重构MQ处理架构：MVEL表达式和责任链设计模式应用实践

本文主要讲解了MVEL表达式和责任链设计模式相结合一起的消息处理解决方案设计、解耦消息处理节点以及方便代码维护扩展。通过“订单拆单消息”的接入作为具体实践案例，简要阐述了MVEL表达式和Apache Chain职责链设计模式应用场景。希望通过本文，读者可以对MVEL表达式和责任链模式相关概念有一定的认识，并且能够将它们应用到具体的业务场景之中，帮助大家在实际代码研发的时候，降低代码复杂度和提升代码的复用率。

【本文目录】

• 背景

• MVEL表达式

• 责任链设计模式

• 实践案例（订单MQ消息处理流程）

• 总结

public void handleMessage(String message) throws Exception {    CallerInfo callerInfo = Profiler.registerInfo(UmpKey.KEY_BD_DLOK_FLAG_GHOST_HANDLER, "xxx", false, true);    try {        DeliveredMessage msg = parseMessage(message);        if (null == msg) {            return;        }        String id = msg.getOrderId();        if (null == id) {            //监听到的订单消息 id不应为空            return;        }        String sendPay = msg.getSendPay();        //是否XXX        boolean isShop = CAR_O2O.equals(String.valueOf(sendPay.charAt(XXX)));        //是否是XXX        boolean isCar = CAR_ADDED_SERVICE.equals(String.valueOf(sendPay.charAt(XXX)));        String waybillSign = msg.getWaybillSign();        //是否是XX        boolean isSelf = SELF_ORDER.equals(String.valueOf(waybillSign.charAt(XXX)));
        long tid = System.nanoTime();        Long orderId = Long.parseLong(id);
        //监听到订单后，更改订单状态表中的订单状态        if (isCar && isSelf) {            verOrderCarService.updateVerOrderCarStatusByOrderId(tid, orderIdLong, UPDATE_PIN);        }        if (isShop && isCar) {            if (isSelf) {                // 若在新表ver_order_sms_car中存在发送模板1短信，否则，发送原短信（模板3）                List<VerOrderSmsCar> verOrderSmsCarList = verOrderSmsCarDao.getCarOrderListByOrderId(orderIdLong);                if (CollectionUtils.isEmpty(verOrderSmsCarList)) {                    dealTemplateThreeOrder(tid,orderId);                } else {                    dealTemplateOneOrder(tid, orderIdLong, verOrderSmsCarList);                    this.sendShopSms(verOrderSmsCarList);                }            } else {                // 满足条件的订单  即原订单流程没有走完，发送模板3                List<VerOrderSmsCar> verOrderSmsCarList = verOrderSmsCarDao.getSmsCarOrderByOrderId(orderId);                //返回数据字段id                if (CollectionUtils.isNotEmpty(verOrderSmsCarList)) {                    return;                }                dealTemplateThreeOrder(tid, orderId);            }        }        // 发送状态变更消息        if(isCar){            this.sendVerStore(orderId, isShop ? 1 : 0);        }    } catch (Exception e) {        LOGGER.error("监听MQ消息处理异常 : {}", e);        Profiler.functionError(callerInfo);    } finally {        Profiler.registerInfoEnd(callerInfo);    }}

public boolean execute(Context context) throws Exception {    if (context == null) {        throw new IllegalArgumentException();    } else {        this.frozen = true;        boolean saveResult = false;        Exception saveException = null;        int i = false;        int n = this.commands.length;        int i;        for(i = 0; i < n; ++i) {            try {                saveResult = this.commands[i].execute(context);                if (saveResult) {                    break;                }            } catch (Exception var11) {                saveException = var11;                break;            }        }        if (i >= n) {            --i;        }        boolean handled = false;        boolean result = false;        for(int j = i; j >= 0; --j) {            if (this.commands[j] instanceof Filter) {                try {                    result = ((Filter)this.commands[j]).postprocess(context, saveException);                    if (result) {                        handled = true;                    }                } catch (Exception var10) {                }            }        }        if (saveException != null && !handled) {            throw saveException;        } else {            return saveResult;        }    }}

/** * 订单拆分消息（拆单消息） * @author xxx * @date xxxx-xx-xx xx:xx */@Service("odcDivideOrderHandler")public class OdcDivideOrderHandler extends BaseOrderHandler implements MqMessageHandler<List<VerOrder>> {    /**     * 消息分派处理     */    @Resource(name="odcDivideOrderChain")    private Chain odcDivideOrderChain;    /**     * 基于MVEL表达式过滤执行器的筛选规则     */    private final Map<String, String> expressionMap = new HashMap<String, String>() {        {            //派单过滤规则            put("tech_dispatch_rule", "return sendPayMap.get(\"XXX\") == X && sendPayMap.get(\"XXX\") == X;");        }    };    /**     * @param tid        处理事件     * @param messageDTO MQ消息     * @return 处理结果     * @throws Exception 处理异常     */    private boolean handleMessage(long tid, MqMessageDTO<List<VerOrder>> messageDTO) throws Exception {         List<VerOrder> verOrderList = messageDTO.getObject();        try {            //上下文内容            Context context = new ContextBase();            //1.处理时间            context.put(Constants.TID, tid);            //2.派单列表            context.put(Constants.VER_ORDER_LIST,carOrderList);            //3.操作过滤规则            context.put(Constants.EXPRESSION_RULE_MAP,expressionMap);            odcDivideOrderChain.execute(context);        } catch (Exception ex) {            //此次代码省略........        }        return true;    }}

/** * 派单Handler * * @author xxx  * @date xxxx-xx-xx xx:xx */@Service("addedTechDispatchHandler")public class AddedTechDispatchHandler implements Command {    /**     * 派单消息topic     */    @Value("${xxx}")    private String topic;    /**     * 消息生产     */    @Resource(name = "xxxxx")    private MessageProducer messageProducer;    @Override    public boolean execute(Context context) throws Exception {        Object tid = context.get(Constants.TID);        Object object = context.get(Constants.VER_ORDER_LIST);        if (!(object instanceof List)) {            return false;        }        //订单列表        List<VerOrder> orders = (List<VerOrder>) object;        //列表为空        if (CollectionUtils.isEmpty(orders)) {            return false;        }        //过滤规则        Object ruleObj = context.get(Constants.EXPRESSION_RULE_MAP);        if (!(ruleObj instanceof Map)) {            return false;        }        //派单规则        Object obj = ((Map) ruleObj).get(Constants.TECH_DISPATCH_RULE);        //没有配置规则直接返回        if (!(obj instanceof String)) {            return false;        }        String expression = (String) obj;        if (StringUtils.isBlank(expression)) {            return false;        }        for (VerOrder verOrder : orders) {            //发送派单消息            this.sendTechDispatch(tid, verOrder, expression);        }        return false;    }
    /**     * 发送技师派单消息     *     * @param tid      处理时间     * @param verOrder 订单     */    public void sendTechDispatch(Object tid, VerOrder verOrder, String expression) {        try {            //派单规则判断，false-不派单，true-需要派单            if (!SendPayUtil.isExpression(expression, verOrder.getSendPayMap())) {                return;            }            String cxt = JSON.toJSONString(verOrder);            Message message = new Message(topic, cxt, verOrder.getOrderId().toString());            messageProducer.send(message);        } catch (JMQException e) {           //此次代码省略........        } catch (Exception e) {           //此次代码省略........        } finally {           //此次代码省略........        }    }}

/** *  sendPayMap表达式解析 * @param expression 表达式 * @param sendPayMap 订单SendPayMap值 * @return 解析结果 */public static boolean isExpression(String expression,String sendPayMap){    //sendPayMap为空    if (StringUtils.isBlank(sendPayMap)) {        return false;    }    Map map = null;    try {        map = JSON.parseObject(sendPayMap, Map.class);    } catch (Exception ex) {        LOGGER.error("sendPayMap格式转化错误", ex);    }    //map    if (map == null || map.isEmpty()) {        return false;    }    Map<String,Map> param = new HashMap<>(1);    param.put(Constant.SEND_PAY_MAP,map);    return (Boolean)MVEL.eval(expression,param);}

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"       xsi:schemaLocation="       http://www.springframework.org/schema/beans       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"       default-lazy-init="false" default-autowire="byName">    <bean id="odcOutStockFullOrderChain" class="org.apache.commons.chain.impl.ChainBase">        <constructor-arg>            <array>                <ref bean="addedOrderWangShiFuHandler"/>                <ref bean="addedTechDispatchHandler"/>            </array>        </constructor-arg>    </bean>    <bean id="odcDivideOrderChain" class="org.apache.commons.chain.impl.ChainBase">        <constructor-arg>            <array>                <ref bean="addedTechDispatchHandler"/>            </array>        </constructor-arg>    </bean>    <bean id="odcUndividedOrderChain" class="org.apache.commons.chain.impl.ChainBase">        <constructor-arg>            <array>                <ref bean="addedTechDispatchHandler"/>            </array>        </constructor-arg>    </bean></beans>