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Silverlight 5 Beta新特性[5]隐式模板支持
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繼續(xù)更新Silverlight 5 Beta新特性.在Silverlight 5 BEta更新出來新特性中有一些是WPF已經(jīng)存在的影子.類似前面提到的多窗體[Multiple Window Support].其實很多熟悉WPF同學(xué)應(yīng)該能看到隱式模板[Implicit DataTemplates]也是借鑒WPF而來.Silverlight 4中DataTemplate在非UI項實現(xiàn)數(shù)據(jù)綁定模板可以多處重用.大大增加數(shù)據(jù)顯示多樣性提高重用的效率.當(dāng)然在Silverlight 5 Beta增加了Implicit DataTemplate隱式模板.提供一些新的功能:
Silverlight 5 Implicit DataTemplate:
[1]ContentPresenter的DataTemplates可以選擇基于某個數(shù)據(jù)類型進(jìn)行相關(guān)聯(lián)綁定
[2]隱式定義DataTemplates
[3]當(dāng)數(shù)據(jù)源DataContent發(fā)生變化時.動態(tài)更新的ContentPresenter DataTemplate
[4]在適當(dāng)范圍啟用的DataTemplates? |
類似我們現(xiàn)在定義一項需求:星級酒店推出系統(tǒng)中包含多個服務(wù):RoomService[客房服務(wù)]/Communication[外接服務(wù)]當(dāng)我們把服務(wù)綁定UI上供給用戶選擇時通常采用DataTemplate方式進(jìn)行綁定呈現(xiàn).這時一種簡單通用的方式.定義服務(wù)的實體類:
public?class?Room??? ????{??? ????????public?string?RoomId?{?get;?set;?}??? ????????public?string?RoomName?{?get;?set;?}??? ????????public?string?RoomType?{?get;?set;?}??? ????}??? ???? ????public?class?RoomService?:Room??? ????{?? ????????public?string?ServiceId?{?get;?set;?}?? ????????public?string?ServiceName?{?get;?set;?}?? ????????public?double?ServicePrice?{?get;?set;?}?? ????????public?DateTime?ServiceDate?{?get;?set;?}?? ????}?? ?????public?class?RoomCommunication?:?Room?? ????{?? ????????public?string?CommClientID?{?get;?set;?}?? ????????public?int?CommSpyCounter?{?get;?set;?}?? ????}? 模擬提供數(shù)據(jù)源:
public?class?VipRoom_Service??? ????{??? ????????public?static?IList<Room>?GetRoomServiceDataRecord()??? ????????{??? ????????????List<Room>?getDataRoomService?=?new?List<Room>();??? ????????????getDataRoomService.Add(?new?Room?{??RoomName="StandBy_Phone_Convert"});??? ????????????getDataRoomService.Add(?new?RoomService()?{?RoomName?=?"DUIUser_DataType_Room"});??? ????????????getDataRoomService.Add(?new?RoomService()?{?RoomName?=?"VIPService_DataType_Room"});??? ????????????getDataRoomService.Add(?new?RoomCommunication()?{?RoomName?=?"Communication_Client_Room"?});?? ????????????return?getDataRoomService;?? ????????}?? ????}? 定義需要數(shù)據(jù)綁定ViewModel：
public?class?RoomService_ViewModel?:INotifyPropertyChanged??? ?????{??? ?????????public?event?PropertyChangedEventHandler?PropertyChanged;??? ?????? ?????????public?ObservableCollection<Room>?serviceList=new?ObservableCollection<Room>();??? ?????????public?ObservableCollection<Room>?ServiceList??? ?????????{??? ?????????????get?{return?this.serviceList;?}??? ?????????????set?{this.serviceList?=?value;?}?? ?????????}?? ???? ?????????public?void?SpiltHandleBaseDataList()?? ?????????{?? ?????????????if?(this.serviceList?!=?null)?? ?????????????{?? ?????????????????var?getresult?=?VipRoom_Service.GetRoomServiceDataRecord();?? ?????????????????if?(getresult.Count?>?0)?? ?????????????????{?? ?????????????????????foreach?(Room?getService?in?getresult)?? ?????????????????????????serviceList.Add(getService);?? ?????????????????}?? ?????????????}?? ?????????}?? ??????????????? ?????}? 在UI呈現(xiàn)中做數(shù)據(jù)綁定:
<Grid?x:Name="LayoutRoot"?Background="White"?Margin="30"?>??? ????????<TextBlock?Text="This?Common?DataBind?About?Itemlist!"?FontSize="14"></TextBlock>??? ????????<ListBox???HorizontalAlignment="Center"?VerticalAlignment="Center"??? ???????????????????ItemsSource="{Binding?ServiceList}"???? ???????????????????ScrollViewer.VerticalScrollBarVisibility="Visible"??? ???????????????????Margin="167,47,172,112"?Width="401"?Height="181"></ListBox>??? ???? ????</Grid>? 這種方式很簡單直接把需要所有服務(wù)主題提供了給了用戶.:
但是系統(tǒng)需求發(fā)生變化后 我們需要在酒店服務(wù)系統(tǒng)需要提供訂飛機(jī)票服務(wù)時.你會發(fā)現(xiàn)這種方式呈現(xiàn)使我們的DataBinding的數(shù)據(jù)源發(fā)生變化.在代碼改動代價上前段UI和后臺數(shù)據(jù)綁定都需要修改.這讓人情何以堪.而今天提到Silverlight 5 Beta中隱式模板則徹底解決這個問題.
當(dāng)我們在同一個數(shù)據(jù)加入N數(shù)據(jù)服務(wù)實體對象[存在FirstEntity/SecendEntity/ThreeEntit…N個] 因此我們需要要更加智能化.在數(shù)據(jù)源發(fā)生變動后.前段綁定數(shù)據(jù)UI能夠根據(jù)數(shù)據(jù)源來進(jìn)行自動識別綁定.而這就是Implicit Template隱式模板所做的工作.定義Template:
<UserControl.Resources>??? ?????????<DataTemplate?DataType="model:Room">??? ?????????????<TextBlock?Text="{Binding?RoomName}"?/>??? ?????????</DataTemplate>??? ?????????<DataTemplate?DataType="model:RoomService">??? ?????????????<TextBlock?Text="{Binding?ServiceName}"?/>??? ?????????</DataTemplate>??? ?????????<DataTemplate?DataType="model:RoomCommunication">??? ?????????????<TextBlock?Text="{Binding?CommSpyCounter}"?/>?? ?????????</DataTemplate>?? ?????</UserControl.Resources>? 做了如上綁定.則無需修改后臺數(shù)據(jù)綁定.當(dāng)數(shù)據(jù)發(fā)生變更時依然在前臺UI會根據(jù)DataContent數(shù)據(jù)綁定服務(wù)實體對象[FirstEntity/SecondEntity/ThreeEntity]數(shù)據(jù)類型時則會使用定義DataTemplate模板中綁定相同數(shù)據(jù)類型的模板執(zhí)行.這種方式很方便解決與某個數(shù)據(jù)類型進(jìn)行直接關(guān)聯(lián)而非統(tǒng)一的DataContent.另外一個問題數(shù)據(jù)發(fā)生改變動態(tài)更新使用對應(yīng)DataTemplate.
數(shù)據(jù)模板是很好的方式來規(guī)范應(yīng)用程序中數(shù)據(jù)綁定的格式。有了它們，可能會發(fā)現(xiàn)自己重新思考如何著手重用樣式和格式，可能使用更多的內(nèi)容較少的直接控制和應(yīng)用的樣式.
轉(zhuǎn)載于:https://blog.51cto.com/chenkai/763591
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