[WF4实践一] 使用 TryCatch 在 Flowchart 活动中进行错误处理

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原创最新推荐文章于 2025-06-29 04:45:00 发布 252 阅读 AI 写同款· GEO 优化 ›

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在此示例中，将促销代码和孩子数量作为变量传递到 Flowchart 活动，该活动将根据与促销代码相对应的公式计算折扣。此示例分为命令性代码版本和工作流设计器版本。

下表详细描述了 CreateFlowchartWithFaults 活动的变量。

参数	说明
promoCode	促销代码。类型：String 可能的值，括号中带有说明： Single（单身） MNK（已婚但没有孩子。） MWK（已婚并且有孩子。）
numKids	孩子数量。类型：int

参数

说明

promoCode

促销代码。类型：String

可能的值，括号中带有说明：

Single（单身）
MNK（已婚但没有孩子。）
MWK（已婚并且有孩子。）

numKids

孩子数量。类型：int

CreateFlowchartWithFaults 活动使用 FlowSwitch 活动，后者根据 promoCode 参数进行切换并使用以下公式计算折扣。

`promoCode` 的值	折扣 (%)
Single	10
MNK	15
MWK	15 + (1 – 1/`numberOfKids`)10 注意：此计算可能会引发 DivideByZeroException。因此，将折扣计算包装在 TryCatch* 活动中，该活动可捕获 DivideByZeroException 异常并将折扣设置为零。

 class Program
    {
        static void Main(string[] args)
        {
            // no fault expected
            Console.WriteLine("Invoke with Promo Code {0}, number of kids {1}", "Single", 0);
            IDictionary<string, object> inputs = new Dictionary<string, object>() { { "promoCode", "Single" }, { "numberOfKids", 0 } };
            WorkflowInvoker.Invoke(new PromotionalDiscountWorkflow(), inputs);

            // no fault expected
            Console.WriteLine("Invoke with Promo Code {0}, number of kids {1}", "MNK", 0);
            inputs = new Dictionary<string, object>() { { "promoCode", "MNK" }, { "numberOfKids", 0 } };
            WorkflowInvoker.Invoke(new PromotionalDiscountWorkflow(), inputs);

            // no fault expected
            Console.WriteLine("Invoke with Promo Code {0}, number of kids {1}", "MWK", 2);
            inputs = new Dictionary<string, object>() { { "promoCode", "MWK" }, { "numberOfKids", 2 } };
            WorkflowInvoker.Invoke(new PromotionalDiscountWorkflow(), inputs);

            //fault expected
            Console.WriteLine("Invoke with Promo Code {0}, number of kids {1}", "MWK", 0);
            inputs = new Dictionary<string, object>() { { "promoCode", "MWK" }, { "numberOfKids", 0 } };
            WorkflowInvoker.Invoke(new PromotionalDiscountWorkflow(), inputs);

            // wait for user input
            Console.WriteLine("\nPress enter to exit");
            Console.ReadLine();
        }
    }

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        <p:Flowchart.StartNode>
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              </WorkflowViewStateService.ViewState>
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                <p:Assign.To>
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            </scg:Dictionary>
          </WorkflowViewStateService.ViewState>
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              </scg:Dictionary>
            </WorkflowViewStateService.ViewState>
            <p:TryCatch VirtualizedContainerService.HintSize="200,53">
              <p:TryCatch.Try>
                <p:If Condition="[numberOfKids = 0]">
                  <p:If.Then>
                    <p:Throw Exception="[New System.DivideByZeroException ()]" />
                  </p:If.Then>
                  <p:If.Else>
                    <p:Assign>
                      <p:Assign.To>
                        <p:OutArgument x:TypeArguments="x:Double">[discount]</p:OutArgument>
                      </p:Assign.To>
                      <p:Assign.Value>
                        <p:InArgument x:TypeArguments="x:Double">[15 + (1 - 1 / numberOfKids) * 10]</p:InArgument>
                      </p:Assign.Value>
                    </p:Assign>
                  </p:If.Else>
                </p:If>
              </p:TryCatch.Try>
              <p:TryCatch.Catches>
                <p:Catch x:TypeArguments="s:DivideByZeroException">
                  <p:ActivityAction x:TypeArguments="s:DivideByZeroException">
                    <p:Sequence>
                      <p:WriteLine Text="["DivideByZeroException: Promo code is MWK - but number of kids = 0"]" />
                      <p:Assign>
                        <p:Assign.To>
                          <p:OutArgument x:TypeArguments="x:Double">[discount]</p:OutArgument>
                        </p:Assign.To>
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                </p:Catch>
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            </p:TryCatch>
            <p:FlowStep.Next>
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                <WorkflowViewStateService.ViewState>
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                    <av:Size x:Key="ShapeSize">213,63</av:Size>
                  </scg:Dictionary>
                </WorkflowViewStateService.ViewState>
                <p:WriteLine VirtualizedContainerService.HintSize="213,63" Text="["Discount calculated = " & discount]" />
              </p:FlowStep>
            </p:FlowStep.Next>
          </p:FlowStep>
          <p:FlowStep x:Key="MNK" x:Name="__ReferenceID3">
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                <p:InArgument x:TypeArguments="x:Double">[15.0R]</p:InArgument>
              </p:Assign.Value>
            </p:Assign>
            <p:FlowStep.Next>
              <x:Reference>__ReferenceID0</x:Reference>
            </p:FlowStep.Next>
          </p:FlowStep>
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              <x:Reference>__ReferenceID0</x:Reference>
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