categoryserviceimpl.java

Struts-Hibernate application

/**
 * 
 */
package com.javachap.service.impl;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;

import com.javachap.domain.Category;
import com.javachap.service.CategoryService;
import com.javachap.utils.HibernateUtils;

/**
 * @author Varma
 *
 */
public class CategoryServiceImpl extends ServiceImpl implements CategoryService {

	private static final long serialVersionUID = 380026904541710183L;
	
	private String ALL_CATEGORIES_QUERY = "from Category category";
	
	private String CATEGORY_BY_NAME_QUERY = 
		"from Category category where category.name = :CategoryName";
	
	/**
	 * Singleton Instance of CategoryServiceImpl
	 */
	private static CategoryServiceImpl categoryServiceImpl = new CategoryServiceImpl();
	
	/**
	 * Creates Instance of {@link CategoryServiceImpl}
	 */
	private CategoryServiceImpl(){		
	}
	
	/***
	 * Gets Instance of CategoryService
	 * @return CategoryService Implementation
	 */
	public static CategoryService getInstance(){	
		return categoryServiceImpl;
	}	

	/* (non-Javadoc)
	 * @see com.javachap.service.CategoryService#getAllCategories()
	 */
	@SuppressWarnings("unchecked")
	public List<Category> getAllCategories() {
		List<Category> categories = null; 
		try {
			Session session = HibernateUtils.currentSession();
			Query query = session.createQuery(ALL_CATEGORIES_QUERY);
			categories = (List<Category>) query.list();
			HibernateUtils.closeSession();
		} catch (Exception e) {
			throw new ServiceException(e);
		}
		return categories;	
	}

	/* (non-Javadoc)
	 * @see com.javachap.service.CategoryService#getCategory(java.lang.Long)
	 */
	public Category getCategory(Long categoryId) {
		Category category = null;
		try {
			Session session = HibernateUtils.currentSession();
			category = (Category)session.get(Category.class, categoryId);
			HibernateUtils.closeSession();
		} catch (Exception e) {
			throw new ServiceException(e);
		}
		return category;
	}

	/* (non-Javadoc)
	 * @see com.javachap.service.CategoryService#getCategory(java.lang.String)
	 */
	public Category getCategory(String categoryName) {
		Category category = null;
		try {
			Session session = HibernateUtils.currentSession();
			Query query = session.createQuery(CATEGORY_BY_NAME_QUERY);
			query.setString("CategoryName", categoryName);
			@SuppressWarnings("unchecked")
			List<Category> list = (List<Category>) query.list();
			if (list.size() == 1) {
				category = (Category) list.get(0);
			}
			HibernateUtils.closeSession();
		} catch (Exception e) {
			throw new ServiceException(e);
		}
		return category;		
	}

	/* (non-Javadoc)
	 * @see com.javachap.service.CategoryService#save(com.javachap.domain.Category)
	 */
	public Category save(Category category) {
		Session session = HibernateUtils.currentSession();
		Transaction tx = null;
		boolean rollback = true;
		try {
		     tx = session.beginTransaction();
		     session.save(category);
		     tx.commit();
		     rollback = false;
		 }
		 catch (Exception e) {
		     throw new ServiceException(e);
		 }
		 finally {
			 if( rollback && tx != null){ 
		    	 tx.rollback();
			 }			 
			 HibernateUtils.closeSession();
		 }
		return category;		
	}
}