数据库可以定义表不同列之间的计算公式，进行自动公式计算，但如何实现行上的动态公式计算呢？行由于可以动态扩展，在某些应用场景下将能很好的解决实际问题。
1、VS2012新建一个WPF应用程序WpfApp_DynCalc，并添加一个类DynCalc.cs，如下图：
2、编辑MainWindow.xaml，代码如下：
1 <Window x:Class="WpfApp_DynCalc.MainWindow"
2 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4 Title="WPF动态计算示例" Height="350" Width="525">
5 <Grid>
6 <Grid.Resources>
7 <Style TargetType="DataGrid">
8 <!--网格线颜色-->
9 <Setter Property="CanUserResizeColumns" Value="false"/>
10 <Setter Property="Background" Value="#E6DBBB" />
11 <Setter Property="BorderBrush" Value="#d6c79b" />
12 <Setter Property="HorizontalGridLinesBrush">
13 <Setter.Value>
14 <SolidColorBrush Color="#d6c79b"/>
15 </Setter.Value>
16 </Setter>
17 <Setter Property="VerticalGridLinesBrush">
18 <Setter.Value>
19 <SolidColorBrush Color="#d6c79b"/>
20 </Setter.Value>
21 </Setter>
22 </Style>
23
24 <!--标题栏样式-->
25 <!--<Style TargetType="DataGridColumnHeader" > 26 <Setter Property="Width" Value="50"/> 27 <Setter Property="Height" Value="30"/> 28 <Setter Property="FontSize" Value="14" /> 29 <Setter Property="Background" Value="White" /> 30 <Setter Property="FontWeight" Value="Bold"/> 31 </Style>-->
32
33 <Style TargetType="DataGridColumnHeader">
34 <Setter Property="SnapsToDevicePixels" Value="True" />
35 <Setter Property="MinWidth" Value="0" />
36 <Setter Property="MinHeight" Value="28" />
37 <Setter Property="Foreground" Value="#323433" />
38 <Setter Property="FontSize" Value="14" />
39 <Setter Property="Cursor" Value="Hand" />
40 <Setter Property="Template">
41 <Setter.Value>
42 <ControlTemplate TargetType="DataGridColumnHeader">
43 <Border x:Name="BackgroundBorder" BorderThickness="0,1,0,1"
44 BorderBrush="#e6dbba"
45 Width="Auto">
46 <Grid >
47 <Grid.ColumnDefinitions>
48 <ColumnDefinition Width="*" />
49 </Grid.ColumnDefinitions>
50 <ContentPresenter Margin="0,0,0,0" VerticalAlignment="Center" HorizontalAlignment="Center"/>
51 <Path x:Name="SortArrow" Visibility="Collapsed" Data="M0,0 L1,0 0.5,1 z" Stretch="Fill" Grid.Column="2" Width="8" Height="6" Fill="White" Margin="0,0,50,0"
52 VerticalAlignment="Center" RenderTransformOrigin="1,1" />
53 <Rectangle Width="1" Fill="#d6c79b" HorizontalAlignment="Right" Grid.ColumnSpan="1" />
54 <!--<TextBlock Background="Red"> 55 <ContentPresenter></ContentPresenter></TextBlock>-->
56 </Grid>
57 </Border>
58 </ControlTemplate>
59 </Setter.Value>
60 </Setter>
61 <Setter Property="Height" Value="25"/>
62 </Style>
63 <!--行样式触发-->
64 <!--背景色改变必须先设置cellStyle 因为cellStyle会覆盖rowStyle样式-->
65 <Style TargetType="DataGridRow">
66 <Setter Property="Background" Value="#F2F2F2" />
67 <Setter Property="Height" Value="25"/>
68 <Setter Property="Foreground" Value="Black" />
69 <Style.Triggers>
70 <!--隔行换色-->
71 <Trigger Property="AlternationIndex" Value="0" >
72 <Setter Property="Background" Value="#e7e7e7" />
73 </Trigger>
74 <Trigger Property="AlternationIndex" Value="1" >
75 <Setter Property="Background" Value="#f2f2f2" />
76 </Trigger>
77
78 <Trigger Property="IsMouseOver" Value="True">
79 <Setter Property="Background" Value="LightGray"/>
80 <!--<Setter Property="Foreground" Value="White"/>-->
81 </Trigger>
82
83 <Trigger Property="IsSelected" Value="True">
84 <Setter Property="Foreground" Value="Black"/>
85 </Trigger>
86 </Style.Triggers>
87 </Style>
88
89 <!--单元格样式触发-->
90 <Style TargetType="DataGridCell">
91 <Setter Property="Template">
92 <Setter.Value>
93 <ControlTemplate TargetType="DataGridCell">
94 <TextBlock TextAlignment="Center" VerticalAlignment="Center" >
95 <ContentPresenter />
96 </TextBlock>
97 </ControlTemplate>
98 </Setter.Value>
99 </Setter>
100 <Style.Triggers>
101 <Trigger Property="IsSelected" Value="True">
102 <!--<Setter Property="Background" Value="White"/> 103 <Setter Property="BorderThickness" Value="0"/>-->
104 <Setter Property="Foreground" Value="Black"/>
105 </Trigger>
106 </Style.Triggers>
107 </Style>
108 </Grid.Resources>
109
110
111 <DataGrid Name="dgrid" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Height="256" Width="498" AutoGenerateColumns="False" >
112 <DataGrid.Columns>
113 <DataGridTextColumn Header="指标" Binding="{Binding Zb}" Width="118"/>
114 <DataGridTextColumn Header="值" Binding="{Binding Value}" Width="100"/>
115 <DataGridTextColumn Header="公式" Binding="{Binding Formula}" Width="188"/>
116 </DataGrid.Columns>
117 </DataGrid>
118 <Button Content="计 算" HorizontalAlignment="Left" Margin="419,281,0,0" VerticalAlignment="Top" Width="85" Click="Button_Click_1" Height="28" />
119 <TextBlock Name="lblResult" HorizontalAlignment="Left" Margin="28,281,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top"/>
120
121 </Grid>
122 </Window>
3、编辑后台文件MainWindow.xaml.cs，代码如下：
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Threading.Tasks; 6 using System.Windows; 7 using System.Windows.Controls; 8 using System.Windows.Data; 9 using System.Windows.Documents; 10 using System.Windows.Input; 11 using System.Windows.Media; 12 using System.Windows.Media.Imaging; 13 using System.Windows.Navigation; 14 using System.Windows.Shapes; 15
16 using System.Collections.ObjectModel; 17 namespace WpfApp_DynCalc 18 { 19 /// <summary>
20 /// MainWindow.xaml 的交互逻辑 21 /// </summary>
22 public partial class MainWindow : Window 23 { 24 public MainWindow() 25 { 26 InitializeComponent(); 27
28
29 ObservableCollection<Dynformula> ofs = new ObservableCollection<Dynformula>(); 30 ofs.Add(new Dynformula { Zb = "A", Value = "1", Formula = "" }); 31 ofs.Add(new Dynformula { Zb = "B", Value = "2", Formula = "2*A+1" }); 32 ofs.Add(new Dynformula { Zb = "C", Value = "3", Formula = "B*B" }); 33 ofs.Add(new Dynformula { Zb = "D", Value = "4", Formula = "C-2" }); 34 ofs.Add(new Dynformula { Zb = "Z", Value = "5", Formula = "D+C" }); 35 this.dgrid.ItemsSource = ofs; 36
37
38 } 39
40 private void Button_Click_1(object sender, RoutedEventArgs e) 41 { 42 this.lblResult.Text = "计算..."; 43 this.dgrid.ItemsSource= DynCalc.CalcScript(ref this.dgrid); 44 this.lblResult.Text = "计算完成!"; 45
46 } 47 } 48
49 public class Dynformula 50 { 51 private string zb; 52
53 public string Zb 54 { 55 get { return zb; } 56 set { zb = value; } 57 } 58 private string value; 59
60 public string Value 61 { 62 get { return this.value; } 63 set { this.value = value; } 64 } 65 private string formula; 66
67 public string Formula 68 { 69 get { return formula; } 70 set { formula = value; } 71 } 72
73 } 74 }
3、编辑类DynCalc.cs，代码如下：
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Threading.Tasks; 6
7 namespace WpfApp_DynCalc 8 { 9 using System.Collections.ObjectModel; 10 using System.Windows; 11 using System.Windows.Controls; 12 using System.Reflection; 13 using System.Globalization; 14 using Microsoft.CSharp; 15 using System.CodeDom; 16 using System.CodeDom.Compiler; 17 public static class DynCalc 18 { 19
20 public static ObservableCollection<Dynformula> CalcScript(ref DataGrid dgrid) 21 { 22
23 CSharpCodeProvider objCSharpCodePrivoder = new CSharpCodeProvider(); 24 ICodeCompiler objICodeCompiler = objCSharpCodePrivoder.CreateCompiler(); 25 CompilerParameters objCompilerParameters = new CompilerParameters(); 26 objCompilerParameters.ReferencedAssemblies.Add("System.dll"); 27 objCompilerParameters.GenerateExecutable = false; 28 objCompilerParameters.GenerateInMemory = true; 29 CompilerResults cr = objICodeCompiler.CompileAssemblyFromSource(objCompilerParameters, GenerateCode(ref dgrid)); 30 if (cr.Errors.HasErrors) 31 { 32 Console.WriteLine("编译错误："); 33 foreach (CompilerError err in cr.Errors) 34 { 35 Console.WriteLine(err.ErrorText); 36 } 37 return null; 38 } 39 else
40 { 41 // 通过反射，调用实例
42 Assembly objAssembly = cr.CompiledAssembly; 43 object objDynCalc = objAssembly.CreateInstance("DynamicCodeGenerate.RunScript"); 44 //MethodInfo objMI = objHelloWorld.GetType().GetMethod("OutPut"); 45 //Console.WriteLine(objMI.Invoke(objHelloWorld, null));
46
47 ObservableCollection<Dynformula> ofsnew = new ObservableCollection<Dynformula>(); 48 //循环datagrid进行公式计算并赋值
49 for (int i = 0; i < dgrid.Items.Count; i++) 50 { 51 Dynformula item = dgrid.Items[i] as Dynformula; 52 if (item == null) 53 { 54 break; 55 } 56 string zb = item.Zb; 57 PropertyInfo pinfo = objDynCalc.GetType().GetProperty(zb); 58 if (pinfo != null && pinfo.CanRead) { 59 //获取属性get值
60 object obj_Name = pinfo.GetValue(objDynCalc, null); 61 // item.Value = obj_Name.ToString();
62 ofsnew.Add(new Dynformula { Zb = item.Zb, Value = obj_Name.ToString(), Formula = item.Formula}); 63 } 64 } 65 return ofsnew; 66 } 67 } 68 /// <summary>
69 /// 计算逻辑C#脚本动态构建 70 /// </summary>
71 /// <param name="dgrid">存有指标以及指标计算公式的datagrid</param>
72 /// <returns>C#脚本</returns>
73 static string GenerateCode(ref DataGrid dgrid) 74 { 75 StringBuilder sb = new StringBuilder(); 76 StringBuilder sb构建函数内容 = new StringBuilder(); 77 sb.Append("using System;"); 78 sb.Append(Environment.NewLine); 79 sb.Append("namespace DynamicCodeGenerate"); 80 sb.Append(Environment.NewLine); 81 sb.Append("{"); 82 sb.Append(Environment.NewLine); 83 sb.Append(" public class RunScript"); 84 sb.Append(Environment.NewLine); 85 sb.Append(" {"); 86 //------------------------------------------------------------
87 for(int i=0;i<dgrid.Items.Count;i++) 88 { 89 Dynformula item = dgrid.Items[i] as Dynformula; 90 if (item == null) 91 { 92 break; 93 } 94 string zb = item.Zb; 95 sb.Append(Environment.NewLine); 96 sb.AppendFormat(" public double _{0};", item.Zb); 97 sb.Append(Environment.NewLine); 98 sb.AppendFormat(" public double {0}",item.Zb); 99 sb.Append(Environment.NewLine); 100 sb.Append(" {"); 101 sb.Append(Environment.NewLine); 102
103 if (item.Formula.Trim() != "") 104 { 105 sb.Append(" set{ "+item.Zb+"=value;}" ); 106 sb.Append(Environment.NewLine); 107 sb.Append(" get{return "+ item.Formula + ";}"); 108 } 109 else
110 { 111 sb.Append(" set{ _" + item.Zb + "=value;}"); 112 sb.Append(Environment.NewLine); 113 sb.Append(" get{return _"+item.Zb+";} "); 114 sb.Append(Environment.NewLine); 115 sb构建函数内容.Append(" _" + item.Zb + "=" + item.Value); 116 } 117 sb.Append(Environment.NewLine); 118 sb.Append(" }"); 119 sb.Append(Environment.NewLine); 120 } 121 //-------------------------------------------- 122 //构造函数进行赋值
123 sb.Append(Environment.NewLine); 124 sb.Append(" public RunScript()"); 125 sb.Append(Environment.NewLine); 126 sb.Append(" {"); 127 sb.Append(Environment.NewLine); 128 sb.AppendFormat(" {0};",sb构建函数内容.ToString()); 129 sb.Append(Environment.NewLine); 130 sb.Append(" }"); 131 sb.Append(Environment.NewLine); 132
133 //----------------------------------------------
134 sb.Append(Environment.NewLine); 135 sb.Append(" public string OutPut()"); 136 sb.Append(Environment.NewLine); 137 sb.Append(" {"); 138 sb.Append(Environment.NewLine); 139 sb.Append(" return \"Hello world!\";"); 140 sb.Append(Environment.NewLine); 141 sb.Append(" }"); 142 //-----------------------------------------
143 sb.Append(Environment.NewLine); 144 sb.Append(" }"); 145 sb.Append(Environment.NewLine); 146 sb.Append("}"); 147
148 string code = sb.ToString(); 149 Console.WriteLine(code); 150 return code; 151 } 152
153 } 154 }
4、运行程序，其中值列的值为初始值，点击计算后会根据公式列配置进行动态计算，初始化界面如下:
5、点击计算后界面如下：
可见现在的值是根据公式配置进行动态计算的。当然代码经过扩展还可以支持函数和简单的逻辑判断，如if ...else等。实现更强大的逻辑处理。