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一个通用的数据访问层实现类

2024-07-07 07:30:45   217人阅读

   在java商城开发中以及人事系统开发中我们知道会涉及到很多的数据表，如果每一个数据库都按照我们开发人员所定义的那样一个表，一个实现类，然后是一个数据访问层接口，数据访问层实现类，业务逻辑层接口，业务逻辑层实现类...这样写下去，代码量无疑是很大的。

下面我们就介绍一个基本的数据访问层实现类，至于接口的定义，我想只要明白实现类，接口的定义应该很简单。

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package cn.com.bochy.crm.dao.impl;
 
import java.io.Serializable;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
 
import javax.annotation.Resource;
 
import org.apache.commons.lang.StringUtils;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.springframework.orm.hibernate3.HibernateCallback;
import org.springframework.orm.hibernate3.HibernateTemplate;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
 
 
 
 
 
 
import cn.com.bochy.crm.dao.BaseDao;
import cn.com.bochy.crm.util.QueryResult;
@SuppressWarnings("rawtypes")
@Transactional(readOnly=true)
@Repository(BaseDao.SERVER_NAME)
public class BaseDaoImpl implements BaseDao {
 
    /*
     * 注入sessionfactory
     * save(Object entity)：保存实体
     * update(Object entity)：修改实体方法
     *  queryById(Class entity, Serializable id):根据id查询实体
     *
     * (non-Javadoc)
     * @see cn.com.bochy.crm.dao.BaseDao#save(java.lang.Object)
     */
     
     
    @Resource(name="hibernateTemplate")
    private HibernateTemplate hibernateTemplate;
     
    @Override
    public Object queryById(Class entity, Serializable id) {
        // TODO Auto-generated method stub
        return hibernateTemplate.get(entity, id);
    }
 
     
    @Override
    @Transactional(isolation=Isolation.DEFAULT,propagation=Propagation.REQUIRED,readOnly=false)
    public void save(Object entity) {
        // TODO Auto-generated method stub
        hibernateTemplate.save(entity);
    }
 
    @Override
    @Transactional(isolation=Isolation.DEFAULT,propagation=Propagation.REQUIRED,readOnly=false)
    public void update(Object entity) {
        // TODO Auto-generated method stub
        hibernateTemplate.update(entity);
    }
     
     
    //删除数据（实体）
 
    @Override
    @Transactional(isolation=Isolation.DEFAULT,propagation=Propagation.REQUIRED,readOnly=false)
    public void delete(Class entity, Serializable... id) {
        // TODO Auto-generated method stub
        //判断id存在
        if(id.length>0&&id!=null){
            //通过for循环来判断id的实体是否存在,存在删除，不存在抛出异常
            for(Serializable ids:id){
           Object entityclass=hibernateTemplate.load(entity, ids);
           if(entityclass==null){
              throw new RuntimeException("实体不存在");  
           }
           hibernateTemplate.delete(entityclass);
           }
        }
    }
 
     
    @Override
    /*
     * 无分页的查询
     * queryListWithNoPage(Class entityClass,String wherehql,Object[] params)
     * String hql="select s from sysusergroup s where 1=1 and s.name like ?"
     * 拼出上面的hql语句需要获得类名，和参数
     * 通过java反射机制获得类名
     */
    public List queryListWithNoPage(Class entityClass, String wherehql,
             final Object[] params,LinkedHashMap<String, String> orderby) {
        // TODO Auto-generated method stub
         
        //通过java反射机制获得类名
        String entityName=entityClass.getSimpleName();
        String hql="select s from "+entityName+" s where 1=1";
         if(StringUtils.isNotBlank(wherehql)){//判断wherehql的返回值是不是为空
             hql=hql+wherehql;
         }
          
         //处理map类型的orderby
          String order=getOrderBy(orderby);
         final String shql=hql+order;
         System.out.println(shql);
         List list=(List)hibernateTemplate.execute(
                 //拟名内部类，在拟名内部类中所有的参数为最终参数
                 new HibernateCallback() {
            @Override
            public Object doInHibernate(Session session) throws HibernateException,
                    SQLException {
                // TODO Auto-generated method stub
                 
                Query query=session.createQuery(shql);
                 
                setQuery(query,params);
                 
                return query.list();
            }
 
        });
          
        return list;
    }
 
     
     
 
     
 
    //放置参数的方法
    protected void setQuery(Query query, Object[] params) {
        // TODO Auto-generated method stub
        if(params!=null&&params.length>0){
            for(int i=0;i<params.length;i++){
                query.setParameter(i, params[i]);
            }
        }
    }
     
    protected String getOrderBy(LinkedHashMap<String, String> orderby) {
        // TODO Auto-generated method stub
         StringBuffer sf=new StringBuffer(" order by ");
         
        if(orderby!=null&&!orderby.isEmpty()){
            Iterator<String> items=orderby.keySet().iterator();
            if(items.hasNext()){
                String key=items.next();
                String val=orderby.get(key);
                sf.append(key);
                sf.append(" "+val);
                 
            }
        }
        String order=sf.toString();
        System.out.println("排序："+order);
        return order;
    }
 
 
    @Override
    public QueryResult PageList(Class entityClass, String wherehql,
            Object[] param, LinkedHashMap<String, String> orderby) {
        // TODO Auto-generated method stub
         
        //利用类反射机制获取类名
        String entityName=entityClass.getSimpleName();
        String hql="select s from "+entityName+" s where 1=1";
        String chql="select count(*) from "+entityName+"s where 1=1";
        if(StringUtils.isNotBlank(wherehql)){
            hql=hql+wherehql;
        }
         
        String order=getOrderBy(orderby);
        final String shql=hql+order;
         
         
        return null;
    }
 
     
     
 
}

　　


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