struts2_spring_jpa

package cn.lvpeng.base; import java.util.LinkedHashMap; import java.util.List; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.Query; import org.springframework.stereotype.Component; import cn.lvpeng.service.QueryResult; @Component public class BaseDaoImpl<T> implements BaseDao<T> { //@Resource可以理解为资源->数据源->也就是数据连接，基本上就是告诉程序数据库在哪里 //@PersistenceContext 注入的是实体管理器，执行持久化操作的，需要配置文件persistence.xml。 @PersistenceContext protected EntityManager em; @Override public void delete(T entity) { em.remove(em.merge(entity)); } @Override public void save(T entity) { em.persist(entity); } @Override public void update(T entity) { em.merge(entity); } @Override public T find(Class<T> clazz, Integer id) { return em.find(clazz, id); } /** * * 总记录 * * */ @Override public QueryResult<T> getScrollData(Class<T> clazz){ return getScrollData(clazz,-1,-1,null,null,null); } /** * * 记录分页 * * */ @Override public QueryResult<T> getScrollData(Class<T> clazz,int startIndex,int maxSize){ return getScrollData(clazz,startIndex,maxSize,null,null,null); } /** * * 记录分页，排序 * * */ @Override public QueryResult<T> getScrollData(Class<T> clazz,int startIndex,int maxSize,LinkedHashMap<String,String> orderby){ return getScrollData(clazz,startIndex,maxSize,null,null,orderby); } /** * * 记录分页，条件查询，排序 * * */ @SuppressWarnings("unchecked") @Override public QueryResult<T> getScrollData(Class<T> clazz, int startIndex, int maxSize,String whereJPQL,Object[] params,LinkedHashMap<String, String> orderby) { String orderbyString=getOrderby(orderby);//设置排序方式 String where=(whereJPQL!=null&&!"".equals(whereJPQL.trim()))?"where "+whereJPQL:""; String JPQL="from "+clazz.getName()+" o "+where+orderbyString; List<T> list=null; Query query1=em.createQuery(JPQL); setParams(query1,params);//设置参数 if(startIndex!=-1&&maxSize!=-1){ query1.setFirstResult(startIndex); query1.setMaxResults(maxSize); } list=query1.getResultList(); Query query2=em.createQuery("select count(*) from "+clazz.getName()+" o "+where); setParams(query2, params); long totalRecord=(Long)query2.getSingleResult(); QueryResult<T> result=new QueryResult<T>(); result.setResult(list); result.setTotalRecord(totalRecord); return result; } /* * * 设置排序条件 * * */ private String getOrderby(LinkedHashMap<String, String> orderby) { StringBuilder str=new StringBuilder(); String orderbyString=""; if(orderby!=null&&orderby.size()>0){ str.append(" order by o."); for(String key:orderby.keySet()){ str.append(key).append(" ").append(orderby.get(key)).append(",o."); } orderbyString=str.substring(0, str.length()-3); } return orderbyString; } /* * * 设置查询条件参数。 * * */ private void setParams(Query query, Object[] params) { if(params!=null&&params.length!=0){ for(int i=0;i<params.length;i++){ query.setParameter(i+1, params[i]); } } } }