Approach: Modify Complex Data using AOP and Reflection

Question

I have configured my spring Application as below:

 // Spring MVC controller
 @Controller
 HelloController {  

   @ResponseBody
   Student getData() {
    return student from database;
    }
 }

public Class Student {

 @Trim(device = "mob", trim=10)
 @Trim(device = "desktop", trim=100)
 String name ;

 Address address;

}

public class Address {

 @Trim(device = "mob", trim=10 )
 @Trim(device = "desktop", trim=100 )
 String addressInfo

 }

Requirements:

After the Controller returns the Student, do modification of Student object and all complex attributes inside it based on the Annotation, for example if the request was from mobile trim the student name to 10 and so on.

Approaches I can think of:

1. Recursively iterate on fields with annotation and modify fields. Iteration on class fields every time can be hectic, as the class is complex and can nest up to n levels.

2. Create a List of Annotated fields at server start up and when then iterate on this list and apply changes to the target object.

   I am currently struggling with both approachs. So would like to know whether there exists some prebuilt solutions or design patterns to handle such scenarios.

Answer 1

I actually coded the Reflection based approach and created a library some time back.

It uses reflection to identify annotation on fields and then takes the appropriate action based on the input device.

Here is the link for library https://github.com/santoshjoshi/Adaptive-Device-Data-Filtering