Merge branch 'feature/encryption-budget' into develop

1. 备份加密功能
   - 添加 EncryptionUtils 使用 Android Keystore 安全存储密钥
   - 修改导出功能支持 CSV 和 Excel 文件加密
   - 实现加密文件的自动解密导入
   - 在设置页面添加备份加密开关

2. 预算管理基础架构
   - 创建 Budget 数据模型，支持总预算、分类预算和成员预算
   - 创建 BudgetDao 提供数据库操作接口
   - 创建 BudgetRepository 实现预算业务逻辑
   - 更新数据库版本至 v6 并添加迁移

3. 其他改进
   - 创建 CLAUDE.md 文件提供项目指导
   - 修复编译错误和类型安全问题
   - 更新 FilePickerUtil 支持加密文件格式

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.claude/settings.local.json

@@ -0,0 +1,8 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(./gradlew:*)"
+    ],
+    "deny": []
+  }
+}

.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>

.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" />

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

app/src/main/java/com/yovinchen/bookkeeping/data/BookkeepingDatabase.kt

@@ -10,6 +10,7 @@ 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
@@ -20,8 +21,8 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 
 @Database(
-    entities = [BookkeepingRecord::class, Category::class, Member::class, Settings::class],
-    version = 5,
+    entities = [BookkeepingRecord::class, Category::class, Member::class, Settings::class, Budget::class],
+    version = 6,
     exportSchema = false
 )
 @TypeConverters(Converters::class)
@@ -30,6 +31,7 @@ abstract class BookkeepingDatabase : RoomDatabase() {
     abstract fun categoryDao(): CategoryDao
     abstract fun memberDao(): MemberDao
     abstract fun settingsDao(): SettingsDao
+    abstract fun budgetDao(): BudgetDao
 
     companion object {
         private const val TAG = "BookkeepingDatabase"
@@ -147,6 +149,30 @@ abstract class BookkeepingDatabase : RoomDatabase() {
                 """)
             }
         }
+        
+        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
@@ -158,7 +184,7 @@ abstract class BookkeepingDatabase : RoomDatabase() {
                     BookkeepingDatabase::class.java,
                     "bookkeeping_database"
                 )
-                    .addMigrations(MIGRATION_1_2, MIGRATION_2_3, MIGRATION_3_4, MIGRATION_4_5)
+                    .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)

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>>
+}

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())
+    }
+}

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) }
+    }
 }

app/src/main/java/com/yovinchen/bookkeeping/data/SettingsDao.kt

@@ -29,4 +29,7 @@ interface SettingsDao {
     
     @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)
 }

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
+)

app/src/main/java/com/yovinchen/bookkeeping/model/Settings.kt

@@ -10,5 +10,6 @@ data class Settings(
     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 lastBackupTime: Long = 0L, // 上次备份时间
+    val encryptBackup: Boolean = true // 备份加密开关，默认开启
 )

app/src/main/java/com/yovinchen/bookkeeping/ui/screen/SettingsScreen.kt

@@ -19,6 +19,7 @@ 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.*
@@ -43,6 +44,7 @@ fun SettingsScreen(
     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) }
@@ -277,6 +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 = {

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)
+    }
+}

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
     }
 
     /**

app/src/main/java/com/yovinchen/bookkeeping/viewmodel/SettingsViewModel.kt

@@ -14,6 +14,7 @@ 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
@@ -30,6 +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
@@ -157,15 +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"))
 
@@ -189,11 +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()
@@ -207,6 +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")
 
@@ -239,18 +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()
@@ -265,10 +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)
                     }
@@ -287,7 +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()
                 }
             }
         }
@@ -343,4 +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)
+        }
+    }
 }