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精进不休 .NET 4.0 (6) - ADO.NET Data Services 1.5 新特性

2010-06-11 09:02 549 查看

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[align=center]精进不休 .NET 4.0 (6) - ADO.NET Data Services 1.5 新特性[/align]

作者：webabcd

介绍
ADO.NET Data Services 1.5 的新增功能
支持服务端的 RowCount - 获取指定实体集合的成员数（只返回一个整型值，而不会返回实体集合）
支持服务端的分页 - 服务端可以返回分页后的数据，并且在其中还可以包含全部数据总数
支持服务端的 Select - 返回的结果只包括 Select 的字段
支持大数据传输 BLOB（binary large object）
支持自定义数据服务

示例
1、服务端 RowCount 的 Demo
MyDataService.svc.cs

代码

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 DataAccess.DataServices.Service
{
    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]
    public class MyDataService : DataService<MyEntity.AdventureWorksEntities>
    {
        public static void InitializeService(DataServiceConfiguration config)
        {
            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
            config.SetEntitySetAccessRule("Products", EntitySetRights.All);

            // SetEntitySetPageSize(string name, int size) - 新增的方法。用于提供分页后的数据
            //     string name - 指定需要用于分页的实体集合
            //     int size - 分页的页大小
            config.SetEntitySetPageSize("Products", 5);
        }
    }
}

RowCount.aspx.cs

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace DataAccess.DataServices
{
    public partial class RowCount : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            MyDataServiceProxy.AdventureWorksEntities context = new MyDataServiceProxy.AdventureWorksEntities(new Uri("http://localhost:9046/DataServices/Service/MyDataService.svc/"));

            // 支持服务端的 RowCount - 获取指定实体集合的成员数（只返回一个整型值，而不会返回实体集合）
            var productCount = context.Products.Count();
            Response.Write(productCount.ToString());
        }
    }
}

/*
$count - 返回 RowCount，即对应集合的成员数（只返回一个整型值，而不会返回实体集合） http://localhost:9046/DataServices/Service/MyDataService.svc/Products/$count
$inlinecount=none - 只返回实体集合（分页后的数据） http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=none
$inlinecount=allpages - 在返回实体集合的基础上（分页后的数据），其中还会包括一个实体集合成员数（分页前的数据）的字段 http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=allpages */

2、服务端分页的 Demo
MyDataService.svc.cs

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace DataAccess.DataServices
{
    public partial class Paging : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            MyDataServiceProxy.AdventureWorksEntities context = new MyDataServiceProxy.AdventureWorksEntities(new Uri("http://localhost:9046/DataServices/Service/MyDataService.svc/"));

            // 支持服务端的分页 - 服务端可以返回分页后的数据，并且在其中还可以包含全部数据总数
            //     服务端代码：config.SetEntitySetPageSize("Products", 5); 表示每页最多 5 条数据
            //     客户端代码：通过 Skip() 方法来控制需要跳过的记录数
            var products = context.Products.Skip(10);

            foreach (var product in products)
            {
                Response.Write(product.ProductID.ToString() + "<br />");
            }
        }
    }
}

/*
$skip=[int] - 指定需要跳过的记录数 http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$skip=10
$inlinecount=none - 只返回实体集合（分页后的数据） http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=none
$inlinecount=allpages - 在返回实体集合的基础上（分页后的数据），其中还会包括一个实体集合成员数（分页前的数据）的字段 http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=allpages */

3、服务端 Select 的 Demo
MyDataService.svc.cs

代码

/*
ADO.NET Data Services 1.5 - 新增了对大数据传输 BLOB（binary large object）的支持
需要在概念模型（ConceptualModels）中的相关实体上增加属性“m:HasStream="true" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata"”
*/

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;

using System.IO;

namespace DataAccess.DataServices.Service
{
    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]
    public class BLOBService : DataService<MyEntity.AdventureWorksEntities>, IServiceProvider
    {
        public static void InitializeService(DataServiceConfiguration config)
        {
            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
            config.SetEntitySetAccessRule("Products", EntitySetRights.All);
        }

        public object GetService(Type serviceType)
        {
            if (serviceType != typeof(System.Data.Services.Providers.IDataServiceStreamProvider))
                return null;

            // 调用服务的时候，如果指定了需要流式传输大数据对象，则通过我们自定义的流式文件传输对象去处理
            return new ProductPhotoStreamProvider();
        }
    }

    /// <summary>
    /// 自定义的一个流式文件传输类，需要实现 System.Data.Services.Providers.IDataServiceStreamProvider 接口
    /// </summary>
    public class ProductPhotoStreamProvider : System.Data.Services.Providers.IDataServiceStreamProvider
    {
        /// <summary>
        /// 获取流。将某个实体的某个属性以流类型的方式返回
        /// </summary>
        /// <param name="entity">相关的实体</param>
        /// <param name="operationContext">当前数据服务请求的上下文</param>
        /// <returns></returns>
        public Stream GetReadStream(object entity, string etag, bool? checkETagForEquality, DataServiceOperationContext operationContext)
        {
            if (entity as MyEntity.Product == null)
                return null;

            int productId = (entity as MyEntity.Product).ProductID;

            using (var context = new MyEntity.AdventureWorksEntities())
            {
                var product = context.Products.First(p => p.ProductID == productId);
                var stream = new MemoryStream(product.ThumbNailPhoto);
                return stream;
            }
        }

        public Uri GetReadStreamUri(object entity, DataServiceOperationContext operationContext)
        {
            return null;
        }

        // 流的内容类型
        public string GetStreamContentType(object entity, DataServiceOperationContext operationContext)
        {
            return "image/jpeg";
        }

        public string GetStreamETag(object entity, DataServiceOperationContext operationContext)
        {
            return null;
        }

        // 流的缓冲区大小
        public int StreamBufferSize
        {
            get { return 64; }
        }

        public void DeleteStream(object entity, DataServiceOperationContext operationContext)
        {
            throw new NotImplementedException();
        }

        public System.IO.Stream GetWriteStream(object entity, string etag, bool? checkETagForEquality, DataServiceOperationContext operationContext)
        {
            throw new NotImplementedException();
        }

        public string ResolveType(string entitySetName, DataServiceOperationContext operationContext)
        {
            throw new NotImplementedException();
        }
    }
}

BLOB.aspx

代码

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true"
    CodeBehind="BLOB.aspx.cs" Inherits="DataAccess.DataServices.BLOB" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">

    

    
    <img src="http://localhost:9046/DataServices/Service/BLOBService.svc/Products(714)/$value" alt="image" />

</asp:Content>

5、自定义数据服务的 Demo
CustomDataService.svc.cs

代码

/*
ADO.NET Data Services 1.5 - 新增了对自定义数据服务的支持
*/

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 DataAccess.DataServices.Service
{
    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]
    public class CustomDataService : DataService<OrderContext>
    {
        public static void InitializeService(DataServiceConfiguration config)
        {
            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
            config.SetEntitySetAccessRule("Orders", EntitySetRights.All);
            config.SetEntitySetAccessRule("Products", EntitySetRights.All);
        }
    }

    /// <summary>
    /// 数据上下文
    /// </summary>
    public class OrderContext
    {
        static List<Order> _orders;
        static List<Product> _products;
        static OrderContext()
        {
            _orders = new List<Order>
            {
                new Order { OrderId = 0, Customer="webabcd"},
                new Order { OrderId = 1, Customer="webabcdefg"}
            };

            _products = new List<Product>
            {
                new Product { ProductId = 0, ProductName="wii", Price=100 },
                new Product { ProductId = 1, ProductName="xbox360", Price=200 },
                new Product { ProductId = 2, ProductName="ps3", Price = 300 },
                new Product { ProductId = 3, ProductName="nds", Price=50 },
                new Product { ProductId = 4, ProductName="psp", Price=100 }
            };

            _orders[0].Items.Add(_products[0]);
            _orders[0].Items.Add(_products[1]);

            _orders[1].Items.Add(_products[2]);
            _orders[1].Items.Add(_products[3]);
            _orders[1].Items.Add(_products[4]);
        }

        public IQueryable<Order> Orders
        {
            get { return _orders.AsQueryable<Order>(); }
        }

        public IQueryable<Product> Products
        {
            get { return _products.AsQueryable<Product>(); }
        }
    }

    /*
     * DataServiceKeyAttribute() - 指定主键字段
     * EntityPropertyMapping() - 实体属性到 ATOM 字段的映射，以便生成一个友好格式的 Feed
     */
    [EntityPropertyMapping("Customer", SyndicationItemProperty.AuthorName, SyndicationTextContentKind.Plaintext, true)]
    [DataServiceKeyAttribute("OrderId")]
    public class Order
    {
        public int OrderId { get; set; }
        public string Customer { get; set; }

        private List<Product> _items;
        public List<Product> Items
        {
            get
            {
                if (_items == null)
                    _items = new List<Product>();

                return _items;
            }
            set
            {
                _items = value;
            }
        }
    }

    [DataServiceKeyAttribute("ProductId")]
    public class Product
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public int Price { get; set; }
    }
}

CustomDataService.aspx.cs

代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace DataAccess.DataServices
{
    public partial class CustomDataService : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            // 使用自定义数据服务提供的服务
            CustomDataServiceProxy.OrderContext context = new CustomDataServiceProxy.OrderContext(new Uri("http://localhost:9046/DataServices/Service/CustomDataService.svc/"));

            var orders = context.Orders;

            foreach (var order in orders)
            {
                Response.Write(order.OrderId.ToString() + "<br />");
            }
        }
    }
}

注：
以 URI 语法的方式查询 ADO.NET 数据服务的形式如下： http:// href="/[ServiceName]/[EntityName]/[NavigationOptions]?[QueryOptions]
详细语法参看 MSDN

OK
[url=http://cid-ebc0a6c186317ea6.skydrive.live.com/self.aspx/Share/VS2010.rar][源码下载]" target=_blank>/[ServiceName]/[EntityName]/[NavigationOptions]?[QueryOptions]
详细语法参看 MSDN

OK
[url=http://cid-ebc0a6c186317ea6.skydrive.live.com/self.aspx/Share/VS2010.rar][源码下载]

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