前端开发者的 Kotlin 之旅：反射解析

// JavaScript 中的"反射"操作
const user = { name: 'Alice', age: 25, email: 'alice@example.com' };

// 1. 检查对象结构
console.log(Object.keys(user)); // ['name', 'age', 'email']
console.log(typeof user.name);  // 'string'

// 2. 动态访问属性
const propertyName = 'email';
console.log(user[propertyName]); // 'alice@example.com'

// 3. 动态调用方法
const methodName = 'toString';
console.log(user[methodName]()); // '[object Object]'

import kotlin.reflect.*
import kotlin.reflect.full.*

data class User(val name: String, val age: Int)

fun basicClassInfo() {
    val userClass = User::class
    println("类名: ${userClass.simpleName}")
    println("属性数量: ${userClass.memberProperties.size}")
}

const user = { name: 'Alice', age: 25 };
console.log(user.constructor.name); // 'Object'

fun dynamicPropertyAccess() {
    val user = User("Alice", 25)
    val nameProperty = User::class.memberProperties.find { it.name == "name" }
    val nameValue = nameProperty?.get(user)
    println("动态获取 name: $nameValue")
}

const user = { name: 'Alice', age: 25 };
console.log(user['name']); // 'Alice'

data class UserProfile(val name: String, var isActive: Boolean = true)

fun propertyReferenceDemo() {
    val user = UserProfile("Alice", true)
    val nameRef = UserProfile::name
    val isActiveRef = UserProfile::isActive
    
    println("姓名: ${nameRef.get(user)}")
    isActiveRef.set(user, false)
    println("修改后状态: ${user.isActive}")
}

const user: { name: string; isActive: boolean } = { name: 'Alice', isActive: true };
const propertyName: keyof typeof user = 'name';
console.log(user[propertyName]); // TypeScript 类型安全

@Target(AnnotationTarget.PROPERTY)
@Retention(AnnotationRetention.RUNTIME)
annotation class Required

data class UserForm(@Required val name: String, val age: Int?)

fun basicAnnotationDemo() {
    UserForm::class.memberProperties.forEach { property ->
        if (property.hasAnnotation<Required>()) {
            println("${property.name} 是必填字段")
        }
    }
}

function Required(target: any, propertyKey: string) {
    Reflect.defineMetadata('required', true, target, propertyKey);
}

data class AppConfig(val apiUrl: String, val timeout: Int)

fun processConfig() {
    val configData = mapOf("apiUrl" to "https://api.example.com", "timeout" to 5000)
    val constructor = AppConfig::class.primaryConstructor!!
    val args = constructor.parameters.associateWith { configData[it.name] }
    val config = constructor.callBy(args)
    println("配置: $config")
}

// 类似 process.env 的动态配置加载
const config = { apiUrl: process.env.API_URL, timeout: 5000 };

fun validateUserData() {
    val userData = mapOf("name" to "", "email" to "invalid")
    val errors = mutableListOf<String>()
    
    UserForm::class.memberProperties.forEach { property ->
        val value = userData[property.name]
        if (property.hasAnnotation<Required>() && (value == null || value == "")) {
            errors.add("${property.name} 不能为空")
        }
    }
    
    println("验证错误: $errors")
}

function validateForm(data) {
    const errors = [];
    if (!data.name) errors.push('name 不能为空');
    return errors;
}

fun simpleObjectToString(obj: Any): String {
    val properties = obj::class.memberProperties
    val pairs = properties.map { "${it.name}: ${it.get(obj)}" }
    return "${obj::class.simpleName}(${pairs.joinToString(", ")})"
}

JSON.stringify(user); // JavaScript 的对象序列化

fun createObjectDynamically() {
    val constructor = User::class.primaryConstructor!!
    val user = constructor.call("Alice", 25)
    println("动态创建: $user")
}

function createUser(name, age) {
    return { name, age };
}