Design Mode learning notes-Template Method

Overview:

Template Method (templatemethod): definesAlgorithmAnd delay some steps to the subclass.

Templatemethod allows the subclass to redefine certain steps of an algorithm without changing the structure of an algorithm.

Practicality:

1. Implement the unchanged part of an algorithm at one time, and leave the variable behavior to the subclass for implementation.

2. Public behaviors in each subclass should be extracted and concentrated in a public class to avoidCodeDuplicate.

First, identify the differences in the existing code and separate the differences into new operations.

Finally, replace these different codes with a template method that calls these new operations.

3. Control subclass Extension

Class diagram:

Structure display code:

1. define abstract parent class

  Abstract     Class  Abstractclass
{
  ///     <Summary>  
  ///  Abstract behavior, which is implemented by sub-classes
  ///     </Summary>  
    Public    Abstract     Void  Primitiveoperation1 ();
  Public     Abstract     Void  Primitiveoperation2 ();

  ///     <Summary>  
  ///  The template method provides a logical framework, but the abstract operations in the template must be implemented by subclass.
 ///     </Summary>  
    Public     Void  Templatemethod ()
{
Primitiveoperation1 ();
Primitiveoperation2 ();
Console. writeline (  ""  );
}
} 

2. Define subclass of the Implementation Algorithm

   Class Concreteclassa: abstractclass
{
  Public     Override     Void  Primitiveoperation1 ()
{
Console. writeline (  "  Method 1 for Class A to abstract the parent class  "  );
}
  Public     Override    Void  Primitiveoperation2 ()
{
Console. writeline (  "  Method 2 for Class A to abstract the parent class  "  );
}
}
  Class  Concreteclassb: abstractclass
{
  Public     Override     Void  Primitiveoperation1 ()
{
Console. writeline ( "  Method 1 for Class B to abstract the parent class  "  );
}
  Public     Override     Void  Primitiveoperation2 ()
{
Console. writeline (  "  Method 2 for Class B to abstract the parent class  "  );
}
} 

3. Client call

  ///     <Summary>  
  ///  Test Template Method
  ///     </Summary>  
    Static     Void  Testtemplatemethod ()
{
Abstractclass C;
C  =    New  Concreteclassa ();
C. templatemethod ();

C  =     New  Concreteclassb ();
C. templatemethod ();
Console. Read ();
} 

Summary:

The template method is the simplest code reuse and encapsulation, which is used in many system libraries to make your system structure more reasonable.