基于maven3开发babasport源码(更新到38讲)

package com.itcast.service.base; import com.itcast.bean.QueryResult; import java.util.LinkedHashMap; import javax.persistence.Entity; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.Query; import org.springframework.transaction.annotation.Propagation; import org.springframework.transaction.annotation.Transactional; /** * * @author kang.cunhua */ @Transactional // 后面的方法都会具有默认的事务行为 public abstract class DaoSupport implements DAO { @PersistenceContext protected EntityManager em; // 允许子类访问，不用再在子类中注入 @Override public void save(Object entity) { em.persist(entity); } @Override public void update(Object entity) { em.merge(entity); } @Override public <T> void delete(Class<T> entityClass, Object entityid) { delete(entityClass, new Object[]{entityid}); } @Override public <T> void delete(Class<T> entityClass, Object[] entityids) { for (Object id : entityids) { em.remove(em.getReference(entityClass, id)); } } @Override @Transactional(readOnly = true, propagation = Propagation.NOT_SUPPORTED) public <T> T find(Class<T> entityClass, Object entityId) { return em.find(entityClass, entityId); } @Override @Transactional(readOnly = true, propagation = Propagation.NOT_SUPPORTED) public <T> QueryResult<T> getScrollData(Class<T> entityClass, int firstindex, int maxresult, String wherejpql, Object[] queryParams, LinkedHashMap<String, String> orderby) { QueryResult qr = new QueryResult<T>(); String entityname = getEntityName(entityClass); Query query = em.createQuery("select o from " + entityname + " o " + (wherejpql == null ? "" : "where " + wherejpql) + buildOrderby(orderby)); setQueryParams(query, queryParams); if (firstindex != -1 && maxresult != -1) { query.setFirstResult(firstindex); query.setMaxResults(maxresult); //这两句也可以简写为：query.setFirstResult(firstindex).setMaxResults(maxresult); } qr.setResultlist(query.getResultList()); query = em.createQuery("select count(o) from " + entityname + " o " + (wherejpql == null ? "" : "where " + wherejpql)); setQueryParams(query, queryParams); qr.setTotalrecord((Long) query.getSingleResult()); return qr; } @Override @Transactional(readOnly = true, propagation = Propagation.NOT_SUPPORTED) public <T> QueryResult<T> getScrollData(Class<T> entityClass, int firstindex, int maxresult, LinkedHashMap<String, String> orderby) { return getScrollData(entityClass, firstindex, maxresult, null, null, orderby); } @Override @Transactional(readOnly = true, propagation = Propagation.NOT_SUPPORTED) public <T> QueryResult<T> getScrollData(Class<T> entityClass, int firstindex, int maxresult, String wherejpql, Object[] queryParams) { return getScrollData(entityClass, firstindex, maxresult, wherejpql, queryParams, null); } @Override @Transactional(readOnly = true, propagation = Propagation.NOT_SUPPORTED) public <T> QueryResult<T> getScrollData(Class<T> entityClass, int firstindex, int maxresult) { return getScrollData(entityClass, firstindex, maxresult, null, null, null); } @Override @Transactional(readOnly = true, propagation = Propagation.NOT_SUPPORTED) public <T> QueryResult<T> getScrollData(Class<T> entityClass) { return getScrollData(entityClass, -1, -1); } protected void setQueryParams(Query query, Object[] queryParams) { if (queryParams != null && queryParams.length > 0) { for (int i = 0; i < queryParams.length; i++) { query.setParameter(i + 1, queryParams[i]); } } } /** * 组装order by 语句 * @param orderby * @return */ protected String buildOrderby(LinkedHashMap<String, String> orderby) { StringBuilder orderbyql = new StringBuilder(); if (orderby != null && orderby.size() > 0) { orderbyql.append(" order by "); // order by o.key desc,o.key2 asc for (String key : orderby.keySet()) { orderbyql.append("o.").append(key).append(" ").append(orderby.get(key)).append(","); } orderbyql.deleteCharAt(orderbyql.length() - 1); } return orderbyql.toString(); } /** * 利用反射技术得到要传递到分页方法中的实体类的名字，简单名字还是自定义名字 * @param <T> * @param entityClass * @return */ protected <T> String getEntityName(Class<T> entityClass) { String entityname = entityClass.getSimpleName(); Entity entity = entityClass.getAnnotation(Entity.class); if (entity.name() != null && !"".equals(entity.name())) { entityname = entity.name(); } return entityname; } }