原文:

与众不同 windows phone (29) - Communication（通信）之与 OData 服务通信

作者：

介绍

与众不同 windows phone 7.5 (sdk 7.1) 之通信

• 与 OData 服务通信

示例

1、服务端（采用 Northwind 示例数据库）

NorthwindService.svc.cs

/* * 提供 OData 服务，详细说明请参见 WCF Data Services 的相关文章：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{    // 出现异常时，返回详细的错误信息    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]    public class NorthwindService : DataService
     
          {        public static void InitializeService(DataServiceConfiguration config)        {            // 全部实体全部权限            config.SetEntitySetAccessRule("*", EntitySetRights.All);            // 指定服务所支持的 OData 协议的最大版本            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;        }    }}
     

2、客户端（ViewModel 层）

MyViewModel.cs

/* * 调用 OData 服务的 ViewModel 层 *  * DataServiceCollection
     
       - OData 服务的实体数据集合，添加、删除和更新数据时都会提供通知，继承自 ObservableCollection
      
        *     Count - 实体数据集合中的实体数 *     CollectionChangedCallback - 实体集合更改时调用的委托 *     EntityChangedCallback - 实体更改时调用的委托 *     Continuation - 是否还有下一页数据 *     LoadAsync(IQueryable
       
         query) - 通过指定的查询异步加载数据 *     CancelAsyncLoad() - 取消异步加载请求 *     LoadNextPartialSetAsync() - 加载下一页数据 *     Detach() - 停止跟踪集合中的全部实体 *     LoadCompleted - 异步数据加载完成后触发的事件 *      *  * DataServiceState - 服务状态 *     Serialize(DataServiceContext context, Dictionary
        
          collections) - 序列化 DataServiceContext 对象以及页面的相关数据 *         注：引用 OData 服务后，会自动生成一个继承自 DataServiceContext 的代理类，如果需要序列化的话，则必须手动为其加上 [System.Runtime.Serialization.DataContract]  *     Deserialize() - 反序列化，返回 DataServiceState 类型的数据 *     Context - 相关的 DataServiceContext 对象 *     RootCollections - 相关的数据 *  *  * 注： * OData 服务的相关查询参数参见：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    {        // 引用过来的 OData 服务        private NorthwindEntities _context;        // OData 服务地址        private Uri _northwindUri = new Uri("http://localhost:15482/Communication/NorthwindService.svc/");        // 相关数据，DataServiceCollection
         
           继承自 ObservableCollection
          
            public DataServiceCollection
           
             Categories { get; private set; } public void LoadData() { _context = new NorthwindEntities(_northwindUri); // 实例化 DataServiceCollection
            
             ，并注册相关事件 Categories = new DataServiceCollection
             
              (_context); Categories.LoadCompleted += new EventHandler
              
               (Categories_LoadCompleted); // 获取全部 Categories 数据，并且一次请求带上 Categories 的所有 Products DataServiceQuery
               
                 query = _context.Categories.Expand("Products"); Categories.LoadAsync(query); NotifyPropertyChanged("Categories"); } void Categories_LoadCompleted(object sender, LoadCompletedEventArgs e) { if (e.Error == null) { // 如果服务端有分页，则继续获取直至获取完全部数据 if (Categories.Continuation != null) Categories.LoadNextPartialSetAsync(); } else { Deployment.Current.Dispatcher.BeginInvoke(delegate { MessageBox.Show(e.Error.ToString()); }); } } // 新增产品数据 public void AddProduct(Product product) { _context.AddToProducts(product); Categories.Single(p => p.CategoryID == product.CategoryID).Products.Add(product); SaveChanges(); } // 删除产品数据 public void DeleteProduct(Product product) { _context.DeleteObject(product); Categories.Single(p => p.CategoryID == product.CategoryID).Products.Remove(product); SaveChanges(); } // 更新产品数据 public void UpdateProduct(Product product) { _context.UpdateObject(product); SaveChanges(); } public void SaveChanges() { // 异步向 OData 服务提交最近的数据变化 _context.BeginSaveChanges(OnChangesSaved, _context); } private void OnChangesSaved(IAsyncResult result) { Deployment.Current.Dispatcher.BeginInvoke(delegate { _context = result.AsyncState as NorthwindEntities; try { // 完成数据提交 _context.EndSaveChanges(result); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } }); } // 一个异步获取数据的例子，此 Demo 没用到此方法 public void GetData() { // 查找 Products 里 ProductID 为 1 的数据 var query = _context.CreateQuery
                
                 ("Products").AddQueryOption("$filter", "ProductID eq 1"); // 异步请求 OData 服务 query.BeginExecute(p => { var myQuery = p.AsyncState as DataServiceQuery
                 
                  ; try { // 获取请求结果 var result = myQuery.EndExecute(p).First(); // 更新数据 _context.UpdateObject(result); // 将更新后的结果提交到 OData 服务 SaveChanges(); } catch (Exception ex) { Deployment.Current.Dispatcher.BeginInvoke(delegate { MessageBox.Show(ex.ToString()); }); } }, query); } // 序列化当前数据，Deactivated 保存此值到应用程序状态，参见 App.xaml.cs public string GetState() { var dict = new Dictionary
                  
                   (); dict["categories"] = Categories; return DataServiceState.Serialize(_context, dict); } // 恢复数据，当从 tombstone 状态进入 Activated 时，则从应用程序状态中恢复数据，参见 App.xaml.cs public void RestoreState(string appState) { Dictionary
                   
                     dict; if (!string.IsNullOrEmpty(appState)) { DataServiceState state = DataServiceState.Deserialize(appState); // 获取相关数据 var context = state.Context as NorthwindEntities; dict = state.RootCollections; DataServiceCollection
                    
                      categories = dict["Categories"] as DataServiceCollection
                     
                      ; // 恢复相关数据 _context = context; Categories = categories; Categories.LoadCompleted += new EventHandler
                      
                       (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、客户端（View 层）

App.xaml

App.xaml.cs

private void Application_Activated(object sender, ActivatedEventArgs e)        {            // 从 tombstone 状态返回，则恢复相关数据，参见：“调用 OData 服务”            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)        {            // 保存相关数据，参见：“调用 OData 服务”            var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;            PhoneApplicationService.Current.State["categoriesState"] = vm.GetState();        }

Demo.xaml

Demo.xaml.cs

/* * 调用 OData 服务的 View 层 */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)        {            // 加载数据            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;            // 删除指定的产品数据            var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;            vm.DeleteProduct(product);        }        private void btnUpdate_Click(object sender, RoutedEventArgs e)        {            // 更新指定的产品数据            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)        {            // 在指定的类别下添加一个新的产品数据            var category = pivot.SelectedItem as Category;            Product product = new Product();            product.CategoryID = category.CategoryID;            product.ProductName = "测试" + new Random().Next(10, 99);            product.UnitPrice = 6.66m;            product.Discontinued = false;            var vm = App.Current.Resources["ODataViewModel"] as MyViewModel;            vm.AddProduct(product);        }    }}

OK