BaseDAO

package me.irix.dao;

import	java.lang.reflect.*;
import java.util.List;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.MarkerManager;
import org.hibernate.LockOptions;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.criterion.Example;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

@Repository
public class BaseDAO<T> {
	private Class<T> clazz;
	private SessionFactory sessionFactory;
	private Logger logger = LogManager.getLogger(BaseDAO.class);
	private static final Marker DAO_MARKER = MarkerManager.getMarker("DAO");
	
//	public Class<T> getClazz() {
//		return clazz;
//	}
//	
//	@Autowired
//	public void setClazz(Class<T> clazz) {
//		this.clazz = clazz;
//	}

	@SuppressWarnings("unchecked")
	public BaseDAO() {
		super();
		clazz = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];		
	}
	
//	@Autowired
//    public BaseDAO(Class<T> entityClass){
//        this.clazz = entityClass;
//    }

	public SessionFactory getSessionFactory() {
		return sessionFactory;
	}

	@Autowired
	public void setSessionFactory(SessionFactory sessionFactory) {
		this.sessionFactory = sessionFactory;
	}

	public Session getSession() {
		return sessionFactory.getCurrentSession();
	}
	
	public void save(T instance){
//		logger.debug(DAO_MARKER,"Saving instance");
		getSession().save(instance);
	}
	
	public void delete(T instance){
		getSession().delete(instance);
	}
	
	@SuppressWarnings("unchecked")
	public T findById(java.lang.Integer id) {
		logger.debug(DAO_MARKER,"getting " + clazz + " instance with id: " + id);
		try {
			T instance = (T) getSession().get(clazz,id);
			return instance;
		} catch (RuntimeException re) {
			logger.error("get " + clazz + " failed", re);
			throw re;
		}
	}

	@SuppressWarnings("unchecked")
	public List<T> findByExample(T instance) {
		logger.debug(DAO_MARKER,"finding " + clazz + " instance by example");
		try {
			List<T> results = getSession()
					.createCriteria(clazz)
					.add(Example.create(instance)).list();
			logger.debug(DAO_MARKER,"find by example successful, result size: "
					+ results.size());
			return results;
		} catch (RuntimeException re) {
			logger.error("find " + clazz + " by example failed", re);
			throw re;
		}
	}

	@SuppressWarnings("unchecked")
	public List<T> findByProperty(String propertyName, Object value) {
		logger.debug(DAO_MARKER,"finding " + clazz + "instance with property: "
				+ propertyName + ", value: " + value);
		try {
			String queryString = "from " + clazz + " as model where model."
					+ propertyName + "= ?";
			Query queryObject = getSession().createQuery(queryString);
			queryObject.setParameter(0, value);
			
			return queryObject.list();
		} catch (RuntimeException re) {
			logger.error("find " + clazz + " by property name failed", re);
			throw re;
		}
	}

	@SuppressWarnings("unchecked")
	public List<T> findAll() {
		logger.debug(DAO_MARKER,"finding all " + clazz + " instances");
		try {
			String queryString = "from "+ clazz;
			Query queryObject = getSession().createQuery(queryString);
			return (List<T>)queryObject.list();
		} catch (RuntimeException re) {
			logger.error("find all failed", re);
			throw re;
		}
	}

	@SuppressWarnings("unchecked")
	public List<T> findAllBeginAt(int left,int len) {
		logger.debug(DAO_MARKER,"finding " + clazz + " between " + left
				+ " and " + len);
		try {
			String queryString = "from "+ clazz;
			Query queryObject = getSession().createQuery(queryString);
			queryObject.setFirstResult(left);
			queryObject.setMaxResults(len);

			return (List<T>)queryObject.list();
		} catch (RuntimeException re) {
			logger.error("find all failed", re);
			throw re;
		}
	}
	
	@SuppressWarnings("unchecked")
	public T merge(T detachedInstance) {
		logger.debug(DAO_MARKER,"merging " + clazz + " instance");
		try {
			T result = (T) getSession().merge(detachedInstance);
			logger.debug(DAO_MARKER,"merge successful");
			return result;
		} catch (RuntimeException re) {
			logger.error("merge failed", re);
			throw re;
		}
	}

	public void attachDirty(T instance) {
		logger.debug(DAO_MARKER,"attaching dirty " + clazz + " instance");
		try {
			getSession().saveOrUpdate(instance);
			logger.debug(DAO_MARKER,"attach successful");
		} catch (RuntimeException re) {
			logger.error("attach failed", re);
			throw re;
		}
	}

	public void attachClean(T instance) {
		logger.debug(DAO_MARKER,"attaching clean " + clazz + " instance");
		try {
			getSession().buildLockRequest(LockOptions.NONE).lock(instance);
			logger.debug(DAO_MARKER,"attach successful");
		} catch (RuntimeException re) {
			logger.error("attach failed", re);
			throw re;
		}
	}	
}