dmitry-osin

package pw.osin.example.data;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.TypedQuery;
import java.util.Collection;
import java.util.List;

public abstract class AbstractJPADataAccess<TKey, TEntity> implements DataAccess<TKey, TEntity> {

dmitry-osin

public void createAll(Collection<TEntity> entities) {
    final EntityTransaction tx = beginTransaction();
    try {
        int i = 0;
        for (final TEntity entity : entities) {
            getEntityManager().persist(entity);
            if (++i % 50 == 0) {
                getEntityManager().flush();
                getEntityManager().clear();
            }

dmitry-osin

public List<TEntity> findAll() {
     final TypedQuery<TEntity> query = getEntityManager().createQuery(String.format("SELECT entity FROM %s entity", 
                                                                                    getType().getSimpleName()), getType());
     return query.getResultList();
}

public List<TEntity> findAll(int size, int offset) {
    final TypedQuery<TEntity> query = getEntityManager().createQuery(String.format("SELECT entity FROM %s entity", 
                                                                                   getType().getSimpleName()), getType());
    query.setFirstResult(offset);

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public TEntity findById(TKey id) {
     return getEntityManager().find(getType(), id);
}

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public TEntity create(TEntity entity) {
        final EntityTransaction tx = beginTransaction();
        try {
            getEntityManager().persist(entity);
            tx.commit();
            return entity;
        } catch (Exception ex) {
            ex.printStackTrace();
            tx.rollback();
            throw new RuntimeException(ex);

dmitry-osin

package pw.osin.example.data;

import pw.osin.example.model.JPAEntity;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.TypedQuery;
import java.util.Collection;
import java.util.List;

dmitry-osin

package pw.osin.example.data;

import pw.osin.example.model.JPAEntity;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.TypedQuery;
import java.util.Collection;
import java.util.List;

dmitry-osin

package pw.osin.example.data;

import pw.osin.example.model.JPAEntity;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;

public abstract class AbstractJPADataAccess<TKey, TEntity> implements DataAccess<TKey, TEntity> {

    protected abstract EntityManager getEntityManager();

dmitry-osin

package pw.osin.example.data;

import javax.persistence.EntityManager;

public abstract class AbstractJPADataAccess<TKey, TEntity> implements DataAccess<TKey, TEntity> {

    protected abstract EntityManager getEntityManager();

    protected abstract Class<TEntity> getType();
    

dmitry-osin

package pw.osin.example.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Tweet {

    @Id