P交互问题及案例分享(4)

接着，我们定义View的接口ICustomerView。ICustomerView定义了两个事件，CustomerSelected在用户从Gird中选择了某个条客户记录是触发，而CustomerSaving则在用户完成编辑点击OK按钮视图提交修改时触发。ICustomerView还定义了View必须完成的三个基本操作：绑定客户列表（ListAllCustomers）；显示单个客户信息到TextBox（DisplayCustomerInfo）；保存后清空可编辑控件（Clear）。

复制代码 代码如下:

 using System;
 namespace MVPDemo
 {
     public interface ICustomerView : IViewBase
     {
         event EventHandler<CustomerEventArgs> CustomerSelected;

         event EventHandler<CustomerEventArgs> CustomerSaving;

         void ListAllCustomers(Customer[] customers);

         void DisplayCustomerInfo(Customer customer);

         void Clear();
     }
 }

事件参数的类型CustomerEventArgs定义如下，两个属性CustomerId和Customer分别代表客户ＩＤ和具体的客户，它们分别用于上面提到的CustomerSelected和CustomerSaving事件。

复制代码 代码如下:

 using System;
 namespace MVPDemo
 {
     public class CustomerEventArgs : EventArgs
     {
         public string CustomerId
         { get; set; }

         public Customer Customer
         { get; set; }
     }
 }

而具体的Presenter定义在如下的CustomerPresenter类型中。在重写的OnViewSet方法中注册View的三个事件：Load事件中调用Model获取所有客户列表，并显示在View的Grid上；CustomerSelected事件中通过事件参数传递的客户ID调用Model获取相应的客户信息，显示在View的可编辑控件上；CustomerSaving则通过事件参数传递的被更新过的客户信息，调用Model提交更新。

复制代码 代码如下:

 using System.Windows.Forms;

 namespace MVPDemo
 {  
     public class CustomerPresenter: Presenter<ICustomerView>
     {
         public CustomerModel Model
         { get; private set; }

         public CustomerPresenter(ICustomerView view)
             : base(view)
         {
             this.Model = new CustomerModel();
         }

         protected override void OnViewSet()
         {
             this.View.Load += (sender, args) =>
                 {
                     Customer[] customers = this.Model.GetAllCustomers();
                     this.View.ListAllCustomers(customers);
                     this.View.Clear();
                 };
             this.View.CustomerSelected += (sender, args) =>
                 {
                     Customer customer = this.Model.GetCustomerById(args.CustomerId);
                     this.View.DisplayCustomerInfo(customer);
                 };
             this.View.CustomerSaving += (sender, args) =>
                 {
                     this.Model.UpdateCustomer(args.Customer);
                     Customer[] customers = this.Model.GetAllCustomers();
                     this.View.ListAllCustomers(customers);
                     this.View.Clear();
                     MessageBox.Show("The customer has been successfully updated!", "Successfully Update", MessageBoxButtons.OK, MessageBoxIcon.Information);
                 };
         }      
     }
 }