使用ThreadPool来实现线程的复用

雨点打透心脏的1/2处 2021-12-10 11:15 219阅读 0赞

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][] 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  \}

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][] 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 ;  
\}));  
\});  
\}  
\}

转载于:https://www.cnblogs.com/pfs1314/archive/2010/07/05/1771241.html

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