从宏观到代码：使用C4模型可视化软件架构的入门指南

@startuml
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Container.puml

title PayQuick - 系统上下文图

Person(customer, "个人客户", "使用应用程序转账和支付账单")
Person(merchant, "商户", "接收客户的付款")

System_Boundary(payquick, "PayQuick平台") {
    System(payquick_system, "PayQuick", "允许客户进行付款和转账")
}

System_Ext(bank_system, "银行网络", "处理跨行转账", $tags="external")
System_Ext(sms_gateway, "Twilio短信", "发送交易通知", $tags="external")
System_Ext(email_service, "SendGrid", "发送电子邮件收据", $tags="external")

Rel(customer, payquick_system, "转账、支付账单、查看交易")
Rel(merchant, payquick_system, "接收付款、发出退款")
Rel(payquick_system, bank_system, "通过", "API")
Rel(payquick_system, sms_gateway, "通过", "HTTPS")
Rel(payquick_system, email_service, "通过", "SMTP")

LAYOUT_WITH_LEGEND()
@enduml

@startuml
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Container.puml

title PayQuick - 容器图

Person(customer, "客户", "使用移动应用或网页界面")
Person(merchant, "商户", "使用网页控制台")

System_Boundary(payquick, "PayQuick 平台") {
    Container(mobile_app, "移动应用", "React Native, TypeScript", "为客户提供用户界面")
    Container(web_app, "Web 应用", "React, TypeScript", "提供管理员和商户控制台")
    
    Container_Boundary(api, "API 应用") {
        Container(api_gateway, "API 网关", "Node.js, Express", "处理路由、认证和限流")
        Container(payment_service, "支付服务", "Spring Boot, Java", "处理支付和转账")
        Container(notification_service, "通知服务", "Python, FastAPI", "发送短信和邮件通知")
    }
    
    ContainerDb(database, "数据库", "PostgreSQL", "存储用户账户、交易记录和余额")
    ContainerDb(cache, "缓存", "Redis", "存储会话数据和频繁访问的记录")
    ContainerQueue(queue, "消息队列", "RabbitMQ", "处理异步通知处理")
}

System_Ext(bank_api, "银行 API", "外部银行集成")
System_Ext(sms_provider, "Twilio 短信 API")

Rel(customer, mobile_app, "使用", "HTTPS")
Rel(merchant, web_app, "使用", "HTTPS")
Rel(mobile_app, api_gateway, "调用 API", "HTTPS/JSON")
Rel(web_app, api_gateway, "调用 API", "HTTPS/JSON")
Rel(api_gateway, payment_service, "将请求路由至", "gRPC")
Rel(api_gateway, notification_service, "将请求路由至", "gRPC")
Rel(payment_service, database, "读写数据", "JDBC")
Rel(payment_service, cache, "将频繁数据缓存至", "Redis 协议")
Rel(notification_service, queue, "发布事件至", "AMQP")
Rel(notification_service, sms_provider, "通过发送短信", "REST API")
Rel(payment_service, bank_api, "通过处理转账", "HTTPS")
@enduml

@startuml
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Component.puml

title PayQuick - 支付服务组件图

!define C4ShapeInRow 4
!define C4BoundaryInRow 1

Container_Boundary(payment_service, "支付服务") {
    Component(payment_controller, "支付控制器", "Spring REST 控制器", "处理传入的支付请求")
    Component(transaction_manager, "交易管理器", "Spring 服务", "协调支付工作流")
    Component(fraud_detector, "欺诈检测服务", "Spring 服务", "验证交易是否存在欺诈")
    Component(balance_calculator, "余额计算器", "Spring 服务", "计算并更新账户余额")
    Component(validation_service, "验证服务", "Spring 服务", "验证支付数据和业务规则")
    
    ComponentDb(transaction_repo, "交易仓库", "Spring Data JPA", "存储交易记录")
    ComponentDb(account_repo, "账户仓库", "Spring Data JPA", "管理账户数据")
    ComponentDb(fraud_repo, "欺诈规则仓库", "Spring Data JPA", "存储欺诈检测规则")
    
    Component(notification_client, "通知客户端", "Feign 客户端", "调用通知服务")
    Component(bank_client, "银行客户端", "Feign 客户端", "与外部银行 API 集成")
}

Rel(payment_controller, transaction_manager, "将支付请求转发给")
Rel(transaction_manager, fraud_detector, "使用...验证交易")
Rel(transaction_manager, validation_service, "使用...验证数据")
Rel(transaction_manager, balance_calculator, "通过...更新余额")
Rel(transaction_manager, transaction_repo, "将交易保存到")
Rel(balance_calculator, account_repo, "读取/写入账户数据到")
Rel(fraud_detector, fraud_repo, "根据规则进行检查")
Rel(transaction_manager, notification_client, "通过...发送通知")
Rel(transaction_manager, bank_client, "通过...处理外部转账")

@enduml

@startuml
title 欺诈检测服务 - 类图

class 欺诈检测服务 {
    - 欺诈规则仓库 fraudRepo
    - 交易仓库 txnRepo
    + checkFraud(txn: 交易): 欺诈结果
    - evaluateRules(txn: 交易): List<规则>
    - calculateRiskScore(txn: 交易): Double
    - isVelocityExceeded(userId: String): Boolean
}

class 欺诈结果 {
    + isBlocked: boolean
    + riskScore: double
    + blockedRules: List<String>
    + getRiskLevel(): 风险等级
}

class 欺诈规则 {
    + id: Long
    + ruleName: String
    + threshold: Double
    + isEnabled: boolean
    + evaluate(txn: 交易): boolean
}

class 交易 {
    + id: String
    + amount: BigDecimal
    + userId: String
    + timestamp: DateTime
    + merchantId: String
}

欺诈检测服务 --> 欺诈结果 : 返回
欺诈检测服务 --> 欺诈规则 : 使用
欺诈检测服务 --> 交易 : 验证
欺诈结果 ..> 欺诈规则 : 包含

@enduml