package com.interview.design.pattern.j2ee;

import java.util.ArrayList;
import java.util.List;

/**
 * Created_By: stefanie
 * Date: 14-12-3
 * Time: 下午6:23
 *
 * The Transfer Object pattern is used when we want to pass data with multiple attributes in one shot from client to server.
 * Transfer object is also known as Value Object. Transfer Object is a simple POJO class having getter/setter methods and
 * is serializable so that it can be transferred over the network.
 * It do not have any behavior.
 * Server Side business class normally fetches data from the database and fills the POJO and send it to the client or pass it by value.
 * For client, transfer object is read-only.
 * Client can create its own transfer object and pass it to server to update values in database in one shot.
 *
 * Following are the entities of this type of design pattern，
 * Business Object - Business Service which fills the Transfer Object with data.
 * Transfer Object -Simple POJO, having methods to set/get attributes only.
 * Client - Client either requests or sends the Transfer Object to Business Object.
 */
public class TransferObjectPattern {
    static class StudentVO {
        private String name;
        private int rollNo;

        StudentVO(String name, int rollNo){
            this.name = name;
            this.rollNo = rollNo;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getRollNo() {
            return rollNo;
        }

        public void setRollNo(int rollNo) {
            this.rollNo = rollNo;
        }
    }

    static class StudentBO {

        //list is working as a database
        List<StudentVO> students;

        public StudentBO(){
            students = new ArrayList<StudentVO>();
            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");
        }
    }

    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);
        student.setName("Michael");
        studentBusinessObject.updateStudent(student);

        //get the student
        studentBusinessObject.getStudent(0);
        System.out.println("Student: [RollNo : "
                +student.getRollNo()+", Name : "+student.getName()+" ]");
    }
}