Design Pattern to use when you want apply some common functionality to some specific methods?

Question

I am trying to figure out a design pattern to use (if any exists) to a situation where I would be re-doing some functionality across a bunch of classes. Below is a (simplified) overview of the problem I am facing:

I have some Java code to CREATE, UPDATE, DELETE Student objects, Professor objects, & Staff objects. And every time such an object is either created, deleted, or updated, I want to extract some information about the affected object (such as name, age, id) and notify an external service. So something like:

class StudentDAO {
   public Student createStudent(Student studentToCreate) {
       jdbcTemplate.update(INSERT_SQL, .....);
       //===> extract some info of the student
       //let external service know a student was created....
   }
   public Student deleteStudent(Student studentToDelete) {
       jdbcTemplate.update(DELETE_SQL, .....);
       //===> extract some info of the student
       //let external service know a student was deleted....
   }
   //same thing for update
}

class ProfessortDAO {
   public Professor createProfessor(Professor professorToCreate) {
       jdbcTemplate.update(INSERT_SQL, .....);
       //===> extract some info of the professor
       //let external service know a Professor was created....
   }
   public Student deleteProfessor(Professor professorToDelete) {
       jdbcTemplate.update(DELETE_SQL, .....);
       //===> extract some info of the professor
       //let external service know a professor was deleted....
   }
   //same thing for update
}

//repeat for Staff

The example is bit contrived but assume that Student, Professor, Staff share no common supertype. Is there a way to achieve this functionality without copying and pasting the logic for extracting the info and sending it in all the DAO classes for CREATE, DELETE, UPDATE methods ?

score 1 · Answer 1 · answered Jun 24 '19 at 19:10

You should search for Generic Repository. You can learn more here:

https://www.youtube.com/results?search_query=generic+repository+java

Sample Code:

class Reposiory<T> {
   public T create(T Create) {
       jdbcTemplate.update(INSERT_SQL, .....);
   }
   public T delete(T Delete) {
       jdbcTemplate.update(DELETE_SQL, .....);
   }

}

score 0 · Answer 2 · answered Jun 23 '19 at 16:40

0

Create ReportExternalService interface and add key property, Implement this Interface if the object requires to be notified.

Create one method which takes the parameter as ReportExternalService and use key to report to external service.!

answered Jun 23 '19 at 16:40

Ramesh Kotha

8,266
17
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90

score 0 · Answer 3 · answered Jun 23 '19 at 16:45

0

You can use aspect oriented programming. You can then write a general point cut which matches all your methods where you want to talk to your external server. What is aspect-oriented programming?

answered Jun 23 '19 at 16:45

Willem

992
6
13

score 0 · Answer 4 · answered Jun 23 '19 at 16:46

Not much info to go on but have you considered using generics for a specific type and implementing an interface to define the common information (phone, name, id) you want to access from each type of individual?

You should also be able to pass the operation (DELETE, ADD, UPDATE) as an argument. I would suggest using an enum for that.

Design Pattern to use when you want apply some common functionality to some specific methods?

4 Answers4