C#工作流中如何實現條件分支

在C#工作流中實現條件分支可以使用條件分支活動（IfElseActivity）或Switch活動（SwitchActivity）來實現。以下是一個簡單的示例代碼：

using System;
using System.Workflow.Activities;

namespace ConditionalWorkflow
{
    class Program
    {
        static void Main(string[] args)
        {
            WorkflowRuntime workflowRuntime = new WorkflowRuntime();

            IfElseActivity ifElseActivity = new IfElseActivity();
            CodeActivity conditionActivity = new CodeActivity();
            conditionActivity.ExecuteCode += new EventHandler(conditionActivity_ExecuteCode);
            ifElseActivity.Activities.Add(conditionActivity);

            CodeActivity trueActivity = new CodeActivity();
            trueActivity.ExecuteCode += new EventHandler(trueActivity_ExecuteCode);
            ifElseActivity.ThenActivities.Add(trueActivity);

            CodeActivity falseActivity = new CodeActivity();
            falseActivity.ExecuteCode += new EventHandler(falseActivity_ExecuteCode);
            ifElseActivity.ElseActivities.Add(falseActivity);

            SequentialWorkflowActivity workflow = new SequentialWorkflowActivity();
            workflow.Activities.Add(ifElseActivity);

            workflowRuntime.WorkflowCompleted += new EventHandler<WorkflowCompletedEventArgs>(workflowRuntime_WorkflowCompleted);
            workflowRuntime.WorkflowTerminated += new EventHandler<WorkflowTerminatedEventArgs>(workflowRuntime_WorkflowTerminated);

            workflowRuntime.CreateWorkflow(workflow).Start();

            Console.ReadLine();
        }

        static void conditionActivity_ExecuteCode(object sender, EventArgs e)
        {
            Console.WriteLine("Checking condition...");
            // Simulate a condition
            Random random = new Random();
            bool condition = random.Next(0, 2) == 1;

            ((CodeActivity)sender).WorkflowExecutionContext.ConditionResult = condition;
        }

        static void trueActivity_ExecuteCode(object sender, EventArgs e)
        {
            Console.WriteLine("Condition is true");
        }

        static void falseActivity_ExecuteCode(object sender, EventArgs e)
        {
            Console.WriteLine("Condition is false");
        }

        static void workflowRuntime_WorkflowCompleted(object sender, WorkflowCompletedEventArgs e)
        {
            Console.WriteLine("Workflow completed");
        }

        static void workflowRuntime_WorkflowTerminated(object sender, WorkflowTerminatedEventArgs e)
        {
            Console.WriteLine("Workflow terminated");
        }
    }
}

在上面的示例中，我們創建了一個簡單的工作流，其中包含一個條件分支活動（IfElseActivity），根據一個隨機生成的條件執行不同的代碼。條件的結果通過CodeActivity中的ConditionResult屬性設置，然后根據條件的結果執行對應的代碼。當工作流執行完成時，會觸發WorkflowCompleted事件；如果工作流終止，則會觸發WorkflowTerminated事件。