工作流学习过程-开篇

最近由于项目原因，比较闲，闲暇时间学习了下工作流方面的知识。版本为3.5
学习资料为wf高级程序设计
感觉书里内容比较基础、层次很清晰、代码全，非常适合工作流入门学习
先来看看什么是工作流？
流就是处理一件事情的步骤喽，那工作流就是要完成某项工作的步骤集合了（个人理解）
由于本人水平很哇。故不能提供代码的解释部分，紧提供实例及代码

例1.计算器
运行时效果如图所示

根据实际需要若完成该计算器的功能
1-0 10个数字的Click事件应该相应同一个事件btnNum_Click
+-*/四个运算符号Click事件应该响应同一个事件btnOperator_Click
= 和 C 各为一个事件btnEqual_Click和btnClear_Click
实现代码如下。写的比较烂

        private int num1, num2;
        private string opera;
        private double result = 0;

        private void btnEqual_Click(object sender, EventArgs e)
        {
            num2 = int.Parse(txt.Text);
            switch (opera)
            {
                case "+":
                    result = num1 + num2;
                    break;
                case "-":
                    result = num1 - num2;
                    break;
                case "*":
                    result = num1 * num2;
                    break;
                case "/":
                    if (num2 == 0)
                        throw new ArgumentException("被除数为0");
                    result = num1 / num2;
                    break;
                default:
                    throw new ArgumentException("错误的操作符");
                    break;
            }
            txt.Text = result.ToString();
        }

        private void btnClear_Click(object sender, EventArgs e)
        {
            this.txt.Text = string.Empty;
        }

        private void btnNum_Click(object sender, EventArgs e)
        {
            Button btn = sender as Button;
            this.txt.AppendText(btn.Text);
        }

        private void btnOperator_Click(object sender, EventArgs e)
        {
            num1 = int.Parse(txt.Text);
            txt.Text = string.Empty;
            Button btn = sender as Button;
            opera = btn.Text;
        }

一个简单的计算器功能就基本完成了。。当然了这里有很多bug的。。要按最正确的方式使用（:-D）
那我们如何来使用工作流来完成此项工作呢
来看看工作流如图：

后台代码如下：

public sealed partial class CalculatorWorkflowActivity : SequentialWorkflowActivity
    {
        public CalculatorWorkflowActivity()
        {
            InitializeComponent();
        }

        public int Num1 { get; set; }
        public int Num2 { get; set; }
        public string Operator { get; set; }
        public double Result { get; set; }

        private void Add_ExecuteCode(object sender, EventArgs e)
        {
            Result = Num1 + Num2;
        }

        private void Sub_ExecuteCode(object sender, EventArgs e)
        {
            Result = Num1 - Num2;
        }

        private void Mul_ExecuteCode(object sender, EventArgs e)
        {
            Result = Num1 * Num2;
        }

        private void Div_ExecuteCode(object sender, EventArgs e)
        {
            if (Num2 == 0)
                throw new ArgumentException("除数为0");
            Result = (double)Num1 / (double)Num2;
        }

        private void Fault_ExecuteCode(object sender, EventArgs e)
        {
            throw new ArgumentException("无效的操作符");
        }
    }

那么我们的应用程序又如何来使用它呢
只需将btnEqual_Click 代码修改如下即可

 

private void btnEqual_Click(object sender, EventArgs e)
        {
            num2 = int.Parse(txt.Text);
            using (WorkflowRuntime workflowRuntime = new WorkflowRuntime())
            {
                AutoResetEvent waitHandle = new AutoResetEvent(false);
                workflowRuntime.WorkflowCompleted += delegate(object sender1, WorkflowCompletedEventArgs e1)
                {
                    waitHandle.Set();
                };
                workflowRuntime.WorkflowTerminated += delegate(object sender1, WorkflowTerminatedEventArgs e1)
                {
                    Console.WriteLine(e1.Exception.Message);
                    waitHandle.Set();
                };

                Dictionary<string, object> parameters = new Dictionary<string, object>();
                parameters.Add("Num1", num1);
                parameters.Add("Num2", num2);
                parameters.Add("Operator", opera);

                WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(CalculatorWorkflowActivity), parameters);
                instance.Start();
                waitHandle.WaitOne();
                txt.Text = result.ToString();
            }
        }

试运行。。结果呢？运行结果在哪里？

我们知道result现在应该是个空值，即使将值赋予txt控件也无济于事~

原来workflowRuntime的WorkflowCompleted事件提供的参数WorkflowCompletedEventArgs里的属性OutputParameters提供了提取操作结果的功能

只需在事件中将加入如下代码即可

result = (double)(e1.OutputParameters["Result"]);

 再运行即可得到和我们之前windowsForm一样的东西了