INotifyPropertyChanged接口实现的一个小例子（2）

布局代码：

<Grid >
        <TextBox Height="23" Text="{Binding Name}" HorizontalAlignment="Left" Margin="22,12,0,0" Name="txtName" VerticalAlignment="Top" Width="120" />
        <TextBox Height="23" Text="{Binding Age}" HorizontalAlignment="Left" Margin="33,59,0,0" Name="txtAge" VerticalAlignment="Top" Width="120"/>
        <TextBox Height="23" Margin="332,12,76,0" Name="textBox1" VerticalAlignment="Top"  Text="{Binding Path=Value,ElementName=slider1}"/>
        <Slider Margin="200,50,34,191" Name="slider1" Value="{Binding Path=Text,ElementName=textBox1}" />
        <Button Content="Age++" Height="23" HorizontalAlignment="Left" Margin="33,127,0,0" Name="btnAdd" VerticalAlignment="Top" Width="75" Click="btnAdd_Click" />
        <Button Content="显示Age" Height="23" HorizontalAlignment="Left" Margin="145,127,0,0" Name="btnView" VerticalAlignment="Top" Width="75" Click="btnView_Click" />
    </Grid>

 

MainWindow.xaml.cs中代码：

namespace 数据绑定
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private Person p1 = new Person();

       

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            p1.Name = "zhangsan";
            p1.Age = 21;
            txtAge.DataContext = p1;
            txtName.DataContext = p1;
        }

        private void btnAdd_Click(object sender, RoutedEventArgs e)
        {
            p1.Age++;
        }

        private void btnView_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show(p1.Age.ToString());
        }

       

    }
}

Person类中代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;



namespace 数据绑定
{
    class Person :INotifyPropertyChanged
    {
        //public int Age
        //{
        //    get;
        //    set;
        //}
        //public string Name
        //{
        //    get;
        //    set;
        //}
        private int age;
        private string name;
        public event PropertyChangedEventHandler PropertyChanged;
        public int Age
        {
            get
            {
                return age;
            }
            set
            {
                this.age = value;
                if (PropertyChanged != null)
                {
                    PropertyChanged(this, new PropertyChangedEventArgs("Age"));
                }
            }
        }
        public string Name
        {
            get
            {
                return name;
            }
            set
            {
                this.name = value;
                if (PropertyChanged != null)
                {
                    PropertyChanged(this, new PropertyChangedEventArgs("Name"));
                }
            }
        }
      }
}

 

 后记：由于普通对象没有“通知我的属性变了”这么一种机制，所以改变对象的属性界面不会变。但是界面改变是有TextChanged之类的事件的，所以改变界面可以同步修改到对象。
如果要求后台对象的值发生改变界面跟着变，则需要类实现INotifyPropertyChanged接口，并且在属性值变化后触发事件：

      public int Age
        {
            get
            {
                return age;
            }
            set
            {
                this.age = value;
                if (PropertyChanged != null)
                {
                    PropertyChanged(this,
                        new PropertyChangedEventArgs("Age"));
                }
            }
        }

如果说后台对象的值不会变，则没必要实现INotifyPropertyChanged，也能享受界面值变化DataContext对象跟着变的“福利”