PersistM.java

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/*
 * Project: Server for annotations sharing
 * Author: Ing. Jaroslav Dytrych idytrych@fit.vutbr.cz
 * File: PersistM.java
 * Description: Persistence manager (class for manipulating with database)
 */

/**
 * @file PersistM.java
 *
 * @brief Persistence manager (database manipulator)
 */

package cz.vutbr.fit.knot.annotations.app;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;


/**
 * Persistence manager (class for manipulating with database)
 *
 * @brief Persistence manager (database manipulator)
 * @author idytrych
 */
public class PersistM implements Serializable {

  private EntityManagerFactory entityManagerFactory;

  /**
   * Constructor.
   */
  public PersistM() {
    entityManagerFactory = Persistence.createEntityManagerFactory("AnnotationsPU");
  }

  /**
   * Gets entity manager.
   * 
   * @return entity manager
   */
  public EntityManager getEM() {
    return entityManagerFactory.createEntityManager();
  }

  /**
   * Gets entity from the database
   *
   * @param entityName Name of entity
   * @param id Id of entity
   * @return If entity was found, returns requested entity, else returns null
   */
  public Object getEntityById(String entityName, int id) {
    EntityManager em = getEM();
    try {
      Query q = em.createNamedQuery(entityName + ".findById");
      q.setParameter("id", id);
      List l = q.getResultList();
      if (l.isEmpty()) {
        return null;
      }
      return l.get(0);
    } catch (Exception e) {
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "getEntityById", e);
      }
      return null;
    } finally {
      em.close();
    }
  }

  /**
   * Gets list of entities with given name from the database
   *
   * @param entityName Name of entities
   * @return If succeed, returns list of entities, else returns null
   */
  public List getEntitiesByName(String entityName) {
    EntityManager em = getEM();
    try {
      Query q = em.createNamedQuery(entityName + ".findAll");
      return q.getResultList();
    } catch (Exception e) {
      System.out.print("EXCEPTION "+e.getLocalizedMessage());
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "getEntitiesByName", e);
      }
      return null;
    } finally {
      em.close();
    }
  }

  /**
   * Query database with named query
   *
   * @param queryName Name of query
   * @return If succeed, returns list of results, else returns null
   */
  public List queryDB(String queryName) {
    EntityManager em = getEM();
    try {
      Query q = em.createNamedQuery(queryName);
      q.setHint("javax.persistence.cache.storeMode", "REFRESH");
      return q.getResultList();
    } catch (Exception e) {
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "queryDB:" + queryName, e);
      }
      return null;
    } finally {
      em.close();
    }
  }

  /**
   * Query database with named query with parameters
   *
   * @param queryName Name of query
   * @param params Array of parameters
   * @return If succeed, returns list of results, else returns null
   */
  public List queryDB(String queryName, Object[] params) {
    EntityManager em = getEM();
    try {
      Query q = em.createNamedQuery(queryName);
      q.setHint("javax.persistence.cache.storeMode", "REFRESH");
      for (int p = 0; p < params.length; p = p + 2) {
        q.setParameter((String) params[p], params[p + 1]);
      }
      return q.getResultList();
    } catch (Exception e) {
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "queryDB:" + queryName, e);
      }
      return null;
    } finally {
      em.close();
    }
  }

  /**
   * Persist entity in database
   * 
   * @param entity Entity to be saved
   * @return In case of error returns true, false otherwise
   */
  public boolean persistEntity(Object entity) {
    EntityManager em = getEM();
    try {
      EntityTransaction transaction = em.getTransaction();
      transaction.begin();
      em.persist(entity);
      em.flush();
      transaction.commit();
    } catch (Exception e) {
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        String eString = "";
        if (entity != null) {
          eString = entity.toString();
        }
        System.out.println(e.getMessage());
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "persistEntity: " + eString, e);
      }
      return true;
    } finally {
      em.close();
    }
    return false;
  }
  
  
  /**
   * Persist list of entities in to database
   * 
   * @param entity list of entities to be saved
   * @return In case of error returns true, false otherwise
   */
  public boolean persistEntities(ArrayList<Object> entity) {
    EntityManager em = getEM();
    if(entity != null && !entity.isEmpty()){
      Iterator<Object> objIt = entity.iterator();
      Object ent = null;
      try {
        EntityTransaction transaction = em.getTransaction();
        transaction.begin();
        int counter = 0;
        
        while(objIt.hasNext()){ 
          ent = objIt.next();
          em.persist(ent);
          if ((counter % 10000) == 0) {
            em.getTransaction().commit();
            em.clear();          
            em.getTransaction().begin();
          }
        }
        transaction.commit();
      } catch (Exception e) {
        if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
          String eString = "";
          if (ent != null) {
            eString = ent.toString();
          }
          System.out.println("Crash! " + e.getMessage() + " :: " +eString);
          Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "persistEntity: " + eString, e);
        }
        return true;
      } finally {
        em.close();
      }
    }
    return false;
  }

  /**
   * Saves changes in entity to database
   * 
   * @param entity Entity to be saved
   * @return In case of failure returns null, saved entity otherwise
   */
  public Object saveEntityChanges(Object entity) {
    EntityManager em = getEM();
    try {
      EntityTransaction transaction = em.getTransaction();
      transaction.begin();
      entity = em.merge(entity);
      em.flush();
      transaction.commit();
    } catch (Exception e) {
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        String eString = "";
        if (entity != null) {
          eString = entity.toString();
        }
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "saveEntityChanges: " + eString, e);
      }
      return null;
    } finally {
      em.close();
    }
    return entity;
  }

  /**
   * Removes entity from database
   *
   * @param entity Entity to be removed
   * @return In case of error returns true, false otherwise
   */
  public boolean removeEntity(Object entity) {
    EntityManager em = getEM();
    try {
      EntityTransaction transaction = em.getTransaction();
      transaction.begin();
      entity = em.merge(entity);
      em.remove(entity);
      em.flush();
      transaction.commit();
    } catch (Exception e) {
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        String eString = "";
        if (entity != null) {
          eString = entity.toString();
        }
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "removeEntity: " + eString, e);
      }
      return true;
    } finally {
      em.close();
    }
    return false;
  }
  
  /**
   * Removes all entities from database table
   *
   * @param tableName Name of table
   * @return In case of error returns true, false otherwise
   */
  public boolean deleteTable(String tableName) {
    EntityManager em = getEM();
    EntityTransaction transaction = em.getTransaction();

    try {  
      transaction.begin();
      Query q1 = em.createQuery("DELETE FROM " + tableName);
      q1.executeUpdate();
      transaction.commit();
    }
    catch(Exception e){
      if (Constants.LOG_LEVEL >= Constants.LOG_LEVEL_ALL) {
        Logger.getLogger(PersistM.class.getName()).log(Level.ALL, "Can't delete content of table: " + tableName, e);
      }
      return true;
    } finally {
      em.close();
    }
    return false;
  }
}  // class PersistM