此篇博文基于《silverlight4数据与通信之WebClient详解 silverlight4版》，查看请请点击这里
这里用上一篇文章用过的示例，只不过稍微做一点小的改动，使用 WebRequest 提交书籍编号数据，并根据书籍号返回价格信息。
<TextBlock x:Name="lblPrice" Text="价格：" Foreground="White"
HorizontalAlignment="Left" VerticalAlignment="Center"
Margin="20 0 0 0"></TextBlock>
</Border>
</Grid> <Grid.RowDefinitions>
<RowDefinition Height="40"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="40"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition></ColumnDefinition>
</Grid.ColumnDefinitions>
<Border Grid.Row="0" Grid.Column="0" CornerRadius="15"
Width="240" Height="36"
Margin="20 0 0 0" HorizontalAlignment="Left">
<TextBlock Text="书籍列表" Foreground="White"
HorizontalAlignment="Left" VerticalAlignment="Center"
Margin="20 0 0 0"></TextBlock>
</Border>
<ListBox x:Name="Books" Grid.Row="1" Margin="40 10 10 10"
SelectionChanged="Books_SelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding Name}" Height="32"></TextBlock>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Border Grid.Row="2" Grid.Column="0" CornerRadius="15"
Width="240" Height="36" Background="Orange"
Margin="20 0 0 0" HorizontalAlignment="Left"> <Grid Background="#46461F">
编写 HttpHandler，注意我使用了 context.Request.Form["No"]，在后面我们将使用 WebRequest
在 RequestReady 方法中将数据写入请求流：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace sample.Web
{
/// <summary>
/// BookHandler2 的摘要说明
/// </summary>
public class BookHandler2 : IHttpHandler
{
public static readonly string[] PriceList = new string[] {
"66.00",
"78.30",
"56.50",
"28.80",
"77.00"
};
public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = "text/plain";
context.Response.Write(PriceList[Int32.Parse(context.Request.Form["No"])]);
}
public bool IsReusable
{
get
{
return false;
}
}
}
}
在界面加载时绑定书籍列表
private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
List<BookClass> books = new List<BookClass>()
{
new BookClass("Professional ASP.NET 3.5"),
new BookClass("ASP.NET AJAX In Action"),
new BookClass("Silverlight In Action"),
new BookClass("ASP.NET 3.5 Unleashed"),
new BookClass("Introducing Microsoft ASP.NET AJAX")
};
Books.ItemsSource = books;
}
接下来在 SelectionChanged 事件中实现用户选择书籍时，我们使用 WebRequest 提交书籍编号，并且
获得价格数据，仍然采用异步模式，提供 RequestReady和 ResponseReady 两个回调函数：
private string bookNo;
private void Books_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
bookNo = Books.SelectedIndex.ToString();
//端口可根据自己的情况随便更改
Uri endpoint = new Uri(String.Format("http://localhost:80/BookHandler2.ashx"));
WebRequest request = WebRequest.Create(endpoint);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.BeginGetRequestStream(new AsyncCallback(RequestReady), request);
// request.BeginGetResponse(new AsyncCallback(ResponseReady), request);
}
实现 RequestReady 方法，将书籍的编号写入请求流中。要注意添加System.IO命名空间。
void RequestReady(IAsyncResult asyncResult)
{
WebRequest request = asyncResult.AsyncState as WebRequest;
Stream requestStream = request.EndGetRequestStream(asyncResult);
using (StreamWriter writer = new StreamWriter(requestStream))
{
writer.Write(String.Format("No={0}", bookNo));
writer.Flush();
}
request.BeginGetResponse(new AsyncCallback(ResponseReady), request);
}
实现 ResponseReady 方法，显示返回的结果。
void ResponseReady(IAsyncResult asyncResult)
{
WebRequest request = asyncResult.AsyncState as WebRequest;
WebResponse response = request.EndGetResponse(asyncResult);
using (Stream responseStream = response.GetResponseStream())
{
StreamReader reader = new StreamReader(responseStream);
// lblPrice.Text = "价格：" + reader.ReadToEnd();
//lblPrice.Dispatcher.BeginInvoke(new UpdatePriceDelegate(UpdatePrice), reader.ReadToEnd());
//‘charleslau’的方法，可以运行
string price = reader.ReadToEnd();
if (this.lblPrice.CheckAccess())
{
this.lblPrice.Text = "价格:" + price;
}
else
{
this.Dispatcher.BeginInvoke(new UIContextChangedEventHandler(UIContextChanged), price);
}
}
}
public delegate void UIContextChangedEventHandler(object state);
private void UIContextChanged(object state)
{
this.lblPrice.Text = "价格:" + (String)state;
}
至此，大功告成，可以访问了，效果参见上一篇博文，文中有很多注释的地方，那是我参考的实例是silverlight2beta版测试通过的，在silverlight4中有些许不同，我已经做了修改，代码测试可以通过。下面附加后台完整代码
完整后台代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.IO;
namespace sample
{
public partial class s13 : UserControl
{
public s13()
{
InitializeComponent();
}
private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
List<BookClass> books = new List<BookClass>()
{
new BookClass("Professional ASP.NET 3.5"),
new BookClass("ASP.NET AJAX In Action"),
new BookClass("Silverlight In Action"),
new BookClass("ASP.NET 3.5 Unleashed"),
new BookClass("Introducing Microsoft ASP.NET AJAX")
};
Books.ItemsSource = books;
}
private string bookNo;
private void Books_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
bookNo = Books.SelectedIndex.ToString();
//端口可根据自己的情况随便更改
Uri endpoint = new Uri(String.Format("http://localhost:80/BookHandler2.ashx"));
WebRequest request = WebRequest.Create(endpoint);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.BeginGetRequestStream(new AsyncCallback(RequestReady), request);
// request.BeginGetResponse(new AsyncCallback(ResponseReady), request);
}
void RequestReady(IAsyncResult asyncResult)
{
WebRequest request = asyncResult.AsyncState as WebRequest;
Stream requestStream = request.EndGetRequestStream(asyncResult);
using (StreamWriter writer = new StreamWriter(requestStream))
{
writer.Write(String.Format("No={0}", bookNo));
writer.Flush();
}
request.BeginGetResponse(new AsyncCallback(ResponseReady), request);
}
void ResponseReady(IAsyncResult asyncResult)
{
WebRequest request = asyncResult.AsyncState as WebRequest;
WebResponse response = request.EndGetResponse(asyncResult);
using (Stream responseStream = response.GetResponseStream())
{
StreamReader reader = new StreamReader(responseStream);
// lblPrice.Text = "价格：" + reader.ReadToEnd();
//lblPrice.Dispatcher.BeginInvoke(new UpdatePriceDelegate(UpdatePrice), reader.ReadToEnd());
//‘charleslau’的方法，可以运行
string price = reader.ReadToEnd();
if (this.lblPrice.CheckAccess())
{
this.lblPrice.Text = "价格:" + price;
}
else
{
this.Dispatcher.BeginInvoke(new UIContextChangedEventHandler(UIContextChanged), price);
}
}
}
public delegate void UIContextChangedEventHandler(object state);
private void UIContextChanged(object state)
{
this.lblPrice.Text = "价格:" + (String)state;
}
//private void UpdatePrice(string price)
//{
// lblPrice.Text = "price:" + price;
//}
//private delegate void UpdatePriceDelegate(string price);
}
}
感谢李老师和回帖的前辈，我对数据通信知之甚少，如有纰漏，敬请指出