在Silverlight2中开发User Control(用户控件)

admin - 2008-6-6 14:15:00

在silverlight 2(Beta1) 中开发用户控件与我们以前在Webform中使用的方式基本上接近．
下面是一个DEMO，用于执行一个简单的查询雇员信息的操作．运行结果如下图所示:

首先我们要新建一个Silverlight Application , 名称为：SearchUserControl
在该项目中添加一个Silverlight User Control , 名称为：EmployeeSearch

然后我们在该用户控件的CS代码中添加一个类用于描述雇员信息，如下：

public class EmployeeInfo
{
public string EmployeeNo { get; set; }
public string EmployeeName { get; set; }
}

另外还有一个EmployeeNameEventArgs类，用于当点击查询时，将要查询的雇员姓名以事件
参数方式传递到Page页面中，如下：

public class EmployeeNameEventArgs : EventArgs
{
public string EmployeeName { get; set; }
}

到这里准备工作就绪，下面是相应的控件xaml代码，请将其粘贴到EmployeeSearch.xaml中:

<Grid x:Name="LayoutRoot" Background="White">
<Grid.RowDefinitions>
<RowDefinition Height="200" />
<RowDefinition Height="100" />
<RowDefinition Height="50" />
</Grid.RowDefinitions>

<ListBox Margin="10" x:Name="EmployeeList"/>

<StackPanel Grid.Row="1" Margin="12">
<TextBlock>输入要查询的名称：</TextBlock>
<TextBox x:Name="Search" Margin="10" Text="james" />
</StackPanel>
<Button Margin ="10" Content="获取Employee信息" Grid.Row="2" Click="OnGetEmployee"
Width="120" />
</Grid>

然后将下面的cs代码复制到EmployeeSearch.xaml.cs中，相关内容参见注释:

public partial class EmployeeSearch : System.Windows.Controls.UserControl
{

#region 使用依赖属性从PAGE页面传参到当前用户控件,详情参见Page.xaml页面
public static DependencyProperty SearchEmployeeNameProperty =
DependencyProperty.Register("SearchEmployeeName", typeof(string),
typeof(EmployeeSearch), null);

public string SearchEmployeeName
{
get
{
return ((string)base.GetValue(SearchEmployeeNameProperty));
}
set
{
base.SetValue(SearchEmployeeNameProperty, value);
}
}
#endregion

/// <summary>
/// 声明查询单击事件
/// </summary>
public event EventHandler<EmployeeNameEventArgs> SearchClick;

public EmployeeSearch()
{
InitializeComponent();
this.Loaded += OnLoaded;
}

void OnLoaded(object sender, RoutedEventArgs e)
{
Search.Text = SearchEmployeeName;
}

void OnGetEmployee(object o, EventArgs e)
{
//当有事件绑定时(参见page.xaml中的 SearchClick="OnSearch" 属性)
if (SearchClick != null)
{
SearchEmployeeName = Search.Text;
//运行绑定的单击事件代码
SearchClick(this, new EmployeeNameEventArgs()
{
EmployeeName = Search.Text
});
}
}

//将ListBox的ItemsSource属性开放给Page页面，以便进行数据绑定
public System.Collections.IEnumerable ItemsSource
{
get
{
return EmployeeList.ItemsSource;
}
set
{
EmployeeList.ItemsSource = value;
}
}
}

这样控件的开发就完成了，下面是在page.xaml中声明并设置这个控件相应属性的代码：

<UserControl x:Class="SearchUserControl.Page"
xmlns="http://schemas.microsoft.com/client/2007"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="400" Height="400" xmlns:local="clr-namespace:SearchUserControl">
<UserControl.Resources>
<local:EmployeeInfo EmployeeName="王五" x:Key="myEmployee" />
</UserControl.Resources>

<StackPanel x:Name="LayoutRoot" Background="White">
<local:EmployeeSearch x:Name="SearchControl" SearchClick="OnSearch"
SearchEmployeeName = "{Binding EmployeeName}"
DataContext = "{StaticResource myEmployee}" />

<TextBlock x:Name="txtEmployeeName" Text="暂无" FontSize="16" Margin="10" TextAlignment="Center" />
</StackPanel>
</UserControl>

其中的xmlns:local="clr-namespace:SearchUserControl"为控件的名空间的引用，类似于我们
以前写用户控件时的：

<%@ Register TagPrefix="" Namespace="" Assembly="" %>

而下面代码即是我们引用该控件并进行属性设置的声明：

<local:EmployeeSearch x:Name="SearchControl" SearchClick="OnSearch"
SearchEmployeeName = "{Binding EmployeeName}"
DataContext = "{StaticResource myEmployee}" />

StaticResource myEmployee会使用本地绑定的静态资源中所指向的数据，如下：

<UserControl.Resources>
<local:EmployeeInfo EmployeeName="王五" x:Key="myEmployee" />
</UserControl.Resources>

这样就会将控件中的搜索框绑定到该初始值（资源）上．

而下面就是实际运行这个控件执行查询操作时CS代码（page.xaml.cs）：

void OnSearch(object sender, EmployeeNameEventArgs e)
{
List<string> employeeList = new List<string>();
foreach (EmployeeInfo en in GetData(e.EmployeeName))
{
employeeList.Add(en.EmployeeNo + " " + en.EmployeeName);
}

SearchControl.ItemsSource = employeeList;

txtEmployeeName.Text = "查询有关 """ + SearchControl.SearchEmployeeName + """ Employee信息";
}

private List<EmployeeInfo> GetData(string value)
{
Dictionary<string, string> employee = new Dictionary<string, string>(){ {"10001", "张三"},
{"10002", "李四"},
{"10003", "王五"},
{"10004", "马六"},
{"10005", "王大麻子"},
{"10006", "王宝强"},
{"10007", "王蛋蛋"},
{"10008", "王五强"}
};

return (from e in employee
where e.Value.Contains(value.Trim())
select new EmployeeInfo
{
EmployeeNo = e.Key,
EmployeeName = e.Value
}).ToList();
}

因为代码比较简单，基本上就是一个linq to object查询，所以就不多做说明了．

附件: silverlight_usercontrol.rar

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