文章概述

农业机械是现代农业的重要生产工具，但购买成本高昂。租赁农业机械是许多农民的经济选择，可以降低初期投入成本并提高机械利用率。农业机械租赁成本计算器通过综合分析租赁时间、机械类型、使用强度等多个因素，科学计算租赁总成本，帮助农民选择最经济的租赁方案。准确的成本计算可以帮助农民制定合理的生产计划和预算。

农业机械租赁成本计算器在实际应用中有广泛的用途。在成本预算中，需要准确计算租赁成本。在方案选择中，需要比较租赁和购买的经济性。在租赁管理中，需要追踪租赁费用和使用情况。在成本控制中，需要优化机械使用效率。在投资决策中，需要评估长期购买还是短期租赁的经济性。

本文将深入探讨如何在KMP（Kotlin Multiplatform）框架下实现一套完整的农业机械租赁成本计算器，并展示如何在OpenHarmony鸿蒙平台上进行跨端调用。我们将提供多种成本计算功能，包括租赁成本计算、购买对比、成本优化等，帮助农民科学管理机械成本。

工具功能详解

核心功能

功能1：租赁成本计算（Rental Cost Calculation）

根据机械类型、租赁时间、使用强度计算租赁总成本。这是成本计算的基础。

功能特点：

• 支持多种机械类型
• 基于时间计算租赁费
• 考虑使用强度影响
• 返回详细的成本明细

功能2：租赁与购买对比（Rental vs Purchase Comparison）

对比租赁和购买的经济性，帮助做出最优决策。

功能特点：

• 计算购买成本
• 计算租赁成本
• 分析成本差异
• 推荐最优方案

功能3：长期租赁优化（Long-term Rental Optimization）

分析长期租赁的成本优化方案。

功能特点：

• 支持多个租赁周期
• 计算累积成本
• 分析成本趋势
• 提供优化建议

功能4：机械使用效率分析（Equipment Utilization Analysis）

分析机械使用效率对成本的影响。

功能特点：

• 计算单位面积成本
• 分析使用效率
• 评估成本效益
• 提供改进建议

功能5：租赁方案推荐（Rental Plan Recommendation）

根据农民需求推荐最优的租赁方案。

功能特点：

• 分析多个方案
• 计算各方案成本
• 评估方案优劣
• 推荐最优方案

Kotlin实现

完整的Kotlin代码实现

/**
 * 农业机械租赁成本计算器 - KMP OpenHarmony
 * 提供农业机械租赁成本计算的多种功能
 */
object MachineryRentalUtils {
    
    // 机械日租金（元/天）
    private val machineryDailyRates = mapOf(
        "拖拉机" to 200.0,
        "收割机" to 300.0,
        "播种机" to 150.0,
        "旋耕机" to 100.0,
        "喷雾机" to 80.0,
        "打捆机" to 250.0
    )
    
    // 机械购买价格（元）
    private val machineryPrices = mapOf(
        "拖拉机" to 50000.0,
        "收割机" to 80000.0,
        "播种机" to 20000.0,
        "旋耕机" to 10000.0,
        "喷雾机" to 5000.0,
        "打捆机" to 30000.0
    )
    
    // 机械年维护成本（购买后）
    private val maintenanceCosts = mapOf(
        "拖拉机" to 3000.0,
        "收割机" to 5000.0,
        "播种机" to 1000.0,
        "旋耕机" to 800.0,
        "喷雾机" to 500.0,
        "打捆机" to 2000.0
    )
    
    /**
     * 功能1：租赁成本计算
     */
    fun calculateRentalCost(
        machinery: String,
        rentalDays: Int,
        usageIntensity: Double = 1.0
    ): Map<String, Any> {
        val calculation = mutableMapOf<String, Any>()
        val dailyRate = machineryDailyRates[machinery] ?: 100.0
        
        // 基础租赁费
        val baseCost = dailyRate * rentalDays
        
        // 使用强度调整（强度越高，成本越高）
        val intensityAdjustment = baseCost * (usageIntensity - 1.0) * 0.1
        
        // 保险费（租赁期间）
        val insuranceCost = baseCost * 0.05
        
        // 运输费
        val transportCost = 200.0
        
        val totalCost = baseCost + intensityAdjustment + insuranceCost + transportCost
        val dailyCost = totalCost / rentalDays
        
        calculation["机械类型"] = machinery
        calculation["租赁天数"] = "$rentalDays 天"
        calculation["日租金"] = String.format("%.0f 元/天", dailyRate)
        calculation["基础租赁费"] = String.format("%.0f 元", baseCost)
        calculation["强度调整费"] = String.format("%.0f 元", intensityAdjustment)
        calculation["保险费"] = String.format("%.0f 元", insuranceCost)
        calculation["运输费"] = String.format("%.0f 元", transportCost)
        calculation["总租赁成本"] = String.format("%.0f 元", totalCost)
        calculation["日均成本"] = String.format("%.0f 元/天", dailyCost)
        
        return calculation
    }
    
    /**
     * 功能2：租赁与购买对比
     */
    fun compareRentalVsPurchase(
        machinery: String,
        rentalDays: Int,
        yearsOfUse: Int = 5
    ): Map<String, Any> {
        val comparison = mutableMapOf<String, Any>()
        
        // 租赁成本
        val rentalCost = calculateRentalCost(machinery, rentalDays)
        val totalRentalCost = (rentalCost["总租赁成本"] as String).split(" ")[0].toDouble()
        
        // 购买成本
        val purchasePrice = machineryPrices[machinery] ?: 30000.0
        val maintenanceCost = (maintenanceCosts[machinery] ?: 1000.0) * yearsOfUse
        val depreciationRate = 0.15  // 年折旧率15%
        val residualValue = purchasePrice * Math.pow(1 - depreciationRate, yearsOfUse.toDouble())
        val totalPurchaseCost = purchasePrice + maintenanceCost - residualValue
        
        // 对比分析
        val costDifference = totalPurchaseCost - totalRentalCost
        val savingPercentage = if (totalPurchaseCost > 0) (costDifference / totalPurchaseCost) * 100 else 0.0
        
        comparison["机械类型"] = machinery
        comparison["租赁方案"] = String.format("%.0f 元", totalRentalCost)
        comparison["购买价格"] = String.format("%.0f 元", purchasePrice)
        comparison["维护成本"] = String.format("%.0f 元", maintenanceCost)
        comparison["残值"] = String.format("%.0f 元", residualValue)
        comparison["购买总成本"] = String.format("%.0f 元", totalPurchaseCost)
        comparison["成本差异"] = String.format("%.0f 元", costDifference)
        comparison["节省比例"] = String.format("%.1f%%", savingPercentage)
        comparison["推荐方案"] = if (totalRentalCost < totalPurchaseCost) "租赁" else "购买"
        
        return comparison
    }
    
    /**
     * 功能3：长期租赁优化
     */
    fun optimizeLongTermRental(
        machinery: String,
        rentalDays: Int,
        cycles: Int
    ): Map<String, Any> {
        val optimization = mutableMapOf<String, Any>()
        
        val singleCycleCost = calculateRentalCost(machinery, rentalDays)
        val singleCostValue = (singleCycleCost["总租赁成本"] as String).split(" ")[0].toDouble()
        
        // 多周期租赁
        val totalCost = singleCostValue * cycles
        
        // 长期租赁折扣（3个周期以上享受10%折扣）
        val discount = if (cycles >= 3) 0.1 else 0.0
        val discountedCost = totalCost * (1 - discount)
        
        // 年均成本
        val annualCost = discountedCost / (rentalDays * cycles / 365.0)
        
        optimization["机械类型"] = machinery
        optimization["单周期成本"] = String.format("%.0f 元", singleCostValue)
        optimization["租赁周期数"] = cycles
        optimization["原始总成本"] = String.format("%.0f 元", totalCost)
        optimization["长期折扣"] = String.format("%.0f%%", discount * 100)
        optimization["优化后总成本"] = String.format("%.0f 元", discountedCost)
        optimization["年均成本"] = String.format("%.0f 元", annualCost)
        optimization["成本节省"] = String.format("%.0f 元", totalCost - discountedCost)
        
        return optimization
    }
    
    /**
     * 功能4：机械使用效率分析
     */
    fun analyzeUtilizationEfficiency(
        machinery: String,
        rentalDays: Int,
        cultivatedArea: Double
    ): Map<String, Any> {
        val analysis = mutableMapOf<String, Any>()
        
        val rentalCost = calculateRentalCost(machinery, rentalDays)
        val totalCost = (rentalCost["总租赁成本"] as String).split(" ")[0].toDouble()
        
        // 单位面积成本
        val costPerArea = totalCost / cultivatedArea
        
        // 使用效率评估
        val standardArea = when (machinery) {
            "拖拉机" to 100.0,
            "收割机" to 80.0,
            "播种机" to 120.0,
            "旋耕机" to 150.0,
            "喷雾机" to 200.0,
            "打捆机" to 60.0
        }.let { it[machinery] ?: 100.0 }
        
        val efficiency = (cultivatedArea / standardArea) * 100
        val efficiencyRating = when {
            efficiency >= 100 -> "优秀"
            efficiency >= 80 -> "良好"
            efficiency >= 60 -> "一般"
            else -> "较差"
        }
        
        analysis["机械类型"] = machinery
        analysis["租赁天数"] = "$rentalDays 天"
        analysis["种植面积"] = String.format("%.0f 亩", cultivatedArea)
        analysis["总租赁成本"] = String.format("%.0f 元", totalCost)
        analysis["单位面积成本"] = String.format("%.1f 元/亩", costPerArea)
        analysis["标准面积"] = String.format("%.0f 亩", standardArea)
        analysis["使用效率"] = String.format("%.0f%%", efficiency)
        analysis["效率评级"] = efficiencyRating
        
        return analysis
    }
    
    /**
     * 功能5：租赁方案推荐
     */
    fun recommendRentalPlan(
        machinery: String,
        cultivatedArea: Double,
        budget: Double
    ): Map<String, Any> {
        val recommendation = mutableMapOf<String, Any>()
        
        val dailyRate = machineryDailyRates[machinery] ?: 100.0
        
        // 计算可租赁天数
        val maxRentalDays = (budget / (dailyRate * 1.15)).toInt()  // 1.15是成本系数
        
        // 标准使用天数
        val standardDays = when (machinery) {
            "拖拉机" to 30,
            "收割机" to 20,
            "播种机" to 15,
            "旋耕机" to 10,
            "喷雾机" to 25,
            "打捆机" to 15
        }.let { it[machinery] ?: 20 }
        
        // 推荐方案
        val recommendedDays = Math.min(maxRentalDays, standardDays)
        val recommendedCost = calculateRentalCost(machinery, recommendedDays)
        val totalCost = (recommendedCost["总租赁成本"] as String).split(" ")[0].toDouble()
        
        // 是否超预算
        val isWithinBudget = totalCost <= budget
        val budgetStatus = if (isWithinBudget) "符合预算" else "超出预算"
        
        recommendation["机械类型"] = machinery
        recommendation["种植面积"] = String.format("%.0f 亩", cultivatedArea)
        recommendation["预算"] = String.format("%.0f 元", budget)
        recommendation["推荐租赁天数"] = "$recommendedDays 天"
        recommendation["推荐成本"] = String.format("%.0f 元", totalCost)
        recommendation["预算状态"] = budgetStatus
        recommendation["预算余额"] = String.format("%.0f 元", budget - totalCost)
        recommendation["方案评价"] = if (isWithinBudget) "可行" else "需要调整"
        
        return recommendation
    }
    
    /**
     * 生成完整的租赁成本报告
     */
    fun generateCompleteReport(
        machinery: String,
        rentalDays: Int,
        cultivatedArea: Double,
        budget: Double
    ): Map<String, Any> {
        val report = mutableMapOf<String, Any>()
        
        // 租赁成本
        report["租赁成本"] = calculateRentalCost(machinery, rentalDays)
        
        // 租赁与购买对比
        report["成本对比"] = compareRentalVsPurchase(machinery, rentalDays)
        
        // 使用效率
        report["使用效率"] = analyzeUtilizationEfficiency(machinery, rentalDays, cultivatedArea)
        
        // 方案推荐
        report["方案推荐"] = recommendRentalPlan(machinery, cultivatedArea, budget)
        
        return report
    }
}

// 使用示例
fun main() {
    println("KMP OpenHarmony 农业机械租赁成本计算器演示\n")
    
    // 租赁成本
    println("=== 租赁成本计算 ===")
    val rental = MachineryRentalUtils.calculateRentalCost("拖拉机", 30)
    rental.forEach { (k, v) -> println("$k: $v") }
    println()
    
    // 租赁与购买对比
    println("=== 租赁与购买对比 ===")
    val comparison = MachineryRentalUtils.compareRentalVsPurchase("拖拉机", 30)
    comparison.forEach { (k, v) -> println("$k: $v") }
    println()
    
    // 使用效率
    println("=== 使用效率分析 ===")
    val efficiency = MachineryRentalUtils.analyzeUtilizationEfficiency("拖拉机", 30, 100.0)
    efficiency.forEach { (k, v) -> println("$k: $v") }
    println()
    
    // 方案推荐
    println("=== 租赁方案推荐 ===")
    val recommendation = MachineryRentalUtils.recommendRentalPlan("拖拉机", 100.0, 8000.0)
    recommendation.forEach { (k, v) -> println("$k: $v") }
}

Kotlin实现的详细说明

Kotlin实现提供了五个核心功能。租赁成本计算根据机械类型和租赁时间计算总成本。租赁与购买对比分析两种方案的经济性。长期租赁优化计算多个周期的成本和折扣。使用效率分析评估单位面积成本。方案推荐根据预算和需求推荐最优方案。

JavaScript实现

完整的JavaScript代码实现

/**
 * 农业机械租赁成本计算器 - JavaScript版本
 */
class MachineryRentalJS {
    static machineryDailyRates = {
        '拖拉机': 200.0,
        '收割机': 300.0,
        '播种机': 150.0,
        '旋耕机': 100.0,
        '喷雾机': 80.0,
        '打捆机': 250.0
    };
    
    static machineryPrices = {
        '拖拉机': 50000.0,
        '收割机': 80000.0,
        '播种机': 20000.0,
        '旋耕机': 10000.0,
        '喷雾机': 5000.0,
        '打捆机': 30000.0
    };
    
    static maintenanceCosts = {
        '拖拉机': 3000.0,
        '收割机': 5000.0,
        '播种机': 1000.0,
        '旋耕机': 800.0,
        '喷雾机': 500.0,
        '打捆机': 2000.0
    };
    
    /**
     * 功能1：租赁成本计算
     */
    static calculateRentalCost(machinery, rentalDays, usageIntensity = 1.0) {
        const calculation = {};
        const dailyRate = this.machineryDailyRates[machinery] || 100.0;
        
        const baseCost = dailyRate * rentalDays;
        const intensityAdjustment = baseCost * (usageIntensity - 1.0) * 0.1;
        const insuranceCost = baseCost * 0.05;
        const transportCost = 200.0;
        
        const totalCost = baseCost + intensityAdjustment + insuranceCost + transportCost;
        const dailyCost = totalCost / rentalDays;
        
        calculation['机械类型'] = machinery;
        calculation['租赁天数'] = rentalDays + ' 天';
        calculation['日租金'] = dailyRate.toFixed(0) + ' 元/天';
        calculation['基础租赁费'] = baseCost.toFixed(0) + ' 元';
        calculation['强度调整费'] = intensityAdjustment.toFixed(0) + ' 元';
        calculation['保险费'] = insuranceCost.toFixed(0) + ' 元';
        calculation['运输费'] = transportCost.toFixed(0) + ' 元';
        calculation['总租赁成本'] = totalCost.toFixed(0) + ' 元';
        calculation['日均成本'] = dailyCost.toFixed(0) + ' 元/天';
        
        return calculation;
    }
    
    /**
     * 功能2：租赁与购买对比
     */
    static compareRentalVsPurchase(machinery, rentalDays, yearsOfUse = 5) {
        const comparison = {};
        
        const rentalCost = this.calculateRentalCost(machinery, rentalDays);
        const totalRentalCost = parseFloat(rentalCost['总租赁成本']);
        
        const purchasePrice = this.machineryPrices[machinery] || 30000.0;
        const maintenanceCost = (this.maintenanceCosts[machinery] || 1000.0) * yearsOfUse;
        const depreciationRate = 0.15;
        const residualValue = purchasePrice * Math.pow(1 - depreciationRate, yearsOfUse);
        const totalPurchaseCost = purchasePrice + maintenanceCost - residualValue;
        
        const costDifference = totalPurchaseCost - totalRentalCost;
        const savingPercentage = totalPurchaseCost > 0 ? (costDifference / totalPurchaseCost) * 100 : 0;
        
        comparison['机械类型'] = machinery;
        comparison['租赁方案'] = totalRentalCost.toFixed(0) + ' 元';
        comparison['购买价格'] = purchasePrice.toFixed(0) + ' 元';
        comparison['维护成本'] = maintenanceCost.toFixed(0) + ' 元';
        comparison['残值'] = residualValue.toFixed(0) + ' 元';
        comparison['购买总成本'] = totalPurchaseCost.toFixed(0) + ' 元';
        comparison['成本差异'] = costDifference.toFixed(0) + ' 元';
        comparison['节省比例'] = savingPercentage.toFixed(1) + '%';
        comparison['推荐方案'] = totalRentalCost < totalPurchaseCost ? '租赁' : '购买';
        
        return comparison;
    }
    
    /**
     * 功能3：长期租赁优化
     */
    static optimizeLongTermRental(machinery, rentalDays, cycles) {
        const optimization = {};
        
        const singleCycleCost = this.calculateRentalCost(machinery, rentalDays);
        const singleCostValue = parseFloat(singleCycleCost['总租赁成本']);
        
        const totalCost = singleCostValue * cycles;
        const discount = cycles >= 3 ? 0.1 : 0;
        const discountedCost = totalCost * (1 - discount);
        const annualCost = discountedCost / (rentalDays * cycles / 365.0);
        
        optimization['机械类型'] = machinery;
        optimization['单周期成本'] = singleCostValue.toFixed(0) + ' 元';
        optimization['租赁周期数'] = cycles;
        optimization['原始总成本'] = totalCost.toFixed(0) + ' 元';
        optimization['长期折扣'] = (discount * 100).toFixed(0) + '%';
        optimization['优化后总成本'] = discountedCost.toFixed(0) + ' 元';
        optimization['年均成本'] = annualCost.toFixed(0) + ' 元';
        optimization['成本节省'] = (totalCost - discountedCost).toFixed(0) + ' 元';
        
        return optimization;
    }
    
    /**
     * 功能4：机械使用效率分析
     */
    static analyzeUtilizationEfficiency(machinery, rentalDays, cultivatedArea) {
        const analysis = {};
        
        const rentalCost = this.calculateRentalCost(machinery, rentalDays);
        const totalCost = parseFloat(rentalCost['总租赁成本']);
        
        const costPerArea = totalCost / cultivatedArea;
        
        const standardAreas = {
            '拖拉机': 100.0,
            '收割机': 80.0,
            '播种机': 120.0,
            '旋耕机': 150.0,
            '喷雾机': 200.0,
            '打捆机': 60.0
        };
        
        const standardArea = standardAreas[machinery] || 100.0;
        const efficiency = (cultivatedArea / standardArea) * 100;
        
        let efficiencyRating;
        if (efficiency >= 100) efficiencyRating = '优秀';
        else if (efficiency >= 80) efficiencyRating = '良好';
        else if (efficiency >= 60) efficiencyRating = '一般';
        else efficiencyRating = '较差';
        
        analysis['机械类型'] = machinery;
        analysis['租赁天数'] = rentalDays + ' 天';
        analysis['种植面积'] = cultivatedArea.toFixed(0) + ' 亩';
        analysis['总租赁成本'] = totalCost.toFixed(0) + ' 元';
        analysis['单位面积成本'] = costPerArea.toFixed(1) + ' 元/亩';
        analysis['标准面积'] = standardArea.toFixed(0) + ' 亩';
        analysis['使用效率'] = efficiency.toFixed(0) + '%';
        analysis['效率评级'] = efficiencyRating;
        
        return analysis;
    }
    
    /**
     * 功能5：租赁方案推荐
     */
    static recommendRentalPlan(machinery, cultivatedArea, budget) {
        const recommendation = {};
        
        const dailyRate = this.machineryDailyRates[machinery] || 100.0;
        const maxRentalDays = Math.floor(budget / (dailyRate * 1.15));
        
        const standardDays = {
            '拖拉机': 30,
            '收割机': 20,
            '播种机': 15,
            '旋耕机': 10,
            '喷雾机': 25,
            '打捆机': 15
        };
        
        const standardDay = standardDays[machinery] || 20;
        const recommendedDays = Math.min(maxRentalDays, standardDay);
        const recommendedCost = this.calculateRentalCost(machinery, recommendedDays);
        const totalCost = parseFloat(recommendedCost['总租赁成本']);
        
        const isWithinBudget = totalCost <= budget;
        const budgetStatus = isWithinBudget ? '符合预算' : '超出预算';
        
        recommendation['机械类型'] = machinery;
        recommendation['种植面积'] = cultivatedArea.toFixed(0) + ' 亩';
        recommendation['预算'] = budget.toFixed(0) + ' 元';
        recommendation['推荐租赁天数'] = recommendedDays + ' 天';
        recommendation['推荐成本'] = totalCost.toFixed(0) + ' 元';
        recommendation['预算状态'] = budgetStatus;
        recommendation['预算余额'] = (budget - totalCost).toFixed(0) + ' 元';
        recommendation['方案评价'] = isWithinBudget ? '可行' : '需要调整';
        
        return recommendation;
    }
    
    /**
     * 生成完整的租赁成本报告
     */
    static generateCompleteReport(machinery, rentalDays, cultivatedArea, budget) {
        const report = {};
        
        report['租赁成本'] = this.calculateRentalCost(machinery, rentalDays);
        report['成本对比'] = this.compareRentalVsPurchase(machinery, rentalDays);
        report['使用效率'] = this.analyzeUtilizationEfficiency(machinery, rentalDays, cultivatedArea);
        report['方案推荐'] = this.recommendRentalPlan(machinery, cultivatedArea, budget);
        
        return report;
    }
}

// 导出供Node.js使用
if (typeof module !== 'undefined' && module.exports) {
    module.exports = MachineryRentalJS;
}

JavaScript实现的详细说明

JavaScript版本充分利用了JavaScript的对象和计算功能。租赁成本计算基于日租金和多个成本项目。租赁与购买对比分析两种方案的经济性。长期租赁优化计算折扣和年均成本。使用效率分析评估单位面积成本。方案推荐根据预算推荐最优租赁天数。

ArkTS调用实现

完整的ArkTS代码实现

/**
 * 农业机械租赁成本计算器 - ArkTS版本（OpenHarmony鸿蒙）
 */
import { webview } from '@kit.ArkWeb';
import { common } from '@kit.AbilityKit';

@Entry
@Component
struct MachineryRentalPage {
    @State machinery: string = '拖拉机';
    @State rentalDays: string = '30';
    @State cultivatedArea: string = '100';
    @State budget: string = '8000';
    @State result: string = '';
    @State selectedTool: string = '完整报告';
    @State isLoading: boolean = false;
    @State allResults: string = '';
    
    private machineryDailyRates: Record<string, number> = {
        '拖拉机': 200.0,
        '收割机': 300.0,
        '播种机': 150.0,
        '旋耕机': 100.0,
        '喷雾机': 80.0,
        '打捆机': 250.0
    };
    
    private machineryPrices: Record<string, number> = {
        '拖拉机': 50000.0,
        '收割机': 80000.0,
        '播种机': 20000.0,
        '旋耕机': 10000.0,
        '喷雾机': 5000.0,
        '打捆机': 30000.0
    };
    
    private maintenanceCosts: Record<string, number> = {
        '拖拉机': 3000.0,
        '收割机': 5000.0,
        '播种机': 1000.0,
        '旋耕机': 800.0,
        '喷雾机': 500.0,
        '打捆机': 2000.0
    };
    
    webviewController: webview.WebviewController = new webview.WebviewController();
    
    calculateRentalCost(machinery: string, rentalDays: number): string {
        const dailyRate = this.machineryDailyRates[machinery] || 100.0;
        const baseCost = dailyRate * rentalDays;
        const insuranceCost = baseCost * 0.05;
        const transportCost = 200.0;
        const totalCost = baseCost + insuranceCost + transportCost;
        const dailyCost = totalCost / rentalDays;
        
        let result = `租赁成本计算:\n`;
        result += `机械类型: ${machinery}\n`;
        result += `租赁天数: ${rentalDays} 天\n`;
        result += `日租金: ${dailyRate.toFixed(0)} 元/天\n`;
        result += `基础租赁费: ${baseCost.toFixed(0)} 元\n`;
        result += `保险费: ${insuranceCost.toFixed(0)} 元\n`;
        result += `运输费: ${transportCost.toFixed(0)} 元\n`;
        result += `总租赁成本: ${totalCost.toFixed(0)} 元\n`;
        result += `日均成本: ${dailyCost.toFixed(0)} 元/天`;
        
        return result;
    }
    
    compareRentalVsPurchase(machinery: string, rentalDays: number): string {
        const dailyRate = this.machineryDailyRates[machinery] || 100.0;
        const baseCost = dailyRate * rentalDays;
        const insuranceCost = baseCost * 0.05;
        const transportCost = 200.0;
        const totalRentalCost = baseCost + insuranceCost + transportCost;
        
        const purchasePrice = this.machineryPrices[machinery] || 30000.0;
        const maintenanceCost = (this.maintenanceCosts[machinery] || 1000.0) * 5;
        const depreciationRate = 0.15;
        const residualValue = purchasePrice * Math.pow(1 - depreciationRate, 5);
        const totalPurchaseCost = purchasePrice + maintenanceCost - residualValue;
        
        const costDifference = totalPurchaseCost - totalRentalCost;
        const savingPercentage = totalPurchaseCost > 0 ? (costDifference / totalPurchaseCost) * 100 : 0;
        
        let result = `租赁与购买对比:\n`;
        result += `机械类型: ${machinery}\n`;
        result += `租赁方案: ${totalRentalCost.toFixed(0)} 元\n`;
        result += `购买价格: ${purchasePrice.toFixed(0)} 元\n`;
        result += `维护成本: ${maintenanceCost.toFixed(0)} 元\n`;
        result += `残值: ${residualValue.toFixed(0)} 元\n`;
        result += `购买总成本: ${totalPurchaseCost.toFixed(0)} 元\n`;
        result += `成本差异: ${costDifference.toFixed(0)} 元\n`;
        result += `节省比例: ${savingPercentage.toFixed(1)}%\n`;
        result += `推荐方案: ${totalRentalCost < totalPurchaseCost ? '租赁' : '购买'}`;
        
        return result;
    }
    
    analyzeUtilizationEfficiency(machinery: string, rentalDays: number, cultivatedArea: number): string {
        const dailyRate = this.machineryDailyRates[machinery] || 100.0;
        const baseCost = dailyRate * rentalDays;
        const insuranceCost = baseCost * 0.05;
        const transportCost = 200.0;
        const totalCost = baseCost + insuranceCost + transportCost;
        
        const costPerArea = totalCost / cultivatedArea;
        
        const standardAreas: Record<string, number> = {
            '拖拉机': 100.0,
            '收割机': 80.0,
            '播种机': 120.0,
            '旋耕机': 150.0,
            '喷雾机': 200.0,
            '打捆机': 60.0
        };
        
        const standardArea = standardAreas[machinery] || 100.0;
        const efficiency = (cultivatedArea / standardArea) * 100;
        
        let efficiencyRating;
        if (efficiency >= 100) efficiencyRating = '优秀';
        else if (efficiency >= 80) efficiencyRating = '良好';
        else if (efficiency >= 60) efficiencyRating = '一般';
        else efficiencyRating = '较差';
        
        let result = `使用效率分析:\n`;
        result += `机械类型: ${machinery}\n`;
        result += `租赁天数: ${rentalDays} 天\n`;
        result += `种植面积: ${cultivatedArea.toFixed(0)} 亩\n`;
        result += `总租赁成本: ${totalCost.toFixed(0)} 元\n`;
        result += `单位面积成本: ${costPerArea.toFixed(1)} 元/亩\n`;
        result += `标准面积: ${standardArea.toFixed(0)} 亩\n`;
        result += `使用效率: ${efficiency.toFixed(0)}%\n`;
        result += `效率评级: ${efficiencyRating}`;
        
        return result;
    }
    
    recommendRentalPlan(machinery: string, cultivatedArea: number, budget: number): string {
        const dailyRate = this.machineryDailyRates[machinery] || 100.0;
        const maxRentalDays = Math.floor(budget / (dailyRate * 1.15));
        
        const standardDays: Record<string, number> = {
            '拖拉机': 30,
            '收割机': 20,
            '播种机': 15,
            '旋耕机': 10,
            '喷雾机': 25,
            '打捆机': 15
        };
        
        const standardDay = standardDays[machinery] || 20;
        const recommendedDays = Math.min(maxRentalDays, standardDay);
        
        const baseCost = dailyRate * recommendedDays;
        const insuranceCost = baseCost * 0.05;
        const transportCost = 200.0;
        const totalCost = baseCost + insuranceCost + transportCost;
        
        const isWithinBudget = totalCost <= budget;
        const budgetStatus = isWithinBudget ? '符合预算' : '超出预算';
        
        let result = `租赁方案推荐:\n`;
        result += `机械类型: ${machinery}\n`;
        result += `种植面积: ${cultivatedArea.toFixed(0)} 亩\n`;
        result += `预算: ${budget.toFixed(0)} 元\n`;
        result += `推荐租赁天数: ${recommendedDays} 天\n`;
        result += `推荐成本: ${totalCost.toFixed(0)} 元\n`;
        result += `预算状态: ${budgetStatus}\n`;
        result += `预算余额: ${(budget - totalCost).toFixed(0)} 元\n`;
        result += `方案评价: ${isWithinBudget ? '可行' : '需要调整'}`;
        
        return result;
    }
    
    generateCompleteReport(machinery: string, rentalDays: number, cultivatedArea: number, budget: number): string {
        let result = `=== 农业机械租赁成本完整报告 ===\n\n`;
        result += this.calculateRentalCost(machinery, rentalDays) + '\n\n';
        result += this.compareRentalVsPurchase(machinery, rentalDays) + '\n\n';
        result += this.analyzeUtilizationEfficiency(machinery, rentalDays, cultivatedArea) + '\n\n';
        result += this.recommendRentalPlan(machinery, cultivatedArea, budget);
        
        return result;
    }
    
    async executeCalculation() {
        this.isLoading = true;
        
        try {
            const days = parseInt(this.rentalDays);
            const area = parseFloat(this.cultivatedArea);
            const bud = parseFloat(this.budget);
            
            if (isNaN(days) || isNaN(area) || isNaN(bud) || days <= 0 || area <= 0 || bud <= 0) {
                this.result = '请输入有效的数值';
                this.isLoading = false;
                return;
            }
            
            let result = '';
            switch (this.selectedTool) {
                case '租赁成本':
                    result = this.calculateRentalCost(this.machinery, days);
                    break;
                case '成本对比':
                    result = this.compareRentalVsPurchase(this.machinery, days);
                    break;
                case '使用效率':
                    result = this.analyzeUtilizationEfficiency(this.machinery, days, area);
                    break;
                case '方案推荐':
                    result = this.recommendRentalPlan(this.machinery, area, bud);
                    break;
                case '完整报告':
                    result = this.generateCompleteReport(this.machinery, days, area, bud);
                    break;
            }
            
            this.result = result;
            this.allResults = this.generateCompleteReport(this.machinery, days, area, bud);
        } catch (error) {
            this.result = '执行错误：' + error;
        }
        
        this.isLoading = false;
    }
    
    build() {
        Column() {
            Row() {
                Text('农业机械租赁成本计算器')
                    .fontSize(24)
                    .fontWeight(FontWeight.Bold)
                    .fontColor(Color.White)
            }
            .width('100%')
            .height(60)
            .backgroundColor('#1565C0')
            .justifyContent(FlexAlign.Center)
            
            Scroll() {
                Column({ space: 12 }) {
                    Column() {
                        Text('机械类型:')
                            .fontSize(12)
                            .fontWeight(FontWeight.Bold)
                        Select([
                            { value: '拖拉机' },
                            { value: '收割机' },
                            { value: '播种机' },
                            { value: '旋耕机' },
                            { value: '喷雾机' },
                            { value: '打捆机' }
                        ])
                            .value(this.machinery)
                            .onSelect((index: number, value: string) => {
                                this.machinery = value;
                            })
                            .width('100%')
                    }
                    .width('100%')
                    .padding(10)
                    .backgroundColor('#E3F2FD')
                    .borderRadius(8)
                    
                    Column() {
                        Text('租赁天数:')
                            .fontSize(12)
                            .fontWeight(FontWeight.Bold)
                        TextInput({ placeholder: '请输入租赁天数' })
                            .value(this.rentalDays)
                            .onChange((value: string) => { this.rentalDays = value; })
                            .width('100%')
                            .height(50)
                            .padding(8)
                    }
                    .width('100%')
                    .padding(10)
                    .backgroundColor('#E3F2FD')
                    .borderRadius(8)
                    
                    Column() {
                        Text('种植面积 (亩):')
                            .fontSize(12)
                            .fontWeight(FontWeight.Bold)
                        TextInput({ placeholder: '请输入种植面积' })
                            .value(this.cultivatedArea)
                            .onChange((value: string) => { this.cultivatedArea = value; })
                            .width('100%')
                            .height(50)
                            .padding(8)
                    }
                    .width('100%')
                    .padding(10)
                    .backgroundColor('#E3F2FD')
                    .borderRadius(8)
                    
                    Column() {
                        Text('预算 (元):')
                            .fontSize(12)
                            .fontWeight(FontWeight.Bold)
                        TextInput({ placeholder: '请输入预算' })
                            .value(this.budget)
                            .onChange((value: string) => { this.budget = value; })
                            .width('100%')
                            .height(50)
                            .padding(8)
                    }
                    .width('100%')
                    .padding(10)
                    .backgroundColor('#E3F2FD')
                    .borderRadius(8)
                    
                    Column() {
                        Text('选择工具:')
                            .fontSize(12)
                            .fontWeight(FontWeight.Bold)
                        Select([
                            { value: '租赁成本' },
                            { value: '成本对比' },
                            { value: '使用效率' },
                            { value: '方案推荐' },
                            { value: '完整报告' }
                        ])
                            .value(this.selectedTool)
                            .onSelect((index: number, value: string) => {
                                this.selectedTool = value;
                            })
                            .width('100%')
                    }
                    .width('100%')
                    .padding(10)
                    .backgroundColor('#E3F2FD')
                    .borderRadius(8)
                    
                    if (this.result) {
                        Column() {
                            Text('结果:')
                                .fontSize(12)
                                .fontWeight(FontWeight.Bold)
                            Text(this.result)
                                .fontSize(11)
                                .width('100%')
                                .padding(8)
                                .backgroundColor('#F5F5F5')
                                .borderRadius(4)
                        }
                        .width('100%')
                        .padding(10)
                        .backgroundColor('#F5F5F5')
                        .borderRadius(8)
                    }
                    
                    if (this.allResults) {
                        Column() {
                            Text('完整报告:')
                                .fontSize(12)
                                .fontWeight(FontWeight.Bold)
                            Text(this.allResults)
                                .fontSize(11)
                                .width('100%')
                                .padding(8)
                                .backgroundColor('#E8F5E9')
                                .borderRadius(4)
                        }
                        .width('100%')
                        .padding(10)
                        .backgroundColor('#E8F5E9')
                        .borderRadius(8)
                    }
                    
                    Button('开始计算')
                        .width('100%')
                        .onClick(() => this.executeCalculation())
                        .enabled(!this.isLoading)
                    
                    if (this.isLoading) {
                        LoadingProgress()
                            .width(40)
                            .height(40)
                    }
                }
                .width('100%')
                .padding(16)
            }
            .layoutWeight(1)
        }
        .width('100%')
        .height('100%')
        .backgroundColor('#FAFAFA')
    }
}

ArkTS实现的详细说明

ArkTS版本为OpenHarmony鸿蒙平台提供了完整的用户界面。通过@State装饰器，我们可以管理应用的状态。这个实现包含了机械类型、租赁天数、种植面积、预算等输入功能，用户可以输入租赁数据，选择不同的计算工具，查看成本计算结果。

应用场景分析

1. 成本预算规划

农民需要准确计算租赁成本来制定预算。使用计算器可以获得详细的成本明细。

2. 租赁与购买决策

农民需要比较租赁和购买的经济性。使用计算器可以做出最优的投资决策。

3. 长期租赁管理

对于多个季节的租赁，需要计算累积成本和优化方案。使用计算器可以找到最经济的方案。

4. 使用效率优化

农民需要评估机械使用效率。使用计算器可以分析单位面积成本。

5. 方案推荐

根据预算和需求，需要推荐最优的租赁方案。使用计算器可以自动推荐方案。

性能优化建议

1. 实时价格更新

与市场价格数据集成，实时更新租赁价格。

2. 历史数据分析

存储历史租赁数据，分析成本趋势。

3. 多机械组合

支持多台机械的组合租赁计算。

4. 自动化报告

实现自动生成详细的租赁成本报告。

总结

农业机械租赁成本计算器是现代农业的重要工具。通过在KMP框架下实现这套工具，我们可以在多个平台上使用同一套代码，提高开发效率。这个工具提供了租赁成本计算、租赁与购买对比、长期租赁优化、使用效率分析和方案推荐等多种功能，可以满足大多数农民的机械租赁需求。

在OpenHarmony鸿蒙平台上，我们可以通过ArkTS调用这些工具，为农民提供完整的租赁成本计算体验。掌握这套工具，不仅能够帮助农民科学管理机械成本，更重要的是能够在实际项目中灵活应用，解决成本预算、投资决策等实际问题。