asp.net MVC4 框架揭祕 讀書筆記系列2

 

1.2 MVC 變體

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MVC 是一種Pattern 另一種說法是ParaDigm 範例

模式和範例的區別在於前者能夠應用到具體的應用上，然後者則僅僅提供一些指導方針

1.2.1 MVP

Model View Presenter 交互圖

MVC 模式中元素之間 「混亂」的交互主要體如今容許View 和 Model 繞開Controller進行單獨交流，這在MVP 模式中獲得了充分解決

PV 模式 （passive View）

解決View很難測試的最好方法是讓他無需測試，讓UI處理更少邏輯，被動的交給Presenter來處理

暴漏UI不必定必須暴漏UI控件，

沒有必要寫成

public interface IemployeeSearchView1
{
    DropDownList Department { get; }
    GridView Employees { get; }
}

 而能夠經過數據的屬性來定義接口，這樣就能夠將presenter中的UI處理邏輯分離出來

public interface IemployeeSearchView
{
    IEnumerable<string> Departments { set; }
    string SelectedDedpartment { get; }
    IEnumerable<Employee> Employees { set; }
}

具體的實現方法以下：

public partial class _Default : System.Web.UI.Page, IemployeeSearchView
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    public IEnumerable<string> Departments
    {
        set
        {
            this.DropDownListDepartments.DataSource = value;
            this.DropDownListDepartments.DataBind();
        }
    }

    public string SelectedDedpartment
    {
        get { return this.DropDownListDepartments.SelectedValue; }
    }

    public IEnumerable<Employee> Employees
    {
        set
        {
            this.GridViewEmployees.DataSource = value;
            this.GridViewEmployees.DataBind();
        }
    }
}

這樣作意味着全部的UI邏輯均可以被測試，可是它要求將全部可供操做的UI元素定義在對應的接口中，無疑會增長Presenter 的複雜度，這就引出SC模式

SC模式（supervsing Controller）

View 和Presenter 之間的交互式整個MVP的核心，可否正確地應用MVP模式來架構應用，主要取決於View 和Presenter 之間的關係 在由model、View Presenter 組成的三角關係中，核心不是View 而是Presenter，Presenter 不只是View調用的中介，而是最終決定如何響應用戶交互行爲的決策者。

View 自己僅僅實現單純的獨立的UI處理邏輯，他處理的數據應該是Presneter實時推送過來的，因此View 儘量不去維護數據狀態，定義在IView的接口最好只包含方法，而避免屬性的定義，Presenter 所需的關於View的狀態應該在接收到View發送的用戶請求時一次性推送，而不須要經過View 的屬性去得到它

如下爲全部代碼

Model

public class Employee
    {
        public string Id { get; private set; }
        public string Name { get; private set; }
        public string Gender { get; private set; }
        public DateTime BirthDate { get; private set; }
        public string Department { get; private set; }

        public Employee(string id, string name, string gender, DateTime birthDate, string department)
        {
            this.Id = id;
            this.Name = name;
            this.Gender = gender;
            this.BirthDate = birthDate;
            this.Department = department;
        }
    }

EmployeeRespository

   public class EmployeeRepository
    {
        private static IList<Employee> employees;

        static EmployeeRepository()
        {
            employees = new List<Employee>();
            employees.Add(new Employee("001", "張三", "男", new DateTime(1981, 8, 1), "銷售部"));
            employees.Add(new Employee("001", "李四", "女", new DateTime(1982, 8, 4), "人事部"));
            employees.Add(new Employee("001", "王五", "男", new DateTime(1981, 9, 1), "人事部"));

        }

        public IEnumerable<Employee> GetEmployees(string department = "")
        {
            if (string.IsNullOrEmpty(department))
            {
                return employees;
            }
            return employees.Where(e => e.Department == department).ToArray();

        }
    }

IEmployeeSearchView

 public interface IEmployeeSearchView
    {
        void BindEmployees(IEnumerable<Employee> employees);
        void BindDepartments(IEnumerable<string> departments);

    }

    public class DepartMentSelectedEventArgs : EventArgs
    {
        public string Department { get; private set; }
        public DepartMentSelectedEventArgs(string department)
        {
            this.Department = department;
        }
    }

EmployeeSearchPresenter

 public class EmployeeSearchPresenter
    {
        public IEmployeeSearchView View { get; private set; }
        public EmployeeRepository Repository { get; private set; }

        public EmployeeSearchPresenter(IEmployeeSearchView view)
        {
            this.View = view;
            this.Repository = new EmployeeRepository();
            view.DepartmentSelected += view_DepartmentSelected;
        }

        public void Initialize()
        {
            var employees = this.Repository.GetEmployees();
            this.View.BindEmployees(employees);
            string[] departments = new string[] { "銷售部", "人事部", "IT部" };
            this.View.BindDepartments(departments);
        }

        void view_DepartmentSelected(object sender, DepartMentSelectedEventArgs e)
        {
            string department = e.Department;
            var employees = Repository.GetEmployees(department);
            this.View.BindEmployees(employees);
        }
    }

Web

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="Chaper1SC.WebForm1" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div id="page">
            <div style="text-align: center; clear: both">
                請選擇部門:<asp:DropDownList ID="dpDownListDepartments" runat="server"></asp:DropDownList><asp:Button Text="查詢" runat="server" OnClick="Unnamed_Click" />
            </div>
            <div>
                <asp:GridView ID="GvEmployees" runat="server" AutoGenerateColumns="false" Width="100%">
                    <Columns>
                        <asp:BoundField DataField="Name" HeaderText="姓名" />
                        <asp:BoundField DataField="Gender" HeaderText="性別" />
                        <asp:BoundField DataField="BirthDate" HeaderText="出生日期" DataFormatString="{0:dd/MM/yy}" />
                        <asp:BoundField DataField="Gender" HeaderText="性別" />
                    </Columns>
                </asp:GridView>
            </div>
        </div>
    </form>
</body>
</html>

 

 public partial class WebForm1 : System.Web.UI.Page, IEmployeeSearchView { public event EventHandler<DepartMentSelectedEventArgs> DepartmentSelected; public EmployeeSearchPresenter Presenter { get; private set; } public WebForm1() { this.Presenter = new EmployeeSearchPresenter(this); } protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { this.Presenter.Initialize(); } } public void BindEmployees(IEnumerable<Employee> employees) { this.GvEmployees.DataSource = employees; this.GvEmployees.DataBind(); } public void BindDepartments(IEnumerable<string> departments) { this.dpDownListDepartments.DataSource = departments; this.dpDownListDepartments.DataBind(); } protected void Unnamed_Click(object sender, EventArgs e) { string deparment = this.dpDownListDepartments.SelectedValue; DepartMentSelectedEventArgs args = new DepartMentSelectedEventArgs(deparment); if (null != DepartmentSelected) { DepartmentSelected(sender, args); } } }