JavaWeb项目开发案例精粹-第6章报价管理系统-03Dao层

1.

 package com.sanqing.dao;

 import java.io.Serializable;
 import java.util.LinkedHashMap;

 import com.sanqing.util.QueryResult;

 public interface DAO<T> {
     public long getCount();//获得记录总数
     public void clear();//清除一级缓存的数据
     public void save(Object entity);//保存记录
     public void update(Object entity);//更新记录
     public void delete(Serializable ... entityids);//删除记录
     public T find(Serializable entityId);//通过主键获得记录
     public QueryResult<T> getScrollData(int firstindex, int maxresult, String wherejpql,
                     Object[] queryParams,LinkedHashMap<String, String> orderby);//获得分页记录
     public QueryResult<T> getScrollData(int firstindex, int maxresult,
                                         String wherejpql, Object[] queryParams);//获得分页记录
     public QueryResult<T> getScrollData(int firstindex, int maxresult,
                                         LinkedHashMap<String, String> orderby);//获得分页记录
     public QueryResult<T> getScrollData(int firstindex, int maxresult);        //获得分页记录
     public QueryResult<T> getScrollData();//获得分页记录
 }

2.

 package com.sanqing.dao;

 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
 import java.io.Serializable;
 import java.lang.reflect.Method;
 import java.util.LinkedHashMap;

 import javax.persistence.EmbeddedId;
 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;

 import com.sanqing.util.GenericsUtils;
 import com.sanqing.util.QueryResult;

 @SuppressWarnings("unchecked")
 @Transactional
 public abstract class DaoSupport<T> implements DAO<T>{
     protected Class<T> entityClass = GenericsUtils.getSuperClassGenricType(this.getClass());//获得该类的父类的泛型参数的实际类型
     @PersistenceContext protected EntityManager em;
     public void clear(){//清除一级缓存的数据
         em.clear();
     }
     public void delete(Serializable ... entityids) {//删除记录
         for(Object id : entityids){
             em.remove(em.getReference(this.entityClass, id));
         }
     }
     @Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)
     public T find(Serializable entityId) {//通过主键获得记录
         if(entityId==null) throw new RuntimeException(this.entityClass.getName()+ ":传入的实体id不能为空");
         return em.find(this.entityClass, entityId);
     }
     public void save(Object entity) {//保存记录
         em.persist(entity);
     }
     @Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)
     public long getCount() {    //获得记录总数
         return (Long)em.createQuery("select count("+ getCountField(this.entityClass) +") from "+ getEntityName(this.entityClass)+ " o").getSingleResult();
     }

     protected static <E> String getCountField(Class<E> clazz){
         String out = "o";
         try {
             PropertyDescriptor[] propertyDescriptors = Introspector.getBeanInfo(clazz).getPropertyDescriptors();
             for(PropertyDescriptor propertydesc : propertyDescriptors){
                 Method method = propertydesc.getReadMethod();
                 if(method!=null && method.isAnnotationPresent(EmbeddedId.class)){
                     PropertyDescriptor[] ps = Introspector.getBeanInfo(propertydesc.getPropertyType()).getPropertyDescriptors();
                     out = "o."+ propertydesc.getName()+ "." + (!ps[1].getName().equals("class")? ps[1].getName(): ps[0].getName());
                     break;
                 }
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
         return out;
     }

     protected static 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]);
             }
         }
     }
     protected static String buildOrderby(LinkedHashMap<String, String> orderby){//组装order by语句
         StringBuffer orderbyql = new StringBuffer("");
         if(orderby!=null && orderby.size()>0){
             orderbyql.append(" order by ");
             for(String key : orderby.keySet()){
                 orderbyql.append("o.").append(key).append(" ").append(orderby.get(key)).append(",");
             }
             orderbyql.deleteCharAt(orderbyql.length()-1);
         }
         return orderbyql.toString();
     }
     protected static <E> String getEntityName(Class<E> clazz){//获取实体的名称
         String entityname = clazz.getSimpleName();
         Entity entity = clazz.getAnnotation(Entity.class);
         if(entity.name()!=null && !"".equals(entity.name())){
             entityname = entity.name();
         }
         return entityname;
     }

     public void update(Object entity) {//更新记录
         em.merge(entity);
     }
     @Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)
     public QueryResult<T> getScrollData(int firstindex,
                 int maxresult, LinkedHashMap<String, String> orderby) {//获得分页记录
         return getScrollData(firstindex,maxresult,null,null,orderby);
     }
     @Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)
     public QueryResult<T> getScrollData(int firstindex,
             int maxresult, String wherejpql, Object[] queryParams) {//获得分页记录
         return getScrollData(firstindex,maxresult,wherejpql,queryParams,null);
     }
     @Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)
     public QueryResult<T> getScrollData(int firstindex, int maxresult) {//获得分页记录
         return getScrollData(firstindex,maxresult,null,null,null);
     }
     @Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)
     public QueryResult<T> getScrollData() {
         return getScrollData(-1, -1);
     }
     @Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)
     public QueryResult<T> getScrollData(int firstindex, int maxresult, String wherejpql,
             Object[] queryParams,LinkedHashMap<String, String> orderby) {//获得分页记录
         QueryResult qr = new QueryResult<T>();//查询记录结果
         String entityname = getEntityName(this.entityClass);//获得实体名称
         Query query = em.createQuery("select o from "+
                 entityname+ " o "+(wherejpql==null
                 || "".equals(wherejpql.trim())? "":
                 "where "+ wherejpql)+ buildOrderby(orderby));//执行查询
         setQueryParams(query, queryParams);//设置查询参数
         if(firstindex!=-1 && maxresult!=-1) //两个参数都不是-1的时候才分页
             query.setFirstResult(firstindex).
             setMaxResults(maxresult);//设置查询记录的起始位置和查询最大数
         qr.setResultlist(query.getResultList());//设置查询的记录
         query = em.createQuery("select count(" +
                 getCountField(this.entityClass)+ ") " +
                 "from "+ entityname+ " o "+(wherejpql==null ||
                 "".equals(wherejpql.trim())? "": "where "+ wherejpql));
         setQueryParams(query, queryParams);//设置查询参数
         qr.setTotalrecord((Long)query.getSingleResult());//设置查询记录总数
         return qr;//返回查询记录结果
     }

 }