How to use the BeginInvoke and EndInvoke methods in asp.net

BeginInvoke and EndInvoke change a synchronous method to asynchronous execution. The transformation process involves three steps:

· Add a delegate corresponding to the method;
· Add a callback function of the AsyncCallback delegate type (call EndInvoke in the function body to obtain the return value );
· Pass the method parameters, callback functions, and delegate variables to BeginInvoke;

The following is a simple example:

The code is as follows:

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Public class Test { /// <Summary> /// Original method /// </Summary> /// <Returns> </returns> Private int Todo ()     { Return 100;     } /// <Summary> /// Add the delegate corresponding to the method /// </Summary> /// <Returns> </returns> Delegate int TodoHandler (); /// <Summary> /// Add a callback function of the AsyncCallback delegate type /// </Summary> /// <Param name = "ar"> </param> Private void TodoCallback (IAsyncResult ar)     { TodoHandler handler = (TodoHandler) ar. AsyncState; Console. WriteLine (handler. EndInvoke (ar ));     } /// <Summary> /// Call example /// </Summary> Public void InvokeTest ()     { TodoHandler handler = new TodoHandler (Todo ); Handler. BeginInvoke (TodoCallback, handler );     }        }

Refer to the naming methods BeginXXX and EndXXX for many asynchronous classes and make slight changes to the preceding classes:

The code is as follows:

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Public class Test { Public int Todo (int a, int B)     { Return a + B;     } Private delegate int TodoHandler (int a, int B ); Private TodoHandler _ todo = null; Public Test ()     { _ Todo = Todo;     } Public IAsyncResult BeginTodo (int a, int B, AsyncCallback callback, object state)     { Return _ todo. BeginInvoke (a, B, callback, state );     } Public int EndTodo (IAsyncResult ar)     { Return _ todo. EndInvoke (ar );     } } Public class Program { Static void TodoCallback (IAsyncResult ar)     { Test test = (Test) ar. AsyncState; Console. WriteLine (test. EndTodo (ar ));     } Static public void Main (string [] args)     { Test test = new Test (); Test. BeginTodo (2, 3, TodoCallback, test ); Console. ReadKey ();     } }

The BeginTodo method returns the IAsyncResult type, which is called by someone on the Internet:

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Static public void Main (string [] args) { Test test = new Test (); IAsyncResult result = test. BeginTodo (2, 3, null, null ); Console. WriteLine (test. EndTodo (result )); Console. ReadKey (); }