使用ThreadPool来实现线程的复用

代码

   
     

    
      
    
       1 
    
      protected
    
       
    
      override
    
       
    
      void
    
       OnLoad(EventArgs e)

    
       2 
    
       {

    
       3 
    
       
    
      base
    
      .OnLoad(e);

    
       4 
    
      

    
       5 
    
       
    
      //
    
      1.同步读取数据

    
       6 
    
       
    
      //
    
      GetCustomers();

    
       7 
    
      

    
       8 
    
       
    
      //
    
      2.异步读取数据
    
      

    
       9 
    
       
    
       BackgroundWorker worker 
    
      =
    
       
    
      new
    
       BackgroundWorker();

    
      10 
    
       
    
      //
    
      picLoading.Visible = true;
    
      

    
      11 
    
       
    
       IsBusy 
    
      =
    
       
    
      true
    
      ;

    
      12 
    
       worker.DoWork 
    
      +=
    
       (obj, arg) 
    
      =>
    
      

    
      13 
    
       {

    
      14 
    
       arg.Result 
    
      =
    
       GetCustomers();

    
      15 
    
       };

    
      16 
    
       worker.RunWorkerCompleted 
    
      +=
    
       (obj, arg) 
    
      =>
    
      

    
      17 
    
       {

    
      18 
    
       BindingSource bs 
    
      =
    
       
    
      new
    
       BindingSource(arg.Result, 
    
      null
    
      );

    
      19 
    
       lstCustomers.DataSource 
    
      =
    
       bs;

    
      20 
    
       lstCustomers.DisplayMember 
    
      =
    
       
    
      "
    
      CompanyName
    
      "
    
      ;

    
      21 
    
       lstCustomers.ValueMember 
    
      =
    
       
    
      "
    
      CustomerID
    
      "
    
      ;

    
      22 
    
      

    
      23 
    
       IsBusy 
    
      =
    
       
    
      false
    
      ;

    
      24 
    
       
    
      //
    
      picLoading.Visible = false;
    
      

    
      25 
    
       
    
       };

    
      26 
    
       worker.RunWorkerAsync();

    
      27 
    
      

    
      28 
    
       }

    
      29 
    
      

    
      30 
    
       
    
      private
    
       
    
      bool
    
       IsBusy

    
      31 
    
       {

    
      32 
    
       
    
      set
    
      

    
      33 
    
       {

    
      34 
    
       picLoading.Visible 
    
      =
    
       value;

    
      35 
    
       }

    
      36 
    
       }
   
     

 

代码

   
     

    
      
    
      private
    
       List
    
      <
    
      CustomerInfo
    
      >
    
       GetCustomers()
 {
 List
    
      <
    
      CustomerInfo
    
      >
    
       result 
    
      =
    
       
    
      new
    
       List
    
      <
    
      CustomerInfo
    
      >
    
      ();

 
    
      using
    
       (SqlConnection conn 
    
      =
    
       
    
      new
    
       SqlConnection(connectionString))
 {
 Thread.Sleep(
    
      5000
    
      );
 
    
      using
    
       (SqlCommand cmd 
    
      =
    
       conn.CreateCommand())
 {
 cmd.CommandText 
    
      =
    
       
    
      "
    
      SELECT CustomerID,CompanyName FROM Customers
    
      "
    
      ;
 conn.Open();
 SqlDataReader reader 
    
      =
    
       cmd.ExecuteReader();
 
    
      while
    
       (reader.Read())
 {
 result.Add(
 
    
      new
    
       CustomerInfo()
 {
 CustomerID 
    
      =
    
       reader.GetString(
    
      0
    
      ),
 CompanyName 
    
      =
    
       reader.GetString(
    
      1
    
      )
 });
 }
 reader.Close();
 conn.Close();

 }
 }
 
    
      return
    
       result;
 }

 
    
      public
    
       
    
      class
    
       CustomerInfo
 {
 
    
      public
    
       
    
      string
    
       CustomerID { 
    
      get
    
      ; 
    
      set
    
      ; }
 
    
      public
    
       
    
      string
    
       CompanyName { 
    
      get
    
      ; 
    
      set
    
      ; }
 }

 
    
      private
    
       
    
      void
    
       lstCustomers_SelectedIndexChanged(
    
      object
    
       sender, EventArgs e)
 {
 
    
      if
    
       (lstCustomers.SelectedIndex 
    
      !=
    
       
    
      -
    
      1
    
      )
 {
 var customerId 
    
      =
    
       ((CustomerInfo)lstCustomers.SelectedItem).CustomerID;
 
    
      //
    
      picLoading.Visible = true;
    
      

    
       IsBusy 
    
      =
    
       
    
      true
    
      ;
 
    
      //
    
      3.使用ThreadPool(线程池）来实现线程的复用
    
      

    
       ThreadPool.QueueUserWorkItem((obj) 
    
      =>
    
      
 {
 var orders 
    
      =
    
       GetOrderByCustomerID(customerId);
 
    
      this
    
      .BeginInvoke(
    
      new
    
       Action(() 
    
      =>
    
      
 {
 dgvOrders.DataSource 
    
      =
    
       orders.Tables[
    
      0
    
      ];
 
    
      //
    
      picLoading.Visible = false;
    
      

    
       IsBusy 
    
      =
    
       
    
      false
    
      ;
 }));
 });
 }
 }