(一)前臺代碼:
<Grid x:Name="LayoutRoot" Background="White">
<StackPanel>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
<TextBlock Height="23" Name="textBlock1" Text="編號" Width="34" />
<TextBox Text="{Binding ID,Mode=OneTime}" Name="tbxID" Width="106" Height="27" ></TextBox>
</StackPanel>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
<TextBlock Height="23" Name="textBlock2" Text="書名:" />
<TextBox Text="{Binding Title,Mode=OneWay}" Name="tbxTitle" Width="108" Height="27" ></TextBox>
</StackPanel>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
<TextBlock Height="23" Name="textBlock3" Text="價格:" VerticalAlignment="Top" />
<TextBox Text="{Binding Price,Mode=TwoWay}" Name="tbxPrice" Width="108" Height="27"></TextBox>
</StackPanel>
<StackPanel>
<Button Name="MyButton" Content="通過數據源修改控件的值" Click="MyButton_Click" Width="140" Height="27"></Button>
<Button Content="直接修改控件的值" Height="23" Name="button1" Width="139" Click="button1_Click" />
<Button Content="通過控件修改數據源的值" Height="23" Name="button2" Width="140" Click="button2_Click" />
</StackPanel>
</StackPanel>
</Grid>
(二)後臺代碼
public partial class MainPage : UserControl
{
Book book = new Book();
public MainPage()
{
InitializeComponent();
book.ID = 0;
book.Title = "ASP.NET 開發手冊";
book.Price = 40;
tbxID.DataContext = book;
tbxTitle.DataContext = book;
tbxPrice.DataContext = book;
}
//通過修改數據源修改控件的值
//如果在沒有實現INotifyPropertyChanged接口情況下,OneTime,OneWay,TwoWay三種方式都不能實現數據源更改控件值的場景
//當實現了INotifyPropertyChanged接口情況下,OneWay,TwoWay能實現數據源更改控件值的場景,而OneTime是不能實現的
//因爲OneTime是初始化綁定後,控件和數據源就沒關係了的
//結論:數據源--》控件 的更改就只能用OneWay,TwoWay並且需要實現INotifyPropertyChanged接口
private void MyButton_Click(object sender, RoutedEventArgs e)
{
book.ID = 100;
book.Price = 50;
book.Title = "SL開發手冊";
}
//通過控件修改數據源的值
//因爲ID是OneTime,Title用的是OneWay無論Book是否繼承了INotifyPropertyChanged接口,都無法通過修改控件tbxID,tbxTitle的值來修改數據源的值的
//對於Pirce使用了TwoWay方式,無論Book是否繼承了INotifyPropertyChanged接口,都可以通過修改tbxPrice的值修改數據源的值
//因爲當目標和源有一個發生變化時,TwoWay 綁定既更新目標也更新源
//結論:控件---》數據源,只有使用TwoWay方式纔可以修改數據源(且不需要實現INotifyPropertyChanged接口)
private void button2_Click(object sender, RoutedEventArgs e)
{
MessageBox.Show(book.ID.ToString() + " " + book.Title.ToString() + " " + book.Price.ToString());
}
//直接修改控件的值
//雖然這樣能更改控件Text屬性值,但要進行類型轉換,在這裏都要轉換爲字符串類型
private void button1_Click(object sender, RoutedEventArgs e)
{
tbxID.Text = "100";
tbxPrice.Text = "50";
tbxTitle.Text = "SL開發手冊";
}
}
public class Book:INotifyPropertyChanged
{
private int _id;
public int ID
{
get { return _id; }
set
{
_id = value;
NotifyPropertyChange("ID");
}
}
private string _title;
public string Title
{
get { return _title; }
set
{
_title = value;
NotifyPropertyChange("Title");
}
}
private double _price;
public double Price
{
get { return _price; }
set
{
_price = value;
NotifyPropertyChange("Price");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChange(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
(三)總結:
數據源--》控件 的更改就只能用OneWay,TwoWay並且需要實現INotifyPropertyChanged接口,而控件---》數據源,只有使用TwoWay方式纔可以修改數據源(且不需要實現INotifyPropertyChanged接口)。然而直接更改控件值,雖然這樣能更改控件Text屬性值,但要進行類型轉換,在這裏都要轉換爲字符串類型。所以我們在操作是常用實體來接收參數,而不是直接去控件的值!