规则引挚NxBRE文档纪要--流引挚简介(二)

上一篇都写总体上的认识,现在开始具体点,先把规则文件贴出来

<?xml version="1.0" encoding="UTF-8"?>
<xBusinessRules xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="xBusinessRules.xsd">
    <!-- global values -->
    <Integer id="10i" value="10"/>
    <Integer id="40i" value="40"/>  
    <ObjectLookup id="QuantityOrdered" objectId="CurrentOrder" member="Quantity"/>
    <Logic>
        <If>
            <And>
                <GreaterThanEqualTo leftId="ClientRating" rightId="ClientRatingThreshold">
                    <ObjectLookup id="ClientRating" objectId="CurrentOrder" member="ClientRating"/>
                    <String id="ClientRatingThreshold" value="C"/>
                </GreaterThanEqualTo>
            </And>
            <Do>
                <!-- Discount rules for high rate customers -->
                <Logic>
                    <If>
                        <And>
                            <GreaterThan leftId="QuantityOrdered" rightId="40i"/>
                        </And>
                        <Do>
                            <Evaluate id="AppliedDiscount">
                                <Parameter name="Percent" value=".7"/>
                            </Evaluate>
                        </Do>
                    </If>
                    <ElseIf>
                        <And>
                            <GreaterThan leftId="QuantityOrdered" rightId="10i"/>
                        </And>
                        <Do>
                            <Evaluate id="AppliedDiscount">
                                <Parameter name="Percent" value=".8"/>
                            </Evaluate>
                        </Do>
                    </ElseIf>
                    <Else>
                        <Evaluate id="AppliedDiscount">
                            <Parameter name="Percent" value=".9"/>
                        </Evaluate>
                    </Else>
                </Logic>
            </Do>
        </If>
        <Else>
            <!-- Discount rules for low rate customers -->
            <Logic>
                <If>
                    <And>
                        <GreaterThan leftId="QuantityOrdered" rightId="40i"/>
                    </And>
                    <Do>
                        <Evaluate id="AppliedDiscount">
                            <Parameter name="Percent" value=".9"/>
                        </Evaluate>
                    </Do>
                </If>
                <Else>
                    <Evaluate id="AppliedDiscount">
                        <Parameter name="Percent" value="1"/>
                    </Evaluate>
                </Else>
            </Logic>
        </Else>
    </Logic>
</xBusinessRules>

以下是关于上面的规则文件写的伪码
Percent就是返回的拆扣

int 10i = 10;
int 40i = 40;
Order order;
QuantityOrdered = CurrentOrder.QuantityOrdered;//数量
string ClientRatingThreshold = "C";//等级
double Percent;/**//*折扣*/
if(order.ClientRating/**//*客户等级*/ >= ClientRatingThreshold)// Discount rules for high rate customers 
{
    if(QuantityOrdered > 40i)
    {
        Percent = 0.7;
    }
    else if(QuantityOrdered > 10i)
    {
        Percent = 0.8;
    }
    else
    {
        Percent = 0.9;
    }
}
else// Discount rules for low rate customers 
{
    if(QuantityOrdered>40i)
    {
        Percent = 0.9;
    }
    else
    {
        Percent = 1;
    }
}

好了,费话不说,直接贴程序的主要代码吧

using System;
using System.Collections;
using System.Text;

using NxBRE.FlowEngine;
using NxBRE.FlowEngine.IO;

using BREFactory = NxBRE.FlowEngine.Factories.BREFactory;
using Reflection = NxBRE.Util.Reflection;

namespace MyDiscount
{   
    class Program
    {
        /**//// <summary>
        /// 规则xml文件名称
        /// </summary>
        public const string FLOW_RULES_FILENAME = "discount.xbre";
        public const string ORDER = "CurrentOrder";
        public const string APPLIED_DISCOUNT = "AppliedDiscount";
        public const string PERCENT = "Percent";

        /**//// <summary>
        /// 定单
        /// </summary>
        struct Order
        {
            public Int32 Quantity;
            public Double TotalCost;
            public string ClientRating;

            public Order(int _q, double _t, string _c){
                this.Quantity = _q;
                this.TotalCost = _t;
                this.ClientRating = _c;
            }
        }

        /**//// <summary>
        /// 计算结果
        /// </summary>
        /// <param name="aBRC">规则引挚上下文</param>
        /// <param name="aMap"></param>
        /// <param name="aStep"></param>
        /// <returns>结果</returns>
        static object AppliedDiscount(IBRERuleContext aBRC, IDictionary aMap, object aStep)
        {
            Order _order = (Order)aBRC.GetObject(ORDER);
            double _d = Convert.ToDouble(Reflection.CastValue(aMap[PERCENT], typeof(double)));
            return _order.TotalCost * _d;
        }

        static void Main(string[] args)
        {
            //载入规则
            IRulesDriver rulesDriver = new XBusinessRulesFileDriver(FLOW_RULES_FILENAME);
            //工厂
            BREFactory breFactory = new BREFactory();
            //引挚实例
            IFlowEngine bre = breFactory.NewBRE(rulesDriver);

            //委托实例
            ExecuteRuleDelegate executeRuleDelegate = new ExecuteRuleDelegate(AppliedDiscount);

            bre.RuleContext.SetFactory(APPLIED_DISCOUNT, new BRERuleFactory(executeRuleDelegate));

            //设置规则引挚环境变量
            Order order = new Order(5, 25, "A");
            bre.RuleContext.SetObject(ORDER, order);
            //执行
            bre.Process();
            //得到执行结果
            double result = (double)bre.RuleContext.GetResult(APPLIED_DISCOUNT).Result;

            Console.Out.WriteLine("\nOrder: Calculated discounted total={0} (expected: {1})\n",
                                      result,25);

            Console.ReadLine();
        }
    }
}

运行,输出
Order: Calculated discounted total=25 (expected: 25)
根据我们上面的规则走完得到了的拆扣的值

这个例子是我从原来的exapmles里面精简出来的,原先的例子把我真正要看的东西给搞得复杂化了了,所以写这个简单点,
这才是真正的HelloWorld!

具体我就不解释程序了,应该比较清晰了