PersistenceContext.java

package com.yourssu.jpa;

import java.util.HashMap;
import java.util.Map;

public class PersistenceContext<T, ID> {
    private final Map<ID, T> entityMap = new HashMap<>();
    private final Map<ID, T> snapshotMap = new HashMap<>();


    public void merge() {
        for (ID id : entityMap.keySet()) {
            T instance = entityMap.get(id);
            T original = snapshotMap.get(id);

            if (original == null) {
                System.out.println("DB에 저장되었습니다. " + instance);
                RealDB.push(id, instance);
                continue;
            }

            if (original.equals(instance)) {
                continue;
            }
            System.out.println("DB에 저장되었습니다. " + instance);
            RealDB.push(id, instance);
        }
    }

    public void save(ID id, T instance) {
        System.out.println("영속성 컨텍스트에 저장되었습니다. " + instance);
        entityMap.put(id, instance);
    }
}