package com.example.myapplicationimport android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.tooling.preview.Preview
import android.content.ContentValues
import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
import android.util.Log
import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.interaction.MutableInteractionSource
import androidx.compose.foundation.interaction.collectIsPressedAsState
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.OutlinedTextFieldDefaults
import androidx.compose.runtime.mutableStateListOf
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.runtime.getValue
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.unit.dp
import androidx.compose.material3.Surface
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValueimport com.example.myapplication.printDatabase
import com.example.myapplication.ui.theme.MyApplicationTheme
import kotlinx.coroutines.delay
import kotlin.collections.addAll
import kotlin.text.clear// 数据类，表示数据库中的一个项目
data class Item(val id: Int? = null, val name: String, val description: String)// 数据库帮助类，用于管理数据库的创建、升级和数据操作
class DatabaseHelper(context: Context) : SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION) {companion object {private const val DATABASE_NAME = "item_database" // 数据库名称private const val DATABASE_VERSION = 1 // 数据库版本private const val TABLE_NAME = "items" // 表名private const val COLUMN_ID = "id" // ID 列名private const val COLUMN_NAME = "name" // 名称列名private const val COLUMN_DESCRIPTION = "description" // 描述列名}// 创建数据库表override fun onCreate(db: SQLiteDatabase) {val createTableQuery = "CREATE TABLE $TABLE_NAME ($COLUMN_ID INTEGER PRIMARY KEY AUTOINCREMENT, $COLUMN_NAME TEXT, $COLUMN_DESCRIPTION TEXT)"db.execSQL(createTableQuery)}// 升级数据库表override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {val dropTableQuery = "DROP TABLE IF EXISTS $TABLE_NAME"db.execSQL(dropTableQuery)onCreate(db)}// 插入一个项目fun insertItem(item: Item) {val db = writableDatabaseval values = ContentValues().apply {put(COLUMN_NAME, item.name)put(COLUMN_DESCRIPTION, item.description)}db.insert(TABLE_NAME, null, values)db.close()}// 获取所有项目fun getAllItems(): List<Item> {val db = readableDatabaseval query = "SELECT * FROM $TABLE_NAME"val cursor = db.rawQuery(query, null)val items = mutableListOf<Item>()if (cursor.moveToFirst()) {do {val id = cursor.getInt(cursor.getColumnIndexOrThrow(COLUMN_ID))val name = cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_NAME))val description = cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_DESCRIPTION))items.add(Item(id, name, description))} while (cursor.moveToNext())}cursor.close()db.close()return items}// 删除一个项目fun deleteItem(itemId: Int) {val db = writableDatabasedb.delete(TABLE_NAME, "$COLUMN_ID=?", arrayOf(itemId.toString()))db.close()}
}class MainActivity : ComponentActivity() {override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)enableEdgeToEdge()setContent {MyApplicationTheme {/*Surface(modifier = Modifier.fillMaxSize(),color = MaterialTheme.colorScheme.background){Surface(color = MaterialTheme.colorScheme.primary,modifier = Modifier.padding(vertical = 25.dp, horizontal = 8.dp)) {MainScreen()}}*/Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->Surface(color = MaterialTheme.colorScheme.primary,modifier = Modifier.padding(innerPadding)) {MainScreen()}}}}}
}@Composable
fun MainScreen() {val context = LocalContext.currentval dbHelper = remember { DatabaseHelper(context) } // 记住数据库帮助类实例var itemName by remember { mutableStateOf("") } // 项目名称输入框的值var itemDescription by remember { mutableStateOf("") } // 项目描述输入框的值val items = remember { mutableStateListOf<Item>() } // 存储项目列表val showDatabaseContent = remember { mutableStateOf(false) } // 是否显示数据库内容的标志// 创建一个 MutableInteractionSource 来跟踪按钮的交互状态val interactionSource = remember { MutableInteractionSource() }// 获取按钮是否被按下的状态val isPressed by interactionSource.collectIsPressedAsState()// 根据按钮是否被按下，选择不同的颜色val buttonColor = if (isPressed) {Color(0xFF87CEEB) // 按下时的颜色 (更深的蓝色)} else {Color(0xFFADD8E6) // 默认颜色 (浅蓝色)}items.addAll(dbHelper.getAllItems()) // 初始化时从数据库加载数据Column(modifier = Modifier.padding(1.dp)) {// 项目名称输入框OutlinedTextField(value = itemName,onValueChange = { itemName = it },label = { Text("项目名称") },modifier = Modifier.fillMaxWidth().padding(1.dp),colors = OutlinedTextFieldDefaults.colors(focusedTextColor = Color.Black, // 获得焦点时的文本颜色unfocusedTextColor = Color.Black, // 未获得焦点时的文本颜色focusedLabelColor = Color.Blue, // 获得焦点时的标签颜色unfocusedLabelColor = Color.Black, // 未获得焦点时的标签颜色cursorColor = Color.Black, // 光标颜色focusedBorderColor = Color.Blue, // 获得焦点时的边框颜色unfocusedBorderColor = Color.Gray, // 未获得焦点时的边框颜色//disabledBorderColor = Color.Gray, //禁用时的边框颜色//errorBorderColor = Color.Red, // 错误时的边框颜色))// 项目描述输入框OutlinedTextField(value = itemDescription,onValueChange = { itemDescription = it },label = { Text("项目描述") },modifier = Modifier.fillMaxWidth().padding(1.dp),colors = OutlinedTextFieldDefaults.colors(focusedTextColor = Color.Black, // 获得焦点时的文本颜色unfocusedTextColor = Color.Black, // 未获得焦点时的文本颜色focusedLabelColor = Color.Blue, // 获得焦点时的标签颜色unfocusedLabelColor = Color.Black, // 未获得焦点时的标签颜色cursorColor = Color.Black, // 光标颜色focusedBorderColor = Color.Blue, // 获得焦点时的边框颜色unfocusedBorderColor = Color.Gray, // 未获得焦点时的边框颜色//disabledBorderColor = Color.Gray, //禁用时的边框颜色//errorBorderColor = Color.Red, // 错误时的边框颜色))// 添加项目按钮/*Button(onClick = {val newItem = Item(name = itemName, description = itemDescription)dbHelper.insertItem(newItem) // 插入新项目到数据库items.clear() // 清空列表items.addAll(dbHelper.getAllItems()) // 重新从数据库加载数据itemName = "" // 清空输入框itemDescription = "" // 清空输入框},colors = ButtonDefaults.buttonColors(containerColor = Color(0xFFADD8E6)),modifier = Modifier.fillMaxWidth()) {Text("添加项目")}*/Button(onClick = {val newItem = Item(name = itemName, description = itemDescription)dbHelper.insertItem(newItem) // 插入新项目到数据库items.clear() // 清空列表items.addAll(dbHelper.getAllItems()) // 重新从数据库加载数据itemName = "" // 清空输入框itemDescription = "" // 清空输入框},colors = ButtonDefaults.buttonColors(containerColor = buttonColor), // 使用动态的按钮颜色modifier = Modifier.fillMaxWidth(),interactionSource = interactionSource // 将 interactionSource 传递给 Button) {Text("添加项目")}// 显示/隐藏数据库按钮Button(onClick = {showDatabaseContent.value = !showDatabaseContent.value // 切换显示/隐藏状态},colors = ButtonDefaults.buttonColors(containerColor = Color(0xFFADD8E6)),) {Text("显示/隐藏 数据库")}// 根据 showDatabaseContent 的值决定是否显示数据库内容if (showDatabaseContent.value) {DatabaseContentScreen(dbHelper) // 显示数据库内容}/*LazyColumn(modifier = Modifier.padding(16.dp)) {items(items) { item ->ItemRow(item = item)}}*/}
}@Composable
fun ItemRow(item: Item) {Column(modifier = Modifier.padding(8.dp)) {Text(text = "Name: ${item.name}")Text(text = "Description: ${item.description}")}
}// 数据库内容屏幕 Composable
@Composable
fun DatabaseContentScreen(dbHelper: DatabaseHelper) {// 使用 remember 记住从数据库获取的数据，并转换为可变列表val items = remember { dbHelper.getAllItems().toMutableList() }// 记住当前选中的项目，初始为 nullvar selectedItem by remember { mutableStateOf<Item?>(null) }// 创建一个 LazyListState，用于控制 LazyColumn 的滚动val lazyListState = rememberLazyListState()Column(modifier = Modifier.padding(16.dp)) {// 删除按钮Button(onClick = {selectedItem?.let {dbHelper.deleteItem(it.id!!) // 从数据库删除items.remove(it) // 从列表中移除selectedItem = null // 清空选中项}},enabled = selectedItem != null, // 仅当有选中项时才启用colors = ButtonDefaults.buttonColors(containerColor = Color(0xFFADD8E6)),//modifier = Modifier.padding(top = 8.dp)) {Text("删除选中项")}// 表头Row(modifier = Modifier.fillMaxWidth().background(Color.LightGray)) {TableCell(text = "ID", weight = 0.1f, isHeader = true) // ID 列TableCell(text = "名称", weight = 0.4f, isHeader = true) // 名称列TableCell(text = "描述", weight = 0.5f, isHeader = true) // 描述列}// 表格行LazyColumn (state = lazyListState, // 将 LazyListState 绑定到 LazyColumn//reverseLayout = true // 设置反向布局，让列表从底部开始显示){items(items) { item ->val isSelected = selectedItem?.id == item.id // 判断当前行是否被选中Row(modifier = Modifier.fillMaxWidth().clickable { selectedItem = if (isSelected) null else item } // 点击行时切换选中状态.background(if (isSelected) Color.Cyan else Color.Transparent) // 根据选中状态改变背景色) {TableCell(text = item.id?.toString() ?: "", weight = 0.1f) // IDTableCell(text = item.name, weight = 0.4f) // 名称TableCell(text = item.description, weight = 0.5f) // 描述}}}// 使用 LaunchedEffect 在 items 改变时滚动到最底部LaunchedEffect(items) {if (items.isNotEmpty()) {//lazyListState.scrollToItem(0) // 滚动到索引为 0 的项目，因为是反向布局，所以是最后一条数据//lazyListState.scrollToItem(items.size - 1) // 滚动到最后一条数据lazyListState.scrollToItem(items.lastIndex) // 滚动到最后一项}}}
}@Composable
fun TableCell(text: String, weight: Float, isHeader: Boolean = false) {Text(text = text,modifier = Modifier.padding(8.dp),fontWeight = if (isHeader) FontWeight.Bold else FontWeight.Normal)
}fun printDatabase(dbHelper: DatabaseHelper) {val items = dbHelper.getAllItems()Log.d("DatabaseContent", "--- Database Content ---")for (item in items) {Log.d("DatabaseContent", "ID: ${item.id}, Name: ${item.name}, Description: ${item.description}")}Log.d("DatabaseContent", "--- End of Database Content ---")
}