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[] { "", "p1", "", "", "", "","","01.01" });
             this.dataGridView1.Rows.Add(new object[] { "", "p2", "", "", "", "", "", "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 = "", leader ="" ,name="jack"});
             listEmp.Add(new Emp { id = "01.01", leader = "", 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 = , datetime = DateTime.Now };
              order.ItemLists = new List<items>();
             foreach (DataGridViewRow dr in dgvOrder.Rows)
             {
                 if (dr.Cells[].Value != null)
                 {
                     var item = new items
                     {
                         productid = dr.Cells[].Value.ToString(),
                         productname = dr.Cells[].Value.ToString(),
                         price = double.Parse(dr.Cells[].Value.ToString()),
                         num = double.Parse(dr.Cells[].Value.ToString()),
                         amount = double.Parse(dr.Cells[].Value.ToString()),
                         discount = double.Parse(dr.Cells[].Value.ToString()),
                         afteramount = double.Parse(dr.Cells[].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[].Value.ToString()
                 .Replace("订单", "this")
                 .Replace("金额", "amount")
                 .Replace("且", "and")
                 .Replace("或", "or");
                 strDslActivity = dr.Cells[].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：