如何在调用WCF服务之前弹出一个确认对话框？

   1: public class InvocationConfirmationInteractiveChannelInitializer : IInteractiveChannelInitializer

   2: {

   3:     public const string ConfirmMessage = "程序执行过程涉及到WCF服务调用，是否继续？";

   4:     public IAsyncResult BeginDisplayInitializationUI(IClientChannel channel, AsyncCallback callback, object state)

   5:     {

   6:         bool cancel = MessageBox.Show(ConfirmMessage, "WCF服务调用确认", MessageBoxButtons.YesNo) == DialogResult.No;

   7:         return new SimpleAsynsResult(cancel);

   8:     }

   9:  

  10:     public void EndDisplayInitializationUI(IAsyncResult result)

  11:     {

  12:         SimpleAsynsResult asyncResult = (SimpleAsynsResult)result;

  13:         if((bool)asyncResult.AsyncState)

  14:         {

  15:             throw new InvocationCancelException("WCF服务调用被取消");

  16:         }

  17:     }

  18: }

  19:  

  20: public class SimpleAsynsResult:IAsyncResult

  21: {

  22:     public SimpleAsynsResult(object state)

  23:     {

  24:         this.AsyncState = state;

  25:     }

  26:  

  27:     public object AsyncState { get; private set; }

  28:     public WaitHandle AsyncWaitHandle { get; private set; }

  29:     public bool CompletedSynchronously

  30:     {

  31:         get { return true; }

  32:     }

  33:     public bool IsCompleted

  34:     {

  35:         get { return true; }

  36:     }

  37: }

   1: [AttributeUsage(AttributeTargets.Class | AttributeTargets.Interface)]

   2: public class InvocationConfirmationBehaviorAttribute : Attribute, IContractBehavior

   3: {

   4:     public void AddBindingParameters(ContractDescription contractDescription, ServiceEndpoint endpoint, BindingParameterCollection bindingParameters) { }

   5:     public void ApplyClientBehavior(ContractDescription contractDescription, ServiceEndpoint endpoint, ClientRuntime clientRuntime)

   6:     {

   7:         clientRuntime.InteractiveChannelInitializers.Add(new InvocationConfirmationInteractiveChannelInitializer());

   8:     }

   9:     public void ApplyDispatchBehavior(ContractDescription contractDescription, ServiceEndpoint endpoint, DispatchRuntime dispatchRuntime) { }

  10:     public void Validate(ContractDescription contractDescription, ServiceEndpoint endpoint) { }

  11: }

   1: [ServiceContract(Name = "CalculatorService", Namespace ="http://www.artech.com/")]

   2: 

   3: public interface ICalculator

   4: {

   5:     [OperationContract]

   6:     double Add(double x, double y);

   7: }

   1: public partial class Form1 : Form

   2: {

   3:     //其他成员

   4:     private void buttonCalculate_Click(object sender, EventArgs e)

   5:     {

   6:         this.textBoxResult.Text = string.Empty;

   7:         using (ChannelFactory<ICalculator> channelfactory = new ChannelFactory<ICalculator>("calculatorservice"))

   8:         {

   9:             ICalculator calculator = channelfactory.CreateChannel();

  10:             try

  11:             {

  12:                 double op1 = double.Parse(this.textBoxOp1.Text);

  13:                 double op2 = double.Parse(this.textBoxOp2.Text);

  14:                 double result = calculator.Add(op1,op2);

  15:                 this.textBoxResult.Text = result.ToString();

  16:             }

  17:             catch (InvocationCancelException)

  18:             {

  19:             }

  20:             catch (Exception ex)

  21:             {

  22:                 MessageBox.Show(ex.Message);

  23:             }

  24:         }

  25:     }

  26: }