DAO层重构

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



转发至微博
 



转发至微博