60,16 +86,16 @@ class AnalysisViewModel(application: Application) : AndroidViewModel(application
         _selectedAnalysisType.value = type
     }
 
-    private suspend fun updateStats(startMonth: YearMonth, endMonth: YearMonth, type: AnalysisType) {
+    private suspend fun updateStats(startMonth: YearMonth, endMonth: YearMonth, type: AnalysisType, monthStartDay: Int) {
         val records = recordDao.getAllRecords().first()
         
-        // 过滤日期范围内的记录
-        val monthRecords = records.filter {
-            val recordDate = Date(it.date.time)
-            val localDateTime = LocalDateTime.ofInstant(recordDate.toInstant(), ZoneId.systemDefault())
-            val yearMonth = YearMonth.from(localDateTime)
-            yearMonth.isAfter(startMonth.minusMonths(1)) && 
-            yearMonth.isBefore(endMonth.plusMonths(1))
+        // 使用 DateUtils 过滤日期范围内的记录
+        val monthRecords = records.filter { record ->
+            val recordDate = Date(record.date.time)
+            val accountingMonth = DateUtils.getAccountingMonth(recordDate, monthStartDay)
+            
+            // 检查记账月份是否在选定的范围内
+            accountingMonth >= startMonth && accountingMonth <= endMonth
         }
 
         // 更新记录数据
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/HomeViewModel.kt b/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/HomeViewModel.kt
index daebbf3..53e85bb 100644
--- a/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/HomeViewModel.kt
+++ b/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/HomeViewModel.kt
@@ -4,10 +4,12 @@ import android.app.Application
 import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.viewModelScope
 import com.yovinchen.bookkeeping.data.BookkeepingDatabase
+import com.yovinchen.bookkeeping.data.SettingsRepository
 import com.yovinchen.bookkeeping.model.BookkeepingRecord
 import com.yovinchen.bookkeeping.model.Category
 import com.yovinchen.bookkeeping.model.Member
 import com.yovinchen.bookkeeping.model.TransactionType
+import com.yovinchen.bookkeeping.utils.DateUtils
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
@@ -18,9 +20,26 @@ import java.util.*
 
 @OptIn(ExperimentalCoroutinesApi::class)
 class HomeViewModel(application: Application) : AndroidViewModel(application) {
-    private val bookkeepingDao = BookkeepingDatabase.getDatabase(application).bookkeepingDao()
-    private val memberDao = BookkeepingDatabase.getDatabase(application).memberDao()
-    private val categoryDao = BookkeepingDatabase.getDatabase(application).categoryDao()
+    private val database = BookkeepingDatabase.getDatabase(application)
+    private val bookkeepingDao = database.bookkeepingDao()
+    private val memberDao = database.memberDao()
+    private val categoryDao = database.categoryDao()
+    private val settingsRepository = SettingsRepository(database.settingsDao())
+    
+    // 设置相关
+    private val _monthStartDay = MutableStateFlow(1)
+    val monthStartDay: StateFlow<Int> = _monthStartDay.asStateFlow()
+    
+    init {
+        viewModelScope.launch {
+            settingsRepository.ensureSettingsExist()
+            settingsRepository.getSettings().collect { settings ->
+                settings?.let {
+                    _monthStartDay.value = it.monthStartDay
+                }
+            }
+        }
+    }
 
     private val _selectedRecordType = MutableStateFlow<TransactionType?>(null)
     val selectedRecordType: StateFlow<TransactionType?> = _selectedRecordType.asStateFlow()
@@ -56,17 +75,13 @@ class HomeViewModel(application: Application) : AndroidViewModel(application) {
         allRecords,
         _selectedRecordType,
         _selectedMonth,
-        _selectedMember
-    ) { records, selectedType, selectedMonth, selectedMember ->
+        _selectedMember,
+        _monthStartDay
+    ) { records, selectedType, selectedMonth, selectedMember, monthStartDay ->
         records
             .filter { record ->
-                val recordDate = record.date.toInstant()
-                    .atZone(ZoneId.systemDefault())
-                    .toLocalDate()
-                val recordYearMonth = YearMonth.from(recordDate)
-
                 val typeMatches = selectedType?.let { record.type == it } ?: true
-                val monthMatches = recordYearMonth == selectedMonth
+                val monthMatches = DateUtils.isInAccountingMonth(record.date, selectedMonth, monthStartDay)
                 val memberMatches = selectedMember?.let { record.memberId == it.id } ?: true
 
                 monthMatches && memberMatches && typeMatches
@@ -90,16 +105,12 @@ class HomeViewModel(application: Application) : AndroidViewModel(application) {
     val totalIncome = combine(
         allRecords,
         _selectedMonth,
-        _selectedMember
-    ) { records, selectedMonth, selectedMember ->
+        _selectedMember,
+        _monthStartDay
+    ) { records, selectedMonth, selectedMember, monthStartDay ->
         records
             .filter { record ->
-                val recordDate = record.date.toInstant()
-                    .atZone(ZoneId.systemDefault())
-                    .toLocalDate()
-                val recordYearMonth = YearMonth.from(recordDate)
-                
-                val monthMatches = recordYearMonth == selectedMonth
+                val monthMatches = DateUtils.isInAccountingMonth(record.date, selectedMonth, monthStartDay)
                 val memberMatches = selectedMember?.let { record.memberId == it.id } ?: true
                 val typeMatches = record.type == TransactionType.INCOME
 
@@ -115,16 +126,12 @@ class HomeViewModel(application: Application) : AndroidViewModel(application) {
     val totalExpense = combine(
         allRecords,
         _selectedMonth,
-        _selectedMember
-    ) { records, selectedMonth, selectedMember ->
+        _selectedMember,
+        _monthStartDay
+    ) { records, selectedMonth, selectedMember, monthStartDay ->
         records
             .filter { record ->
-                val recordDate = record.date.toInstant()
-                    .atZone(ZoneId.systemDefault())
-                    .toLocalDate()
-                val recordYearMonth = YearMonth.from(recordDate)
-                
-                val monthMatches = recordYearMonth == selectedMonth
+                val monthMatches = DateUtils.isInAccountingMonth(record.date, selectedMonth, monthStartDay)
                 val memberMatches = selectedMember?.let { record.memberId == it.id } ?: true
                 val typeMatches = record.type == TransactionType.EXPENSE
 
diff --git a/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/SettingsViewModel.kt b/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/SettingsViewModel.kt
index 840a7c4..f9709b3 100644
--- a/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/SettingsViewModel.kt
+++ b/app/src/main/java/com/yovinchen/bookkeeping/viewmodel/SettingsViewModel.kt
@@ -9,9 +9,12 @@ import androidx.lifecycle.viewModelScope
 import com.opencsv.CSVReader
 import com.opencsv.CSVWriter
 import com.yovinchen.bookkeeping.data.BookkeepingDatabase
+import com.yovinchen.bookkeeping.data.SettingsRepository
 import com.yovinchen.bookkeeping.model.BookkeepingRecord
 import com.yovinchen.bookkeeping.model.Category
+import com.yovinchen.bookkeeping.model.Settings
 import com.yovinchen.bookkeeping.model.TransactionType
+import com.yovinchen.bookkeeping.utils.EncryptionUtils
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.delay
@@ -28,6 +31,7 @@ import org.apache.poi.xssf.usermodel.XSSFWorkbook
 import java.io.File
 import java.io.FileReader
 import java.io.FileWriter
+import java.io.StringWriter
 import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
@@ -38,8 +42,36 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
     private val database = BookkeepingDatabase.getDatabase(application)
     private val dao = database.bookkeepingDao()
     private val memberDao = database.memberDao()
+    private val settingsRepository = SettingsRepository(database.settingsDao())
+    
+    // 设置相关的状态
+    val settings: StateFlow<Settings?> = settingsRepository.getSettings()
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5000),
+            initialValue = null
+        )
+    
     private val _isAutoBackupEnabled = MutableStateFlow(false)
     val isAutoBackupEnabled: StateFlow<Boolean> = _isAutoBackupEnabled.asStateFlow()
+    
+    private val _monthStartDay = MutableStateFlow(1)
+    val monthStartDay: StateFlow<Int> = _monthStartDay.asStateFlow()
+    
+    init {
+        viewModelScope.launch {
+            // 确保设置存在
+            settingsRepository.ensureSettingsExist()
+            
+            // 监听设置变化
+            settings.collect { settings ->
+                settings?.let {
+                    _isAutoBackupEnabled.value = it.autoBackupEnabled
+                    _monthStartDay.value = it.monthStartDay
+                }
+            }
+        }
+    }
 
     private val _selectedCategoryType = MutableStateFlow(TransactionType.EXPENSE)
     val selectedCategoryType: StateFlow<TransactionType> = _selectedCategoryType.asStateFlow()
@@ -85,11 +117,19 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
     fun setAutoBackup(enabled: Boolean) {
         viewModelScope.launch {
             _isAutoBackupEnabled.value = enabled
+            settingsRepository.updateAutoBackupEnabled(enabled)
             if (enabled) {
                 schedulePeriodicBackup()
             }
         }
     }
+    
+    fun setMonthStartDay(day: Int) {
+        viewModelScope.launch {
+            _monthStartDay.value = day
+            settingsRepository.updateMonthStartDay(day)
+        }
+    }
 
     private fun schedulePeriodicBackup() {
         viewModelScope.launch(Dispatchers.IO) {
@@ -119,15 +159,24 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
     fun exportToCSV(context: Context, customDir: File? = null) {
         viewModelScope.launch(Dispatchers.IO) {
             try {
+                val currentSettings = settings.value ?: Settings()
                 val timestamp =
                     SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())
-                val fileName = "bookkeeping_backup_$timestamp.csv"
+                val shouldEncrypt = currentSettings.encryptBackup
+                val fileName = if (shouldEncrypt) {
+                    "bookkeeping_backup_$timestamp.csv.enc"
+                } else {
+                    "bookkeeping_backup_$timestamp.csv"
+                }
                 val downloadsDir = customDir ?: Environment.getExternalStoragePublicDirectory(
                     Environment.DIRECTORY_DOWNLOADS
                 )
                 val file = File(downloadsDir, fileName)
 
-                CSVWriter(FileWriter(file)).use { writer ->
+                // 先创建CSV内容到字符串
+                val csvContent = StringWriter().use { stringWriter ->
+                    val writer = CSVWriter(stringWriter)
+                    
                     // 写入头部
                     writer.writeNext(arrayOf("日期", "类型", "金额", "类别", "备注", "成员"))
 
@@ -151,11 +200,25 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
                             )
                         )
                     }
+                    writer.close()
+                    stringWriter.toString()
+                }
+
+                // 根据设置决定是否加密
+                if (shouldEncrypt) {
+                    val encryptedContent = EncryptionUtils.encrypt(csvContent)
+                    file.writeText(encryptedContent)
+                } else {
+                    file.writeText(csvContent)
                 }
 
                 withContext(Dispatchers.Main) {
-                    Toast.makeText(context, "CSV导出成功: ${file.absolutePath}", Toast.LENGTH_LONG)
-                        .show()
+                    val message = if (shouldEncrypt) {
+                        "CSV导出成功（已加密）: ${file.absolutePath}"
+                    } else {
+                        "CSV导出成功: ${file.absolutePath}"
+                    }
+                    Toast.makeText(context, message, Toast.LENGTH_LONG).show()
                 }
             } catch (e: Exception) {
                 e.printStackTrace()
@@ -169,6 +232,9 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
     fun exportToExcel(context: Context) {
         viewModelScope.launch(Dispatchers.IO) {
             try {
+                val currentSettings = settings.value ?: Settings()
+                val shouldEncrypt = currentSettings.encryptBackup
+                
                 val workbook = XSSFWorkbook()
                 val sheet = workbook.createSheet("账目记录")
 
@@ -201,18 +267,39 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
 
                 val timestamp =
                     SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())
-                val fileName = "bookkeeping_backup_$timestamp.xlsx"
+                val fileName = if (shouldEncrypt) {
+                    "bookkeeping_backup_$timestamp.xlsx.enc"
+                } else {
+                    "bookkeeping_backup_$timestamp.xlsx"
+                }
                 val downloadsDir =
                     Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
                 val file = File(downloadsDir, fileName)
 
-                workbook.write(file.outputStream())
+                if (shouldEncrypt) {
+                    // 将 workbook 写入字节数组
+                    val byteArrayOutputStream = java.io.ByteArrayOutputStream()
+                    workbook.write(byteArrayOutputStream)
+                    val excelBytes = byteArrayOutputStream.toByteArray()
+                    
+                    // 加密字节数组
+                    val encryptedBytes = EncryptionUtils.encryptBytes(excelBytes)
+                    
+                    // 写入加密文件
+                    file.writeBytes(encryptedBytes)
+                } else {
+                    workbook.write(file.outputStream())
+                }
+                
                 workbook.close()
 
                 withContext(Dispatchers.Main) {
-                    Toast.makeText(
-                        context, "Excel导出成功: ${file.absolutePath}", Toast.LENGTH_LONG
-                    ).show()
+                    val message = if (shouldEncrypt) {
+                        "Excel导出成功（已加密）: ${file.absolutePath}"
+                    } else {
+                        "Excel导出成功: ${file.absolutePath}"
+                    }
+                    Toast.makeText(context, message, Toast.LENGTH_LONG).show()
                 }
             } catch (e: Exception) {
                 e.printStackTrace()
@@ -227,10 +314,30 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
         viewModelScope.launch(Dispatchers.IO) {
             try {
                 when {
+                    backupFile.name.endsWith(".csv.enc", ignoreCase = true) -> {
+                        // 解密CSV文件
+                        val encryptedContent = backupFile.readText()
+                        val decryptedContent = EncryptionUtils.decrypt(encryptedContent)
+                        val tempFile = File(context.cacheDir, "temp_decrypted.csv")
+                        tempFile.writeText(decryptedContent)
+                        restoreFromCSV(tempFile)
+                        tempFile.delete()
+                    }
+                    
                     backupFile.name.endsWith(".csv", ignoreCase = true) -> {
                         restoreFromCSV(backupFile)
                     }
 
+                    backupFile.name.endsWith(".xlsx.enc", ignoreCase = true) -> {
+                        // 解密Excel文件
+                        val encryptedBytes = backupFile.readBytes()
+                        val decryptedBytes = EncryptionUtils.decryptBytes(encryptedBytes)
+                        val tempFile = File(context.cacheDir, "temp_decrypted.xlsx")
+                        tempFile.writeBytes(decryptedBytes)
+                        restoreFromExcel(tempFile)
+                        tempFile.delete()
+                    }
+                    
                     backupFile.name.endsWith(".xlsx", ignoreCase = true) -> {
                         restoreFromExcel(backupFile)
                     }
@@ -249,7 +356,11 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
             } catch (e: Exception) {
                 e.printStackTrace()
                 withContext(Dispatchers.Main) {
-                    Toast.makeText(context, "数据恢复失败: ${e.message}", Toast.LENGTH_LONG).show()
+                    val errorMessage = when {
+                        e.message?.contains("decrypt") == true -> "解密失败，请确认文件未损坏"
+                        else -> "数据恢复失败: ${e.message}"
+                    }
+                    Toast.makeText(context, errorMessage, Toast.LENGTH_LONG).show()
                 }
             }
         }
@@ -305,4 +416,10 @@ class SettingsViewModel(application: Application) : AndroidViewModel(application
     private suspend fun findMemberIdByName(name: String): Int? {
         return memberDao.getAllMembers().first().find { member -> member.name == name }?.id
     }
+    
+    fun updateSettings(settings: Settings) {
+        viewModelScope.launch {
+            settingsRepository.updateSettings(settings)
+        }
+    }
 }