DAO层重构

来源：互联网发布：mmd制作软件手机编辑：程序博客网时间：2024/05/16 17:27

通用DAO层接口:ICommonDao:

package com.lrq.dao.base;

import java.io.Serializable;
import java.util.Collection;


public interface ICommonDao<T> {
       
    public void persist(T t);
   
    public void delete(Serializable id);
        
    public void update(T t);
    
    public T get(Class<T> clazz,Serializable id);
 
    public Collection<T> listAll();
}

通用Dao实现CommonDaoImpl:

package com.lrq.dao.base.impl;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.util.Collection;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.orm.hibernate3.HibernateTemplate;

import com.lrq.dao.base.ICommonDao;

public abstract class CommonDaoImpl<T> implements ICommonDao<T> {

        private Class clazz;
        @Autowired
  public HibernateTemplate hibernateTemplate;

     public CommonDaoImpl() {
            ParameterizedType type = (ParameterizedType) this.getClass()
                                .getGenericSuperclass();
            clazz = (Class) type.getActualTypeArguments()[0];
   }

       public void persist(T t) {
          if (t != null)
                      hibernateTemplate.persist(t);
       }

       @SuppressWarnings("unchecked")
      public void delete(Serializable id) {
               if (id != null) {
                   Object entity = hibernateTemplate.get(clazz, id);
                   if (entity != null)
                         hibernateTemplate.delete(entity);
           }
   }

       public void update(T t) {
           if (t != null) {
                    hibernateTemplate.update(t);
                }
   }

       @SuppressWarnings("unchecked")
      public T get(Class<T> clazz, Serializable id) {
               return (T) (id == null ? null : hibernateTemplate.get(clazz, id));
  }

       @SuppressWarnings("unchecked")
      public Collection<T> listAll() {
              return hibernateTemplate.find("from  " + clazz.getSimpleName());
            
    }

}

具体的某个实体DAO:

package com.lrq.dao;

import java.util.Collection;

import com.lrq.dao.base.ICommonDao;
import com.lrq.domain.Privilege;

public interface IPrivilegeDao extends ICommonDao<Privilege> {
    
    public Privilege getPrivilegeByName(String nodeName);
       
    public Collection<Privilege> getPrivilegesByIds(String ids);
  
}

对应的Dao实现:

package com.lrq.dao.impl;

import java.util.Collection;
import java.util.List;

import org.springframework.stereotype.Repository;

import com.lrq.dao.IPrivilegeDao;
import com.lrq.dao.base.impl.CommonDaoImpl;
import com.lrq.domain.Privilege;
import com.lrq.util.StringUtils;

import freemarker.template.utility.StringUtil;

@Repository
public class PrivilegeDaoImpl extends CommonDaoImpl<Privilege> implements
              IPrivilegeDao {

 @SuppressWarnings("unchecked")
      public Privilege getPrivilegeByName(String nodeName) {
              // 如果 入的参数都为null,我认为没必要和数据库进行交互,直接返回null;
             if (StringUtils.isEmpty(nodeName))
                  return null;
                List<Privilege> list = hibernateTemplate.find(
                                "from Privilege where name=?", nodeName);
           return list != null && list.size() > 0 ? list.get(0) : null;
 }

       @SuppressWarnings("unchecked")
      public Collection<Privilege> getPrivilegesByIds(String ids) {
         if (!StringUtils.isEmpty(ids)) {
                    StringBuffer sb = new StringBuffer();
                       sb.append("from  Privilege where id in(");
                  sb.append(ids);
                     sb.append(" )");
                    System.out.println(sb.toString());
                  List<Privilege> list = this.hibernateTemplate.find(sb.toString());
                    return list;
                }
           return null;
        }
}

注意:通用的Dao实现是一个抽象类,而且必须这么做;因为他不能有实例对象

0 0