Delegated application instance

Requirement: automatically construct the corresponding request based on the input action parameter.

Go directlyCode.

First define a myrequest class. Sub-classes include addrequest, loadrequest, and deleterequest.

 

Myrequest

  1     Public     Class  Myrequest
  2   {
 3     Public     String  Action {  Get  ;  Private     Set  ;}
  4     //  Public gridpagerparams pager {Get; private set ;}  
 5      
  6     Public  Myrequest ()
  7   {
  8   
  9   }
  10     Public    Virtual     String  MSG ()
  11   {
  12     Return  Action. tostring ();
  13   }
  14   } 

Myrequest defines a virtual method MSG ();

Each subclassAlgorithmDifferent, You can override this method.

The following is the key: myrequestcreator

Myrequestcreator is responsible for determining the parameter action and returning the corresponding request.

 

Myrequestcreator

    Public     Class  Myrequestcreator
{
  Private     Static  Dictionary  <  String , Myrequestcreator. _ newmytype  >  _ Creatordict  =     New  Dictionary  <  String  , Myrequestcreator. _ newmytype  >  ();
  Private     Delegate  Myrequest _ newmytype ();
 Static  Myrequestcreator ()  //  Initialization  
  {
_ Creatordict. Add (  "  Load  "  ,  New  Myrequestcreator. _ newmytype (  Delegate  (){  Return    New  Loadrequest ();}));
_ Creatordict. Add (  "  Add  "  ,  New  Myrequestcreator. _ newmytype (  Delegate  (){  Return     New  Addrequest ();}));  //
  _ Creatordict. Add ( "  Delete  "  ,  New  Myrequestcreator. _ newmytype (  Delegate  (){  Return     New  Myrequest ();}));
}
  Public     Static  Myrequest createhandler ( String  Action)
{
  If  (_ Creatordict. containskey (Action ))
{
Myrequest rethandler  =  _ Creatordict [action]. Invoke ();
  Try  
{
  Return  Rethandler;
}
  Catch  (Exception E)
{
  Throw    New  Exception (  "  Request Processing failed!  "  , E );
}
}
  Return     Null  ;
}
} 

Client call time:

Myrequest request = myrequestcreator. createhandler ("LOAD ");

In this way, you can generate a specific subclass of myrequest and use its function in myrequest mode.

There is no if or case in the whole process. In combination with emit, you can also dynamically Add a subclass of myrequest and register it in myrequestcreator.

More importantly, using this method is much faster than generating an object based on activator. createinstance (typeof (myrequest);, which is close to directly using new object.