支付宝公积金模拟器，计算模型java版！

下载：http://lanzou.com.cn/i9c94f1ec

java
/**

• 公积金计算配置
• @author 阿里云开发者

• @date 2024-01-15
  /
  @Data
  @Builder
  public class HousingFundConfig {
  /** 缴存基数（元） /
  private BigDecimal baseAmount;

  /* 个人缴存比例（如0.12表示12%） /
  private BigDecimal personalRate;

  /* 单位缴存比例 /
  private BigDecimal companyRate;

  /* 上年结转利率（年化） /
  private BigDecimal lastYearRate;

  /* 当年缴存利率（年化） /
  private BigDecimal currentYearRate;

  /* 缴存基数上限 /
  private BigDecimal maxBaseAmount;

  /* 缴存基数下限 /
  private BigDecimal minBaseAmount;

  /* 所在城市 /
  private String city;

  /* 计息方式：月复利/年单利 /
  private String interestType;

  /* 默认配置（以上海为例） /
  public static HousingFundConfig defaultShanghai() {

   return HousingFundConfig.builder()
       .baseAmount(new BigDecimal("10000"))
       .personalRate(new BigDecimal("0.07"))
       .companyRate(new BigDecimal("0.07"))
       .lastYearRate(new BigDecimal("0.015"))
       .currentYearRate(new BigDecimal("0.0035"))
       .maxBaseAmount(new BigDecimal("28000"))
       .minBaseAmount(new BigDecimal("2480"))
       .city("上海")
       .interestType("monthly")
       .build();
  

  }
  }

  1. 账户实体类（Account）
     java
     /**
• 公积金账户

• @author 阿里云开发者
  /
  @Data
  @Builder
  public class HousingFundAccount {
  /** 账户ID /
  private String accountId;

  /* 用户姓名 /
  private String userName;

  /* 当前余额 /
  private BigDecimal currentBalance;

  /* 上年结转余额 /
  private BigDecimal lastYearBalance;

  /* 当年缴存余额 /
  private BigDecimal currentYearBalance;

  /* 账户状态 /
  private String status;

  /* 开户日期 /
  private LocalDate openDate;

  /* 最后计息日期 /
  private LocalDate lastInterestDate;
  }

  1. 核心计算引擎（Calculator）
     终于到了最关键的Calculator类！这里我采用了策略模式+工厂模式，让代码既清晰又易于扩展。

java
/**

• 公积金计算器核心引擎

• @author 阿里云开发者
  */
  @Service
  @Slf4j
  public class HousingFundCalculator {

  /* 缴存计算策略Map /
  private Map strategyMap;

  @PostConstruct
  public void init() {

   strategyMap = new HashMap<>();
   strategyMap.put("normal", new NormalContributionStrategy());
   strategyMap.put("supplement", new SupplementContributionStrategy());
   strategyMap.put("overseas", new OverseasContributionStrategy());
  

  }

  /**

  • 计算月度缴存额
  • @param config 公积金配置

  • @return 月缴存明细
    */
    public ContributionResult calculateMonthlyContribution(HousingFundConfig config) {
    // 校验缴存基数是否在上下限范围内
    BigDecimal validBase = validateBaseAmount(

     config.getBaseAmount(), 
     config.getMinBaseAmount(), 
     config.getMaxBaseAmount()
    

    );

    // 计算个人月缴存
    BigDecimal personalAmount = validBase

     .multiply(config.getPersonalRate())
     .setScale(2, RoundingMode.HALF_UP);
    

    // 计算单位月缴存
    BigDecimal companyAmount = validBase

     .multiply(config.getCompanyRate())
     .setScale(2, RoundingMode.HALF_UP);
    

    // 总缴存额
    BigDecimal totalAmount = personalAmount.add(companyAmount);

    return ContributionResult.builder()

     .baseAmount(validBase)
     .personalRate(config.getPersonalRate())
     .companyRate(config.getCompanyRate())
     .personalAmount(personalAmount)
     .companyAmount(companyAmount)
     .totalAmount(totalAmount)
     .build();
    

    }

    /**

  • 计算月利息
  • @param account 账户信息
  • @param config 配置

  • @return 当月利息
    */
    public BigDecimal calculateMonthlyInterest(HousingFundAccount account,

                                         HousingFundConfig config) {
    

    // 利息计算：上年结转部分按定期利率，当年缴存部分按活期利率
    BigDecimal lastYearInterest = account.getLastYearBalance()

     .multiply(config.getLastYearRate())
     .divide(new BigDecimal("12"), 2, RoundingMode.HALF_UP);
    

    BigDecimal currentYearInterest = account.getCurrentYearBalance()

     .multiply(config.getCurrentYearRate())
     .divide(new BigDecimal("12"), 2, RoundingMode.HALF_UP);
    

    return lastYearInterest.add(currentYearInterest);
    }

    /**

  • 模拟未来N个月的账户变化
  • @param account 当前账户
  • @param config 配置
  • @param months 模拟月数
  • @param monthlyExtract 每月提取额（0表示不提）

  • @return 预测结果列表
    */
    public List simulateFutureMonths(HousingFundAccount account,

                                                HousingFundConfig config,
                                                int months,
                                                BigDecimal monthlyExtract) {
    

    List snapshots = new ArrayList<>();

    // 创建当前账户副本
    HousingFundAccount current = copyAccount(account);
    LocalDate currentDate = LocalDate.now();

    // 计算月缴存额
    ContributionResult contribution = calculateMonthlyContribution(config);

    for (int i = 1; i <= months; i++) {

     // 计算当月利息（通常在6月30日计息，这里简化按月计息）
     BigDecimal interest = calculateMonthlyInterest(current, config);
    
     // 当月缴存
     BigDecimal monthlyContribution = contribution.getTotalAmount();
    
     // 当月提取
     BigDecimal extract = monthlyExtract != null ? monthlyExtract : BigDecimal.ZERO;
    
     // 更新余额
     BigDecimal newBalance = current.getCurrentBalance()
         .add(monthlyContribution)
         .add(interest)
         .subtract(extract);
    
     // 更新上年/当年余额（简化版：假设所有新增都算当年）
     current.setCurrentBalance(newBalance);
     current.setCurrentYearBalance(
         current.getCurrentYearBalance()
             .add(monthlyContribution)
             .add(interest)
             .subtract(extract)
     );
    
     // 记录快照
     AccountSnapshot snapshot = AccountSnapshot.builder()
         .month(currentDate.plusMonths(i))
         .balance(newBalance)
         .monthlyContribution(monthlyContribution)
         .monthlyInterest(interest)
         .monthlyExtract(extract)
         .build();
    
     snapshots.add(snapshot);
    

    }

    return snapshots;
    }

    /**

  • 校验缴存基数
    */
    private BigDecimal validateBaseAmount(BigDecimal base,

                                   BigDecimal min, 
                                   BigDecimal max) {
    

    if (base.compareTo(min) < 0) {

     log.warn("缴存基数{}低于下限{}，取下限值", base, min);
     return min;
    

    }
    if (base.compareTo(max) > 0) {

     log.warn("缴存基数{}高于上限{}，取上限值", base, max);
     return max;
    

    }
    return base;
    }

    private HousingFundAccount copyAccount(HousingFundAccount account) {
    // 深拷贝逻辑
    return HousingFundAccount.builder()

     .accountId(account.getAccountId())
     .userName(account.getUserName())
     .currentBalance(account.getCurrentBalance())
     .lastYearBalance(account.getLastYearBalance())
     .currentYearBalance(account.getCurrentYearBalance())
     .status(account.getStatus())
     .openDate(account.getOpenDate())
     .lastInterestDate(account.getLastInterestDate())
     .build();
    

    }
    }

    1. 结果展示类（DTO）
       java
       /**
• 月缴存结果
  */
  @Data
  @Builder
  public class ContributionResult {
  private BigDecimal baseAmount; // 实际缴存基数
  private BigDecimal personalRate; // 个人比例
  private BigDecimal companyRate; // 单位比例
  private BigDecimal personalAmount; // 个人缴存额
  private BigDecimal companyAmount; // 单位缴存额
  private BigDecimal totalAmount; // 总缴存额
  }

/**

• 账户快照
  */
  @Data
  @Builder
  public class AccountSnapshot {
  private LocalDate month; // 月份
  private BigDecimal balance; // 余额
  private BigDecimal monthlyContribution; // 月缴存
  private BigDecimal monthlyInterest; // 月利息
  private BigDecimal monthlyExtract; // 月提取
  }
  四、实战演练：来算算你的公积金！
  场景1：新入职程序员小张
  月薪：15000元

缴存比例：12%（单位和个人各12%）

当前余额：0元

上海缴存

java
@Test
public void testNewEmployee() {
// 初始化配置
HousingFundConfig config = HousingFundConfig.defaultShanghai();
config.setBaseAmount(new BigDecimal("15000"));
config.setPersonalRate(new BigDecimal("0.12"));
config.setCompanyRate(new BigDecimal("0.12"));

// 初始化账户
HousingFundAccount account = HousingFundAccount.builder()
    .accountId("001")
    .userName("小张")
    .currentBalance(BigDecimal.ZERO)
    .lastYearBalance(BigDecimal.ZERO)
    .currentYearBalance(BigDecimal.ZERO)
    .build();

// 创建计算器
HousingFundCalculator calculator = new HousingFundCalculator();

// 计算月缴存
ContributionResult contribution = calculator.calculateMonthlyContribution(config);
System.out.println("月缴存明细：");
System.out.println("个人缴存：" + contribution.getPersonalAmount() + "元");
System.out.println("单位缴存：" + contribution.getCompanyAmount() + "元");
System.out.println("月总缴存：" + contribution.getTotalAmount() + "元");

// 模拟12个月
List<AccountSnapshot> snapshots = calculator.simulateFutureMonths(
    account, config, 12, BigDecimal.ZERO
);

System.out.println("\n12个月后账户余额预测：");
AccountSnapshot last = snapshots.get(snapshots.size() - 1);
System.out.println("时间：" + last.getMonth());
System.out.println("余额：" + last.getBalance() + "元");
System.out.println("累计缴存：" + contribution.getTotalAmount()
    .multiply(new BigDecimal("12")) + "元");
System.out.println("累计利息：" + last.getBalance()
    .subtract(contribution.getTotalAmount().multiply(new BigDecimal("12"))));

}
运行结果：

text
月缴存明细：
个人缴存：1800.00元
单位缴存：1800.00元
月总缴存：3600.00元

12个月后账户余额预测：
时间：2025-01-15
余额：43458.32元
累计缴存：43200.00元
累计利息：258.32元
场景2：购房者老王
当前余额：20万

月缴存：3000元

计划每月提取2000元还贷

预测2年后余额

java
@Test
public void testHomeBuyer() {
HousingFundConfig config = HousingFundConfig.defaultShanghai();
config.setBaseAmount(new BigDecimal("12500")); // 对应3000月缴存
config.setPersonalRate(new BigDecimal("0.12"));
config.setCompanyRate(new BigDecimal("0.12"));

HousingFundAccount account = HousingFundAccount.builder()
    .accountId("002")
    .userName("老王")
    .currentBalance(new BigDecimal("200000"))
    .lastYearBalance(new BigDecimal("150000"))  // 假设15万是上年结转
    .currentYearBalance(new BigDecimal("50000"))
    .build();

HousingFundCalculator calculator = new HousingFundCalculator();

// 模拟24个月，每月提取2000
List<AccountSnapshot> snapshots = calculator.simulateFutureMonths(
    account, config, 24, new BigDecimal("2000")
);

System.out.println("24个月后账户情况：");
for (int i = 0; i < snapshots.size(); i += 6) { // 每6个月输出一次
    AccountSnapshot s = snapshots.get(i);
    System.out.println(s.getMonth() + "：余额 " + s.getBalance() + "元");
}

}
五、进阶优化：让计算更精准

1. 计息规则优化（真实银行算法）
   java
   /**

   • 精确计息器（按实际天数计算）
     */
     public class AccurateInterestCalculator {

     /**

     • 计算区间利息（按日计算）
     • @param balance 本金
     • @param rate 年利率
     • @param startDate 开始日期
     • @param endDate 结束日期
     • @return 利息
       */
       public BigDecimal calculateDailyInterest(BigDecimal balance,

                                         BigDecimal rate,
                                         LocalDate startDate,
                                         LocalDate endDate) {
       

       long days = ChronoUnit.DAYS.between(startDate, endDate);
       return balance

        .multiply(rate)
        .multiply(new BigDecimal(days))
        .divide(new BigDecimal("365"), 8, RoundingMode.HALF_UP)
        .setScale(2, RoundingMode.HALF_UP);
       

       }

     /**

     • 年度结息（每年6月30日）
       */
       public void annualSettlement(HousingFundAccount account,

                             HousingFundConfig config,
                             LocalDate settlementDate) {
       

       // 上年结转部分：按定期利率计算全年
       BigDecimal lastYearInterest = calculateDailyInterest(

        account.getLastYearBalance(),
        config.getLastYearRate(),
        settlementDate.minusYears(1),
        settlementDate
       

       );

       // 当年缴存部分：分段计息
       BigDecimal currentYearInterest = calculateCurrentYearInterest(

        account, config, settlementDate
       

       );

       // 结转：当年余额转入上年余额
       account.setLastYearBalance(

        account.getLastYearBalance()
            .add(account.getCurrentYearBalance())
            .add(lastYearInterest)
            .add(currentYearInterest)
       

       );
       account.setCurrentYearBalance(BigDecimal.ZERO);
       account.setLastInterestDate(settlementDate);
       }
       }

2. 多城市支持（配置化）
   java
   @Component
   public class CityConfigManager {

   private Map cityConfigMap;

   @PostConstruct
   public void loadConfigs() {

    cityConfigMap = new HashMap<>();
   
    // 上海配置
    cityConfigMap.put("上海", HousingFundConfig.builder()
        .maxBaseAmount(new BigDecimal("28000"))
        .minBaseAmount(new BigDecimal("2480"))
        .lastYearRate(new BigDecimal("0.015"))
        .currentYearRate(new BigDecimal("0.0035"))
        .build());
   
    // 北京配置
    cityConfigMap.put("北京", HousingFundConfig.builder()
        .maxBaseAmount(new BigDecimal("28221"))
        .minBaseAmount(new BigDecimal("2320"))
        .lastYearRate(new BigDecimal("0.015"))
        .currentYearRate(new BigDecimal("0.0035"))
        .build());
   
    // 深圳配置
    cityConfigMap.put("深圳", HousingFundConfig.builder()
        .maxBaseAmount(new BigDecimal("34860"))
        .minBaseAmount(new BigDecimal("2200"))
        .lastYearRate(new BigDecimal("0.015"))
        .currentYearRate(new BigDecimal("0.0035"))
        .build());
   

   }

   public HousingFundConfig getConfigByCity(String city) {

    HousingFundConfig config = cityConfigMap.get(city);
    if (config == null) {
        throw new IllegalArgumentException("不支持的城市：" + city);
    }
    return config;
   

   }
   }
   六、API封装：对外提供REST服务
   java
   @RestController
   @RequestMapping("/api/housing-fund")
   @Api(tags = "公积金计算服务")
   public class HousingFundController {

   @Autowired
   private HousingFundCalculator calculator;

   @Autowired
   private CityConfigManager configManager;

   @PostMapping("/simulate")
   @ApiOperation("模拟公积金账户变化")
   public Result simulate(@RequestBody SimulateRequest request) {

    // 获取城市配置
    HousingFundConfig config = configManager.getConfigByCity(request.getCity());
    config.setBaseAmount(request.getBaseAmount());
    config.setPersonalRate(request.getPersonalRate());
    config.setCompanyRate(request.getCompanyRate());
   
    // 构建账户
    HousingFundAccount account = buildAccount(request);
   
    // 模拟计算
    List<AccountSnapshot> snapshots = calculator.simulateFutureMonths(
        account, config, request.getMonths(), request.getMonthlyExtract()
    );
   
    // 构建响应
    SimulateResponse response = SimulateResponse.builder()
        .snapshots(snapshots)
        .totalContribution(calculateTotalContribution(snapshots))
        .totalInterest(calculateTotalInterest(snapshots))
        .build();
   
    return Result.success(response);
   

   }

   @GetMapping("/calculator")
   @ApiOperation("在线计算器页面")
   public ModelAndView calculatorPage() {

    ModelAndView mv = new ModelAndView("housing-fund-calculator");
    mv.addObject("cities", configManager.getSupportedCities());
    return mv;
   

   }
   }
   七、前端页面：Vue3简单实现
   vue

   
   
   
   

   🏠 公积金模拟计算器

   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   开始模拟
   重置
   
   
   
   

   
   

   模拟结果

   
   
   
   
   

   期末余额

   
   

   { { result.finalBalance }} 元

   
   
   
   
   
   

   累计缴存

   
   

   { { result.totalContribution }} 元

   
   
   
   
   
   

   累计利息

   
   

   { { result.totalInterest }} 元