原文:與眾不同 windows phone (29) - Communication（通信）之與 OData 服務通信

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與眾不同 windows phone (29) - Communication（通信）之與 OData 服務通信

作者：webabcd


介紹
與眾不同 windows phone 7.5 (sdk 7.1) 之通信

• 與 OData 服務通信

示例
1、服務端（采用 Northwind 示例數據庫）
NorthwindService.svc.cs

/** 提供 OData 服務，詳細說明請參見 WCF Data Services 的相關文章：http://www.cnblogs.com/webabcd/category/181636.html*/using System; using System.Collections.Generic; using System.Data.Services; using System.Data.Services.Common; using System.Linq; using System.ServiceModel.Web; using System.Web;namespace Web.Communication {// 出現異常時，返回詳細的錯誤信息[System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]public class NorthwindService : DataService<NorthwindEntities>{public static void InitializeService(DataServiceConfiguration config){// 全部實體全部權限config.SetEntitySetAccessRule("*", EntitySetRights.All);// 指定服務所支持的 OData 協議的最大版本config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;}} }

2、客戶端（ViewModel 層）
MyViewModel.cs

/** 調用 OData 服務的 ViewModel 層* * DataServiceCollection<T> - OData 服務的實體數據集合，添加、刪除和更新數據時都會提供通知，繼承自 ObservableCollection<T>* Count - 實體數據集合中的實體數* CollectionChangedCallback - 實體集合更改時調用的委托* EntityChangedCallback - 實體更改時調用的委托* Continuation - 是否還有下一頁數據* LoadAsync(IQueryable<T> query) - 通過指定的查詢異步加載數據* CancelAsyncLoad() - 取消異步加載請求* LoadNextPartialSetAsync() - 加載下一頁數據* Detach() - 停止跟蹤集合中的全部實體* LoadCompleted - 異步數據加載完成后觸發的事件* * * DataServiceState - 服務狀態* Serialize(DataServiceContext context, Dictionary<string, Object> collections) - 序列化 DataServiceContext 對象以及頁面的相關數據* 注：引用 OData 服務后，會自動生成一個繼承自 DataServiceContext 的代理類，如果需要序列化的話，則必須手動為其加上 [System.Runtime.Serialization.DataContract] * Deserialize() - 反序列化，返回 DataServiceState 類型的數據* Context - 相關的 DataServiceContext 對象* RootCollections - 相關的數據* * * 注：* OData 服務的相關查詢參數參見：http://msdn.microsoft.com/en-us/library/gg309461.aspx*/using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes;using System.ComponentModel; using Demo.NorthwindContext; using System.Data.Services.Client; using System.Linq; using System.Collections.Generic;namespace Demo.Communication.ODataClient.ViewModel {public class MyViewModel : INotifyPropertyChanged{// 引用過來的 OData 服務private NorthwindEntities _context;// OData 服務地址private Uri _northwindUri = new Uri("http://localhost:15482/Communication/NorthwindService.svc/");// 相關數據，DataServiceCollection<T> 繼承自 ObservableCollection<T>public DataServiceCollection<Category> Categories { get; private set; }public void LoadData(){_context = new NorthwindEntities(_northwindUri);// 實例化 DataServiceCollection<Category>，并注冊相關事件Categories = new DataServiceCollection<Category>(_context);Categories.LoadCompleted += new EventHandler<LoadCompletedEventArgs>(Categories_LoadCompleted);// 獲取全部 Categories 數據，并且一次請求帶上 Categories 的所有 ProductsDataServiceQuery<Category> query = _context.Categories.Expand("Products");Categories.LoadAsync(query);NotifyPropertyChanged("Categories");}void Categories_LoadCompleted(object sender, LoadCompletedEventArgs e){if (e.Error == null){// 如果服務端有分頁，則繼續獲取直至獲取完全部數據if (Categories.Continuation != null)Categories.LoadNextPartialSetAsync();}else{Deployment.Current.Dispatcher.BeginInvoke(delegate{MessageBox.Show(e.Error.ToString());});}}// 新增產品數據public void AddProduct(Product product){_context.AddToProducts(product);Categories.Single(p => p.CategoryID == product.CategoryID).Products.Add(product);SaveChanges();}// 刪除產品數據public void DeleteProduct(Product product){_context.DeleteObject(product);Categories.Single(p => p.CategoryID == product.CategoryID).Products.Remove(product);SaveChanges();}// 更新產品數據public void UpdateProduct(Product product){_context.UpdateObject(product);SaveChanges();}public void SaveChanges(){// 異步向 OData 服務提交最近的數據變化 _context.BeginSaveChanges(OnChangesSaved, _context);}private void OnChangesSaved(IAsyncResult result){Deployment.Current.Dispatcher.BeginInvoke(delegate{_context = result.AsyncState as NorthwindEntities;try{// 完成數據提交 _context.EndSaveChanges(result);}catch (Exception ex){MessageBox.Show(ex.ToString());}});}// 一個異步獲取數據的例子，此 Demo 沒用到此方法public void GetData(){// 查找 Products 里 ProductID 為 1 的數據var query = _context.CreateQuery<Product>("Products").AddQueryOption("$filter", "ProductID eq 1");// 異步請求 OData 服務query.BeginExecute(p =>{var myQuery = p.AsyncState as DataServiceQuery<Product>;try{// 獲取請求結果var result = myQuery.EndExecute(p).First();// 更新數據 _context.UpdateObject(result);// 將更新后的結果提交到 OData 服務 SaveChanges();}catch (Exception ex){Deployment.Current.Dispatcher.BeginInvoke(delegate{MessageBox.Show(ex.ToString());});}}, query);}// 序列化當前數據，Deactivated 保存此值到應用程序狀態，參見 App.xaml.cspublic string GetState(){var dict = new Dictionary<string, object>();dict["categories"] = Categories;return DataServiceState.Serialize(_context, dict);}// 恢復數據，當從 tombstone 狀態進入 Activated 時，則從應用程序狀態中恢復數據，參見 App.xaml.cspublic void RestoreState(string appState){Dictionary<string, object> dict;if (!string.IsNullOrEmpty(appState)){DataServiceState state = DataServiceState.Deserialize(appState);// 獲取相關數據var context = state.Context as NorthwindEntities;dict = state.RootCollections;DataServiceCollection<Category> categories = dict["Categories"] as DataServiceCollection<Category>;// 恢復相關數據_context = context;Categories = categories;Categories.LoadCompleted += new EventHandler<LoadCompletedEventArgs>(Categories_LoadCompleted);NotifyPropertyChanged("Categories");}}public event PropertyChangedEventHandler PropertyChanged;private void NotifyPropertyChanged(string propertyName){var propertyChanged = PropertyChanged;if (propertyChanged != null)propertyChanged(this, new PropertyChangedEventArgs(propertyName));}} }

3、客戶端（View 層）
App.xaml

<Application x:Class="Demo.App"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"xmlns:odataViewModel="clr-namespace:Demo.Communication.ODataClient.ViewModel"><Application.Resources><odataViewModel:MyViewModel x:Key="ODataViewModel" /></Application.Resources></Application>

App.xaml.cs

private void Application_Activated(object sender, ActivatedEventArgs e){// 從 tombstone 狀態返回，則恢復相關數據，參見：“調用 OData 服務”if (!e.IsApplicationInstancePreserved){if (PhoneApplicationService.Current.State.ContainsKey("categoriesState")){var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;string categoriesState = PhoneApplicationService.Current.State["categoriesState"] as string;vm.RestoreState(categoriesState);}}}private void Application_Deactivated(object sender, DeactivatedEventArgs e){// 保存相關數據，參見：“調用 OData 服務”var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;PhoneApplicationService.Current.State["categoriesState"] = vm.GetState();}

Demo.xaml

<phone:PhoneApplicationPage x:Class="Demo.Communication.ODataClient.Demo"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"FontFamily="{StaticResource PhoneFontFamilyNormal}"FontSize="{StaticResource PhoneFontSizeNormal}"Foreground="{StaticResource PhoneForegroundBrush}"SupportedOrientations="Portrait" Orientation="Portrait"mc:Ignorable="d" d:DesignHeight="696" d:DesignWidth="480"shell:SystemTray.IsVisible="True"DataContext="{Binding Source={StaticResource ODataViewModel}}"xmlns:controls="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls"><phone:PhoneApplicationPage.Resources><DataTemplate x:Key="item"><ListBox ItemsSource="{Binding Products}"><ListBox.ItemTemplate><DataTemplate><Grid Width="460" HorizontalAlignment="Center"><Grid.ColumnDefinitions><ColumnDefinition Width="5*" /><ColumnDefinition Width="5*" /></Grid.ColumnDefinitions><StackPanel Orientation="Horizontal" VerticalAlignment="Center"><TextBlock Text="{Binding ProductName}" /><TextBlock Text="{Binding UnitPrice}" Margin="10 0 0 0" /></StackPanel><StackPanel Orientation="Horizontal" Grid.Column="1" HorizontalAlignment="Right"><Button x:Name="btnUpdate" Content="更新" Click="btnUpdate_Click" /><Button x:Name="btnDelete" Content="刪除" Click="btnDelete_Click" /></StackPanel></Grid></DataTemplate></ListBox.ItemTemplate></ListBox></DataTemplate><DataTemplate x:Key="header"><TextBlock Text="{Binding CategoryName}" /></DataTemplate></phone:PhoneApplicationPage.Resources><Grid x:Name="LayoutRoot" Background="Transparent"><controls:Pivot x:Name="pivot"Title="產品列表" ItemTemplate="{StaticResource item}" HeaderTemplate="{StaticResource header}"ItemsSource="{Binding Categories}"></controls:Pivot></Grid><phone:PhoneApplicationPage.ApplicationBar><shell:ApplicationBar Mode="Default" IsVisible="True"><shell:ApplicationBarIconButton x:Name="btnAd" IconUri="/ApplicationBarDemo/Assets/appbar.add.rest.png" Text="添加" Click="btnAd_Click" /></shell:ApplicationBar></phone:PhoneApplicationPage.ApplicationBar></phone:PhoneApplicationPage>

Demo.xaml.cs

/** 調用 OData 服務的 View 層*/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 Microsoft.Phone.Controls;using Demo.Communication.ODataClient.ViewModel; using Demo.NorthwindContext;namespace Demo.Communication.ODataClient {public partial class Demo : PhoneApplicationPage{public Demo(){InitializeComponent();this.Loaded += new RoutedEventHandler(Demo_Loaded);}void Demo_Loaded(object sender, RoutedEventArgs e){// 加載數據var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;vm.LoadData();}private void btnDelete_Click(object sender, RoutedEventArgs e){var product = (sender as Button).DataContext as Product;// 刪除指定的產品數據var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;vm.DeleteProduct(product);}private void btnUpdate_Click(object sender, RoutedEventArgs e){// 更新指定的產品數據var product = (sender as Button).DataContext as Product;product.UnitPrice = 8.88m;var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;vm.UpdateProduct(product);}private void btnAd_Click(object sender, EventArgs e){// 在指定的類別下添加一個新的產品數據var category = pivot.SelectedItem as Category;Product product = new Product();product.CategoryID = category.CategoryID;product.ProductName = "測試" + new Random().Next(10, 99);product.UnitPrice = 6.66m;product.Discontinued = false;var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;vm.AddProduct(product);}} }

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