基于RulesEngine的业务规则实现

　　规则引擎由推理引擎发展而来，是一种嵌入在应用程序中的组件，实现了将业务决策从应用程序代码中分离出来，并使用预定义的语义模块编写业务决策。接受数据输入，解释业务规则，并根据业务规则做出业务决策。比较常见的业务规则引擎有Drools、VisualRules 和iLog。这里介绍另外一个C#开源工具RulesEngine。下面通过一个例子来他如何使用。

1 项目结构

在RulesEngine源代码中添加一个RulesEngineDemo的窗体应用程序，然后引用需要的类库，如下图所示：

2 订单等实体类定义

这里用订单的场景来用规则引擎处理折扣的业务逻辑：

    public class Order
    {
        public double amount;
        public double num;
        public double discount;
        public double afteramount;
        public DateTime datetime;
        public List<items> ItemLists;
        public string maker;//购买人
        public string wfprocess;//审批人
        public string wfprocessname;//审批人
        public string memo;//备注

        public override string ToString()
        {
            string res = string.Format("折扣={0},金额={1},审批人={2}({4}),折后金额={3}", discount, amount, wfprocess, afteramount,wfprocessname);
            return res;
        }
    }
    //用户
    public class Emp
    {
        public string id;
        public string leader;
        public string name;
    }
    //明细
    public class items
    {
        public string productid;
        public string productname;
        public double price;
        public double num;
        public double discount;
        public double amount;
        public double afteramount;

    }

 3 窗体定义

下面我们创建一个订单明细的窗体，用来修改金额等数据，用来测试业务规则是否正常运行：、

    public partial class FrmOrder : Form
    {
        public FrmOrder()
        {
            InitializeComponent();
            dgvOrder = this.dataGridView1;
        }

        public DataGridView dgvOrder;
        private void FrmOrder_Load(object sender, EventArgs e)
        {
            this.dataGridView1.Rows.Add(new object[] { "1", "p1", "20", "10", "200", "1","200","01.01" });
            this.dataGridView1.Rows.Add(new object[] { "2", "p2", "1", "8", "8", "1", "8", "01.01" });

        }

        private void 保存SToolStripButton_Click(object sender, EventArgs e)
        {
            this.Hide();
        }
    }

然后我们定义一个主界面来定义规则和调用处理逻辑：

    using RulesEngine;
    using RulesEngine.BooEvaluator;
    public partial class Form1 : Form
    {

        DataGridView dgvOrder = null;
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.dataGridView1.Rows.Add(new object[] {"return (订单.金额>200)",@"
               订单.折扣=0.9;
               订单.审批人=""admin"";
               订单.折后金额=订单.金额*订单.折扣;
               订单.备注 = ""规则引擎产生"";
               return true;" });
            this.dataGridView1.Rows.Add(new object[] {"return (订单.金额<=200 且 订单.金额>100)",@"
               订单.折扣=0.8;
               订单.折后金额=订单.金额*订单.折扣;
               订单.备注 = ""规则引擎产生"";
               return true;" });

            this.dataGridView1.Rows.Add(new object[] {"return (订单.金额<=100 且 订单.金额>0)",@"
               订单.折扣=1.0;
               订单.折后金额=订单.金额*订单.折扣;
               订单.备注 = ""规则引擎产生"";
               return true;" });

        }
        //run
        private void 保存SToolStripButton_Click(object sender, EventArgs e)
        {
           
           
              DslRuleTests test = new DslRuleTests();
              test.Setup();

              //test.EvaluateRules();

              var order = test.EvaluateRules(this.dataGridView1, dgvOrder);
              this.txtResults.Text = order.ToString();

          
           
        }

        private void toolStripButton1_Click(object sender, EventArgs e)
        {
            FrmOrder frm = new FrmOrder();

            frm.ShowDialog();

            dgvOrder = frm.dgvOrder;
        }
    }
  
    public class DslRuleTests
    {
        private BooLangEvaluator evaluator;

        private List<Emp> listEmp = new List<Emp>();
        
        public void Setup()
        {
            var dslEngineStorage = new DslEngineStorage();
          
            evaluator = new BooLangEvaluator(dslEngineStorage);
        
            listEmp.Add(new Emp { id = "01", leader ="00" ,name="jack"});
            listEmp.Add(new Emp { id = "01.01", leader = "01", name = "smith" });
            listEmp.Add(new Emp { id = "01.01.01", leader = "01.01", name = "john" });

         
        }
        //审批处理
        private void SP(Order o)
        {
           
            foreach (Emp emp in listEmp)
            {
                if (emp.id == o.maker)
                {
                    o.wfprocess = emp.leader;
                    o.wfprocessname = getName(o.wfprocess);
                }
            }

           
        }
        //获取职工姓名
        private string getName(string id)
        {
            foreach (Emp emp in listEmp)
            {
                if (emp.id == id)
                {

                    return emp.name;
                }
            }
            return "";
        }
        //求和
        private void SumAmount(Order o)
        {
            var sum = o.ItemLists.AsQueryable().Sum(x => x.amount);
            o.amount = sum;
        }
        //解析规则脚本
        public Order EvaluateRules(DataGridView dgv,DataGridView dgvOrder)
        {
             Order order =new Order { memo = "", maker = "01.01", discount = 1, datetime = DateTime.Now };
             order.ItemLists = new List<items>();
            foreach (DataGridViewRow dr in dgvOrder.Rows)
            {
                if (dr.Cells[0].Value != null)
                {
                    var item = new items
                    {
                        productid = dr.Cells[0].Value.ToString(),
                        productname = dr.Cells[1].Value.ToString(),
                        price = double.Parse(dr.Cells[2].Value.ToString()),
                        num = double.Parse(dr.Cells[3].Value.ToString()),
                        amount = double.Parse(dr.Cells[4].Value.ToString()),
                        discount = double.Parse(dr.Cells[5].Value.ToString()),
                        afteramount = double.Parse(dr.Cells[6].Value.ToString())

                    };

                    order.ItemLists.Add(item);
                }
            }

            SumAmount(order);
            SP(order);
            string strDslStatement="";
            string strDslActivity = "";
            EvaluatorAccessPoint.DslConditionEvaluator = evaluator;

            foreach (DataGridViewRow dr in dgv.Rows)
            {

                strDslStatement = dr.Cells[0].Value.ToString()
                .Replace("订单", "this")
                .Replace("金额", "amount")
                .Replace("且", "and")
                .Replace("或", "or");
                strDslActivity = dr.Cells[1].Value.ToString()
                     .Replace("折扣", "discount")
                     .Replace("折后金额", "afteramount")
                     .Replace("金额", "amount")
                     .Replace("订单", "this")
                     .Replace("备注", "memo")
                     .Replace("审批人", "wfprocessname")
                     .Replace("且", "and")
                     .Replace("或", "or");

                var conditionRule = new DslCondition { DslStatement = strDslStatement };

                var rule = new ActivityRule(conditionRule, new DslActivity
                {
                    DslStatement = strDslActivity
                });

                var result = rule.Evaluate(order);
                if (result)
                {
                    //break;
                    return order;
                    
                }
               

            }
            return null;
           
        }

    }

 4 结果展示

运行代码，界面如下：