Transfer Object Pattern in Java

It is used when we want to pass data with multiple attributes in one shot from client to server. Transfer Object is a simple POJO class having getter/setter methods and is serialized so that it can be transferred over the network. Server Side business class normally fetches data from the database and fills the POJO and sends it to the client or passes it by value. For clients, the transfer object is read-only. The client can create its own transfer object and pass it to the server to update values in the database in one shot.

Following are the entities of this type of design pattern:

Transfer Object Simple POJO having methods to set/get attributes only

Business Object Fills the Transfer Object with data

Client Either requests or sends the Transfer Object to Business Object

Approach:

Step 1: Create a Transfer Object

Step 2: Create a Business Object.

Step 3: Use the StudentBO to demonstrate Transfer Object Design Pattern

Step 4: Verify the output.

Procedure: 

Step 1: Creating a Transfer Object 

Example

// Transfer Object Pattern - Design Pattern

  

// Step 1

// Creating a Transfer Object 

// randomly be named it 'StudentVO.java'

  

// Class StudentVO

public class StudentVO {

    

  // Member variables of class

   private String name;

   private int rollNo;

    

  // Creating a constructor of above class

  StudentVO(String name, int rollNo) {

      

    // This keyword for assignment 

    // to same memory block created

    // for every nae and roll number of student

    this.name = name;

      this.rollNo = rollNo;

   }

    

  // Getting name of student 

   public String getName() {

      return name;

   }

    

  // Setting name of Student 

   public void setName(String name) {

      this.name = name;

   }

    

  // Getting roll number of student 

   public int getRollNo() {

      return rollNo;

   }

    

  // Setting roll number of student 

   public void setRollNo(int rollNo) {

      this.rollNo = rollNo;

   }

}

Step 2: Creating a Business Object

Example

// Transfer Object Pattern - Design Pattern

  

// Step 2

// Creating a Busines object 

// randomly be named it 'StudentBO.java'

  

// Importing List and ArrayList classes of

// java.util package

import java.util.ArrayList;

import java.util.List;

  

// Class StudentBO

public class StudentBO {

      

   // List is working as a database

   List<StudentVO> students;

   public StudentBO() {

   

      students = new ArrayList<StudentVO>();

       

     // Adding custom inputs 

      StudentVO student1 = new StudentVO("Robert",0);

      StudentVO student2 = new StudentVO("John",1);

      students.add(student1);

      students.add(student2);        

   }

    

   public void deleteStudent(StudentVO student) {

      students.remove(student.getRollNo());

      System.out.println("Student: Roll No " + student.getRollNo() + ", deleted from database");

   }

    

   //retrive list of students from the database

   public List<StudentVO> getAllStudents() {

      return students;

   }

    

   public StudentVO getStudent(int rollNo) {

      return students.get(rollNo);

   }

    

   public void updateStudent(StudentVO student) {

      students.get(student.getRollNo()).setName(student.getName());

      System.out.println("Student: Roll No " + student.getRollNo() +", updated in the database");

   }

}

Step 3: Use the StudentBO to demonstrate Transfer Object Design Pattern

Implementation:  List is acting as DB here as shown in demonstrating Transfer Object Design Pattern.

Example

// Transfer Object Pattern - Design Pattern

// Step 3

  

// Use the StudentBO to demonstrate Transfer Object Design Pattern

// randomly be named it 'TransferObjectPatternDemo.java'

  

public class TransferObjectPatternDemo {

    

  // Main driver method

   public static void main(String[] args) {

       

      StudentBO studentBusinessObject = new StudentBO();

        

     // Print all students

      for (StudentVO student : studentBusinessObject.getAllStudents()) {

         System.out.println("Student: [RollNo : " + student.getRollNo() + ", Name : " + student.getName() + " ]");

      }

       

      // Update student

      StudentVO student = studentBusinessObject.getAllStudents().get(0);

       

     // Custom input  

     student.setName("Michael");

      studentBusinessObject.updateStudent(student);

        

     // Getting the student

      student = studentBusinessObject.getStudent(0);

      System.out.println("Student: [RollNo : " + student.getRollNo() + ", Name : " + student.getName() + " ]");

   }

}

Step 4: Verifying output

Student : [RollNo : 0, Name : Robert ]

Student : [RollNo : 1, Name : John ]

Student : Roll No 0, updated in the database

Student : [RollNo : 0, Name : Michael ]