背水一战 Windows 10 (25)

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背水一战 Windows 10 (25) - MVVM: 通过 x:Bind 实现 MVVM（不用 Command）　　
作者：webabcd

介绍
背水一战 Windows 10 之 MVVM（Model-View-ViewModel）

• 通过 x:Bind 实现 MVVM（不用 Command）
  

　　
示例
1、Model
MVVM/Model/Product.cs



/*
* Model 层的实体类，如果需要通知则需要实现 INotifyPropertyChanged 接口
*/
using System.ComponentModel;
namespace Windows10.MVVM.Model
{
public class Product : INotifyPropertyChanged
{
public Product()
{
ProductId = 0;
Name = "";
Category = "";
}
private int _productId;
public int ProductId
{
get { return _productId; }
set
{
_productId = value;
RaisePropertyChanged(nameof(ProductId));
}
}
private string _name;
public string Name
{
get { return _name; }
set
{
_name = value;
RaisePropertyChanged(nameof(Name));
}
}
private string _category;
public string Category
{
get { return _category; }
set
{
_category = value;
RaisePropertyChanged(nameof(Category));
}
}

public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
}
}
　　MVVM/Model/ProductDatabase.cs



/*
* Model 层的数据持久化操作（本地或远程）
*
* 本例只是一个演示
*/
using System;
using System.Collections.Generic;
using System.Linq;
namespace Windows10.MVVM.Model
{
public class ProductDatabase
{
private List<Product> _products = null;
public List<Product> GetProducts()
{
if (_products == null)
{
Random random = new Random();
_products = new List<Product>();
for (int i = 0; i < 100; i++)
{
_products.Add
(
new Product
{
ProductId = i,
Name = "Name" + i.ToString().PadLeft(4, '0'),
Category = "Category" + (char)random.Next(65, 91)
}
);
}
}
return _products;
}
public List<Product> GetProducts(string name, string category)
{
return GetProducts().Where(p => p.Name.Contains(name) && p.Category.Contains(category)).ToList();
}
public void Update(Product product)
{
var oldProduct = _products.Single(p => p.ProductId == product.ProductId);
oldProduct = product;
}
public Product Add(string name, string category)
{
Product product = new Product();
product.ProductId = _products.Max(p => p.ProductId) + 1;
product.Name = name;
product.Category = category;
_products.Insert(0, product);
return product;
}
public void Delete(Product product)
{
_products.Remove(product);
}
}
}
　　
2、ViewModel
MVVM/ViewModel2/ProductViewModel.cs



/*
* ViewModel 层
*/
using System.Collections.ObjectModel;
using System.ComponentModel;
using Windows.UI.Xaml;
using Windows10.MVVM.Model;
namespace Windows10.MVVM.ViewModel2
{
public class ProductViewModel : INotifyPropertyChanged
{
// 用于提供 Products 数据
private ObservableCollection<Product> _products;
public ObservableCollection<Product> Products
{
get { return _products; }
set
{
_products = value;
RaisePropertyChanged(nameof(Products));
}
}
// 用于“添加”和“查询”的 Product 对象
private Product _product;
public Product Product
{
get { return _product; }
set
{
_product = value;
RaisePropertyChanged(nameof(Product));
}
}
// 数据库对象
private ProductDatabase _context = null;
public ProductViewModel()
{
_context = new ProductDatabase();
Product = new Product();
Products = new ObservableCollection<Product>(_context.GetProducts());
}

public void GetProducts(object sender, RoutedEventArgs e)
{
// 从 Model 层获取数据
Products = new ObservableCollection<Product>(_context.GetProducts(Product.Name, Product.Category));
}
public void AddProduct(object sender, RoutedEventArgs e)
{
// 在 Model 层添加一条数据
Product newProduct = _context.Add(Product.Name, Product.Category);
// 更新 ViewModel 层数据
Products.Insert(0, newProduct);
}
public void UpdateProduct(object sender, RoutedEventArgs e)
{
Product product = ((FrameworkElement)sender).Tag as Product;
// 更新 ViewModel 层数据
product.Name = product.Name + "U";
product.Category = product.Category + "U";
// 更新 Model 层数据
            _context.Update(product);
}
public void DeleteProduct(object sender, RoutedEventArgs e)
{
Product product = ((FrameworkElement)sender).Tag as Product;
// 更新 Model 层数据
            _context.Delete(product);
// 更新 ViewModel 层数据
            Products.Remove(product);
}

public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
}
}
　　
3、View
MVVM/View/Demo2.xaml



<Page
x:Class="Windows10.MVVM.View.Demo2"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:Windows10.MVVM.View"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:model="using:Windows10.MVVM.Model">
<Grid Background="Transparent">
<StackPanel Margin="10 0 10 10">
<!--
View 层
-->
<!--
本例通过 x:Bind 实现 MVVM（不用 Command）
-->
<ListView Name="listView" ItemsSource="{x:Bind ProductViewModel.Products, Mode=OneWay}" Width="300" Height="300" HorizontalAlignment="Left" VerticalAlignment="Top">
<ListView.ItemTemplate>
<DataTemplate x:DataType="model:Product">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{x:Bind Name, Mode=OneWay}" HorizontalAlignment="Left" />
<TextBlock Text="{x:Bind Category, Mode=OneWay}" HorizontalAlignment="Left" Margin="10 0 0 0" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<StackPanel Orientation="Horizontal" Margin="0 10 0 0">
<TextBlock Text="Name：" VerticalAlignment="Center" />
<TextBox Name="txtName" Text="{x:Bind ProductViewModel.Product.Name, Mode=TwoWay}" Width="100" />
<TextBlock Text="Category：" VerticalAlignment="Center" Margin="20 0 0 0" />
<TextBox Name="txtCategory" Text="{x:Bind ProductViewModel.Product.Category, Mode=TwoWay}" Width="100" />
</StackPanel>
<StackPanel Orientation="Horizontal" Margin="0 10 0 0">
<Button Name="btnSearch" Content="查询" Click="{x:Bind ProductViewModel.GetProducts}" Margin="10 0 0 0" />
<Button Name="btnAdd" Content="添加" Click="{x:Bind ProductViewModel.AddProduct}" Margin="10 0 0 0" />
<Button Name="btnUpdate" Content="更新" Click="{x:Bind ProductViewModel.UpdateProduct}" Tag="{x:Bind listView.SelectedItem, Mode=OneWay}" Margin="10 0 0 0" />
<Button Name="btnDelete" Content="删除" Click="{x:Bind ProductViewModel.DeleteProduct}" Tag="{x:Bind listView.SelectedItem, Mode=OneWay}" Margin="10 0 0 0" />
</StackPanel>
</StackPanel>
</Grid>
</Page>
　　
OK
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