代码设计之多渠道支付

支付网关中需要接入多个支付渠道，如cybs、fortumo、amx，其中cybs为信用卡支付，其他两个为运营商支付。

不管使用那种支付渠道，支付流程都是类似的。显而易见可以使用模板方法。首先定义一个模板类，支付流程中各支付渠道通用的方法放在模板类中，特异于各个支付渠道的方法作为抽象方法，由子类实现。

如下图所示：

其中AbstractPaymentService为模板类，其他三个为各支付渠道实现子类。

模板类--AbstractPaymentService伪代码如下所示：

protected final Logger logger = LoggerFactory.getLogger(AbstractPaymentService.class);
public PayResultDTO pay(PayOrderDTO dto){

logger.info("Entering pay, and the dto is {}", dto);

//将DTO转为Entity(数据库实体)

PayOrder payOrder = convertDTOToEntity(dto);

//落地支付单

insertPayOrder(payOrder);

//去支付 抽象方法 由各个支付渠道自己去实现

return doPay(dto);

}

protected abstract PayResultDTO doPay(PayOrderDTO dto) ;

private void insertPayOrder(PayOrder payOrder) {

// do something here...

}

private PayOrder convertDTOToEntity(PayOrderDTO dto) {

//do something here...

return null;

}

Cybs支付渠道实现子类–CybsPaymentService伪代码如下：

@Override
 protected PayResultDTO doPay(PayOrderDTO dto) {
     //使用cybs 第一次支付需要特殊处理
     if(dto.isFirstPay())
         return doFirstPay();
     else
         return doNormalPay();
 }
 private PayResultDTO doNormalPay() {
     //do smething here...
     return result;
 }
 private PayResultDTO doFirstPay() {
     //do smething here...
     return result;
 }

其他两个支付渠道实现类类似，只要实现doPay方法即可。比如Amx以HttpClient方式调用Amx Server的Http接口发起支付并同步等待返回。

若这时需要接入一个新的支付渠道，如Paypal，只需定义一个PaypalPaymentService继承模板类–AbstractPaymentService,同时实现doPay方法即可。

接着再定义一个支付门面类，方便客户端（交易系统）调用支付方法，即客户端无需关心是哪种支付渠道，只须调用pay方法即可。支付门面代码如下所示：

@Service
public class PaymentFacadeService {
    @Autowired
    private CybsPaymentService cybsPaymentService;
    @Autowired
    private FortumoPaymentService fortumoPaymentService;
    @Autowired
    private AmxPaymentService amxPaymentService;
<span class="hljs-function"><span class="hljs-keyword">public</span> PayResultDTO <span class="hljs-title">pay</span><span class="hljs-params">(PayOrderDTO dto)</span> </span>{
    String payChannel = dto.getPayChannel();
    <span class="hljs-keyword">if</span> (payChannel.equalsIgnoreCase(<span class="hljs-string">"cybs"</span>))
        <span class="hljs-keyword">return</span> cybsPaymentService.pay(dto);
    <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (payChannel.equalsIgnoreCase(<span class="hljs-string">"fortumo"</span>))
        <span class="hljs-keyword">return</span> fortumoPaymentService.pay(dto);
    <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (payChannel.equalsIgnoreCase(<span class="hljs-string">"amx"</span>))
        <span class="hljs-keyword">return</span> amxPaymentService.pay(dto);
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">null</span>;
}

}

门面类应该有更优雅的实现方式，即不用在门面类的成员变量中全部罗列出所有的支付渠道的实现类。

这时客户端调用支付方法伪代码示例为：

@Autowired
private PaymentFacadeService paymentServcie;
public MyResultDTO pay(...){

//构造payOrderDTO

PayOrderDTO dto = new PayOrderDTO();

//填充属性

//...

PayResultDTO resultDTO = paymentServcie.pay(dto);

//do something with resultDTO

return myResult;

}

支付门面设计方案二：

public class PaymentFacadeService2 {
    private Map<String,AbstractPaymentService> channelServiceMap;
<span class="hljs-function"><span class="hljs-keyword">public</span> PayResultDTO <span class="hljs-title">pay</span>(<span class="hljs-params">PayOrderDTO dto</span>) </span>{
    String payChannel = dto.getPayChannel();

    <span class="hljs-keyword">return</span> channelServiceMap.<span class="hljs-keyword">get</span>(payChannel).pay(dto);
}
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setChannelServiceMap</span>(<span class="hljs-params">Map&lt;String, AbstractPaymentService&gt; serviceMap</span>) </span>{
    <span class="hljs-keyword">this</span>.channelServiceMap = serviceMap;
}

}

spring 配置：

<bean id="paymentFacadeService2"
        class="com.tcl.gateway.service.refactoring.PaymentFacadeService2">
        <property name="channelServiceMap">
            <map>
                <entry key="cybs">
                    <bean class="com.tcl.gateway.service.refactoring.CybsPaymentService"></bean>
                </entry>
                <entry key="fortumo">
                    <bean class="com.tcl.gateway.service.refactoring.FortumoPaymentService"></bean>
                </entry>
                <entry key="amx">
                    <bean class="com.tcl.gateway.service.refactoring.AmxPaymentService"></bean>
                </entry>
            </map>
        </property>
    </bean>