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WCF服务中的一个通用类 [复制链接]

csu8263

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发表于 2011-12-20 09:44 |只看该作者 |倒序浏览
WCF的异步服务编程，必须创建一个IAsyncResult的自定义实现：
 
  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Text;
  5. using System.Threading;

  7. class UniversalAsyncResult : IAsyncResult, IDisposable
  8. {
  9.     // 存储回调和状态

  11.     AsyncCallback callback;
  12.     object state;

  14.     // For the implementation of IAsyncResult.AsyncCallback

  16.     volatile ManualResetEvent waithandle;

  18.     // 线程同步对象

  20.     object guard = new object();

  22.     // 完成标志，设置为true就表示完成

  24.     volatile bool complete;

  26.     public UniversalAsyncResult(AsyncCallback callback, object state)
  27.     {
  28.         this.callback = callback;
  29.         this.state = state;
  30.     }

  32.     public void Complete()
  33.     {
  34.         // flag as complete

  36.         complete = true;

  38.         // signal the event object

  40.         if (waithandle != null)
  41.         {
  42.             waithandle.Set();
  43.         }

  45.         // Fire callback to signal the call is complete

  47.         if (callback != null)
  48.         {
  49.             callback(this);
  50.         }
  51.     }

  53.     #region IAsyncResult Members
  54.     public object AsyncState
  55.     {
  56.         get { return state; }
  57.     }

  59.     // Use double check locking for efficient lazy allocation of the event object

  61.     public WaitHandle AsyncWaitHandle
  62.     {
  63.         get
  64.         {
  65.             if (waithandle == null)
  66.             {
  67.                 lock (guard)
  68.                 {
  69.                     if (waithandle == null)
  70.                     {
  71.                         waithandle = new ManualResetEvent(false);

  73.                         if (complete)
  74.                         {
  75.                             waithandle.Set();
  76.                         }
  77.                     }
  78.                 }
  79.             }
  80.             return waithandle;
  81.         }
  82.     }

  84.     public bool CompletedSynchronously
  85.     {
  86.         get { return false; }
  87.     }

  89.     public bool IsCompleted
  90.     {
  91.         get { return complete; }
  92.     }
  93.     #endregion

  95.     #region IDisposable Members
  96.     
  97.     public void Dispose()
  98.     {
  99.         if (waithandle != null)
  100.         {
  101.             waithandle.Close();
  102.         }
  103.     }
  104.     #endregion
  105. }
应用==========>
 
服务端：
  1. using System;
  2. using System.Collections.Generic;
  3. using System.Text;
  4. using System.ServiceModel;
  5. using System.Data.SqlClient;
  6. using System.Data;
  7. using System.Threading;

  9. namespace Service
  10. {
  11.     class Program
  12.     {
  13.         static void Main(string[] args)
  14.         {
  15.             using (ServiceHost host = new ServiceHost(typeof(Service)))
  16.             {
  17.                 host.Open();

  19.                 Console.WriteLine("Async Service Ready ...");
  20.                 Console.ReadLine();
  21.             }
  22.         }
  23.     }

  25.     [ServiceContract]
  26.     interface IGetData
  27.     {
  28.         // This pair of methods are bound together as WCF is aware of the async pattern

  30.         [OperationContract(AsyncPattern=true)]
  31.         IAsyncResult BeginGetData(AsyncCallback cb, object state);
  32.         string[] EndGetData(IAsyncResult iar);
  33.     }

  35.     class Service : IGetData
  36.     {
  37.         SqlCommand cmd;
  38.         SqlConnection conn;
  39.         DataAsyncResult dar;

  41.         // This connection string sets up the connection for asynchronous process which is supported by SQL2005

  43.         static readonly string CONN_STR = @"Server=.\sqlexpress; database=slowdb; integrated security=SSPI; Asynchronous Processing=true";

  45.         // This is the async pattern begin method that is passed a callback from the WCF infrastructure

  47.         public IAsyncResult BeginGetData(AsyncCallback cb, object state)
  48.         {
  49.             // Create own async result type call object to let WCF know when the call has completed and so

  51.             // when it can call the EndGetData method

  53.             dar = new DataAsyncResult(cb, state);

  55.             // Create the connection annd command

  57.             conn = new SqlConnection(CONN_STR);
  58.             cmd = conn.CreateCommand();
  59.             cmd.CommandText = "SlowSproc";
  60.             cmd.CommandType = CommandType.StoredProcedure;

  62.             conn.Open();

  64.             // Process the query asynchronously

  66.             // this will take place using IO completion ports

  68.             // so a thread is not being used while the query is running

  70.             cmd.BeginExecuteReader(Callback, null);

  72.             // return the call object to the WCF infrastructure

  74.             return dar;
  75.         }

  77.         // End method cleans up and sends back the results

  79.         public string[] EndGetData(IAsyncResult iar)
  80.         {
  81.             dar.Dispose();
  82.             return data.ToArray();
  83.         }

  85.         // Called when the async query completes

  87.         void Callback( IAsyncResult iar )
  88.         {
  89.             List<string> results = new List<string>();

  91.             // process the list of results

  93.             using (SqlDataReader reader = cmd.EndExecuteReader(iar))
  94.             {

  96.                 while( reader.Read() )
  97.                 {
  98.                     results.Add((string)reader["val"]);
  99.                 }
  100.             }

  102.             // cache the results

  104.             data = results;

  106.             // clean up the connection which is no longer required

  108.             conn.Dispose();

  110.             // Tell the call object that the call is now complete

  112.             dar.Complete();
  113.         }

  115.         List<string> data;
  116.     }
 客户端：
  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Text;
  5. using Client.ServiceReference;

  7. namespace Client
  8. {
  9.     class Program
  10.     {
  11.         static void Main(string[] args)
  12.         {
  13.             GetDataClient proxy = new GetDataClient();

  15.             string[] res = proxy.GetData();

  17.             foreach (var item in res)
  18.             {
  19.                 Console.WriteLine(item);
  20.             }
  21.         }
  22.     }
  23. }
 
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