C#工作流中如何实现条件分支

在C#工作流中实现条件分支可以使用条件分支活动（IfElseActivity）或Switch活动（SwitchActivity）来实现。以下是一个简单的示例代码：

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，我们创建了一个简单的工作流，其中包含一个条件分支活动（IfElseActivity），根据一个随机生成的条件执行不同的代码。条件的结果通过CodeActivity中的ConditionResult属性设置，然后根据条件的结果执行对应的代码。当工作流执行完成时，会触发WorkflowCompleted事件；如果工作流终止，则会触发WorkflowTerminated事件。