学习ASP.NET MVC框架揭秘笔记-实例演示：SC模式的应用

实例演示：sc模式的应用

为了对sc模式下的mvp，尤其是该模式下的view和presenter之间的交互方式有一个深刻的认识，我们现在来做一个实例演示。我们采用员工查询的场景，用asp.net web forms来建立这个简单的应用。

我们先来定义员工的数据类型，employee来表示一个员工，有5个属性：id、姓名、性别、出生日期和部门。

 

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;
        }

 

作为包含应用状态和状态操作行为的model，通过如下一个简单的employeerepository类型来体现。表示所有员工列表的数据通过一个静态字段来维护，而getemployees方法返回指定部门的员工列表。如果没有指定筛选部门或者指定的部门字符为空，该方法直接返回所有员工列表。

 

public class employeerepository
    {
        private static ilist employees;
        static employeerepository()
        {
            employees = new list();
            employees.add(new employee("001", "张三", "男",new datetime(1981, 8, 24), "销售部"));
            employees.add(new employee("002", "李四", "女",new datetime(1982, 7, 10), "人事部"));
            employees.add(new employee("003", "王五", "男",new datetime(1981, 9, 21), "人事部"));
        }

        public ienumerable getemployees(string department = "")
        {
            if (string.isnullorempty(department))
            {
                return employees;
            }
            return employees.where(e => e.department == department).toarray();
        }
    }

 

接下来我们看看作为view接口的iemployeeview的定义。该接口定义了bindemployees和binddepartments两个方法，分别用于绑定基于部门列表的dropdownlist和基于员工列表的gridview。除此之外，iemployeeview接口还定义了一个事件departmentselected，该事件会在用户选择了筛选部门之后单机查询按钮时触发。departmentselected事件参数类型为自定义的departmentselectedeventages，属性department表示用户选择的部门。

public interface iemployeeview
    {
        void bindemployees(ienumerable employees);
        void binddepartments(ienumerable departments);
        event eventhandler departmentselected;
    }
public class departmentselectedeventargs : eventargs
    {
        public string department { get; private set; }
        public departmentselectedeventargs(string department)
        {
            this.department = department;
        }
    }

作为mvp三角关系核心的presenter通过employeepresenter表示。里面包含两个属性，一个代表view的只读属性iemployeeview接口 的view，而另一个代表model的只读属性employeerepository对象的repository，两个属性均在构造函数中初始化。

 

public class employeepresenter
    {
        public iemployeeview view { get; private set; }
        public employeerepository repository { get; private set; }

        public employeepresenter(iemployeeview view)
        {
            this.view = view;
            this.repository = new employeerepository();
            this.view.departmentselected += ondepartmentselected;
        }

        public void initialize()
        {
            ienumerable employees = this.repository.getemployees();
            this.view.bindemployees(employees);
            string[] departments = new string[] { "", "销售部", "采购部", "人事部", "it部" };
            this.view.binddepartments(departments);
        }

        protected void ondepartmentselected(object sender,  departmentselectedeventargs args)
        {
            string department = args.department;
            var employees = this.repository.getemployees(department);
            this.view.bindemployees(employees);
        }
    }

 

我们在构造函数中注册了view的departmentselected事件，作为事件处理器的ondepartmentselected方法通过调用repository（即model）得到了用户选择部门下的员工列表，并且绑定到了view上。

下面我们来看看view的web页面。

:dropdownlist cssclass="form-inline" id="dropdownlistdepartments" runat="server">

下面是web页面的后台代码定义，他实现了定义在iemployeeview接口的方法和事件。

public partial class default : system.web.ui.page, iemployeeview
    {
        public employeepresenter presenter { get; private set; }
        public event eventhandler departmentselected;

        public default()
        {
            this.presenter = new employeepresenter(this);
        }

        protected void page_load(object sender, eventargs e)
        {
            if (!this.ispostback)
            {
                this.presenter.initialize();
            }
        }

        protected void buttonsearch_click(object sender, eventargs e)
        {
            string department = this.dropdownlistdepartments.selectedvalue;
            departmentselectedeventargs eventargs = new departmentselectedeventargs(department);
            if (null != departmentselected)
            {
                departmentselected(this, eventargs);
            }
        }

        public void bindemployees(ienumerable employees)
        {
            this.gridviewemployees.datasource = employees;
            this.gridviewemployees.databind();
        }


        public void binddepartments(ienumerable departments)
        {
            this.dropdownlistdepartments.datasource = departments;
            this.dropdownlistdepartments.databind();
        }
    }