Android Studio 中使用 SQLite 数据库实现登录和注册

import android.content.ContentValues
import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
 
class UserDatabaseOpenHelper(context: Context) : SQLiteOpenHelper(context, "UserInfo.db", null, 1) {
 
    override fun onCreate(db: SQLiteDatabase) {
        val createTableUser = "CREATE TABLE IF NOT EXISTS User (" +
                "id INTEGER PRIMARY KEY AUTOINCREMENT, " +
                "username TEXT, " +
                "password TEXT)"
        db.execSQL(createTableUser)
    }
 
    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        // 这里可以执行数据库升级操作
    }
}
 
class UserDataBaseAdapter(context: Context) {
    private val database: SQLiteDatabase
    private val dbOpenHelper: UserDatabaseOpenHelper = UserDatabaseOpenHelper(context)
 
    init {
        database = dbOpenHelper.writableDatabase
    }
 
    fun register(username: String, password: String): Boolean {
        val contentValues = ContentValues()
        contentValues.put("username", username)
        contentValues.put("password", password)
        val result = database.insert("User", null, contentValues)
        return result != -1L
    }
 
    fun login(username: String, password: String): Boolean {
        val selectQuery = "SELECT * FROM User WHERE username = '$username' AND password = '$password'"
        val cursor = database.rawQuery(selectQuery, null)
        return cursor.moveToFirst()
    }
}

这段代码定义了一个UserDatabaseOpenHelper类，继承自SQLiteOpenHelper，用于创建和管理SQLite数据库。UserDataBaseAdapter类封装了注册和登录的方法，使用ContentValues存储用户数据，并通过SQLiteDatabase执行数据库操作。注意，在实际应用中，用户密码应该加密存储，以上代码为示例，未包含加密逻辑。