设计模式一点思索

近段要实现一个上传excel文件到服务器,并把excel文件的数据导入到数据库表中的功能。
excel文件有两种格式，对应数据库两张表。我先实现了其中一种excel格式式的上传和导入数据。
上传的功能是一样的，没什么好说的。不同的是两种excel文件格式不一样，对应的数据库表的字段也不一样。
怎么办呢？

开始的时候，我先做了一个excel文件的功能。做另一个很相似了，运用c/p大法就搞定了:)。

代码是这样的.
action中:


CityDayService cds = new CityDayServiceImpl();


ImpExcelData impExcelData = new ImpExcelData(filePath, 0); //这里从excel文件中取出数据




try ...{


List list = impExcelData.getData(); //放进list中.用的是jxl


List<CityDay> sameList = cds.sameList(list);//这里有不同




//boolean isOk = cds.checkExcel(list);




if (sameList.size()>0) ...{


request.setAttribute("sameList", sameList);


request


.setAttribute("echo",


"以下数据有重复，是否覆盖");


return mapping.findForward("upload");




} else ...{




cds.add(list);//这里有不同


}


System.out.print("");




} catch (Exception e) ...{


// TODO Auto-generated catch block


e.printStackTrace();


}



另一种格式的excel文件对应的action是这样的.

/* 导入表 */




ZhbTCityDayForecastService cds = new ZhbTCityDayForecastServiceImpl();/**//////////////////


ImpExcelData impExcelData = new ImpExcelData(filePath, 0);




try ...{


List list = impExcelData.getData();




List<ZhbTCityDayForecast> sameList = cds.sameList(list);/**/////////////////////




if (sameList.size()>0) ...{


request.setAttribute("sameList", sameList);


request


.setAttribute("echo",


"数据有重复，是否覆盖");


return mapping.findForward("upload");




} else ...{






cds.add(list);/**////////////////////////////////


}


System.out.print("");




} catch (Exception e) ...{


// TODO Auto-generated catch block


e.printStackTrace();


}



业务层




public interface CityDayService...{


public List findByCityAndDate(String city,Date date);


public void deleteSame(List excelDataList);


public void add(List excelDatalist);


public List sameList(List excelDatalist);


}

和




public interface ZhbTCityDayForecastService...{


public List findByCityAndDate(String city,Date date);


public void deleteSame(List excelDataList);


public void add(List excelDatalist);


public List sameList(List excelDatalist);


}

业务层实现类




public class CityDayServiceImpl implements CityDayService ...{






public List findByCityAndDate(String city, Date date) ...{


CityDayDAO cdd = new CityDayDAOImpl();


return cdd.findByCityAndDate(city, date);


}






public void add(List excelDatalist) ...{


Session session = HibernateSessionFactory.getSession();


Transaction tran = session.beginTransaction();


List<CityDay> newList = new ArrayList();




for (int i = 1; i < excelDatalist.size(); i++) ...{


HashMap map = (HashMap) excelDatalist.get(i);


String strDate = map.get(1) + "";


Date date;




try ...{


date = new SimpleDateFormat("yyyy-MM-dd").parse(strDate);


CityDayDAO cdd = new CityDayDAOImpl();


CityDay cd = new CityDay();


cd.setDate(date);


cd.setCity(map.get(2) + "");


cd.setPollutionIndeces(new Integer(map.get(3)+""));


cd.setMainPollutant(map.get(4).toString());


cd.setGrade(map.get(5).toString());


cd.setStatus(map.get(6).toString());


cdd.saveOrUpdate(cd);




} catch (ParseException e) ...{


tran.rollback();


e.printStackTrace();


}




}


tran.commit();


}






public void deleteSame(List excelDataList) ...{




CityDayDAO cdd = new CityDayDAOImpl();


boolean result = true;


List<CityDay> list = new ArrayList<CityDay>();




for (int i = 1; i < excelDataList.size(); i++) ...{


HashMap map = (HashMap) excelDataList.get(i);


String city = map.get(2) + "";


String strDate = map.get(1) + "";


Date date;




try ...{


date = new SimpleDateFormat("yyyy-MM-dd").parse(strDate);


List onelist = cdd.findByCityAndDate(city, date);




for(int j=0;j<onelist.size();j++)...{


list.add((CityDay)onelist.get(j));


}




} catch (ParseException e) ...{


// TODO Auto-generated catch block


e.printStackTrace();


}




}




for(int j=0;j<list.size();j++)...{


CityDay cd = (CityDay)list.get(j);


System.out.println("111要删除的数据有: " + "city:"+cd.getCity()+"date:" + cd.getDate());


}


cdd.delete(list);


}






public List<CityDay> sameList(List excelDatalist) ...{


CityDayDAO cdd = new CityDayDAOImpl();


boolean result = true;


List<CityDay> list = new ArrayList<CityDay>();




for (int i = 1; i < excelDatalist.size(); i++) ...{


HashMap map = (HashMap) excelDatalist.get(i);


String city = map.get(2) + "";


String strDate = map.get(1) + "";


Date date;




try ...{


date = new SimpleDateFormat("yyyy-MM-dd").parse(strDate);


List onelist = cdd.findByCityAndDate(city, date);




for(int j=0;j<onelist.size();j++)...{


list.add((CityDay)onelist.get(j));


}




} catch (ParseException e) ...{


// TODO Auto-generated catch block


e.printStackTrace();


}




}




for(int j=0;j<list.size();j++)...{


CityDay cd = (CityDay)list.get(j);


System.out.println("111重复的数据有: " + "city:"+cd.getCity()+"date:" + cd.getDate());


}


return list;


}




}



和




public class ZhbTCityDayForecastServiceImpl implements ZhbTCityDayForecastService ...{






public List findByCityAndDate(String city, Date date) ...{


ZhbTCityDayForecastDAO cdd = new ZhbTCityDayForecastDAOImpl();


return cdd.findByCityAndDate(city, date);


}






public void add(List excelDatalist) ...{


Session session = HibernateSessionFactory.getSession();


Transaction tran = session.beginTransaction();


List<CityDay> newList = new ArrayList();




for (int i = 1; i < excelDatalist.size(); i++) ...{


HashMap map = (HashMap) excelDatalist.get(i);


String strDate = map.get(2)+"-"+map.get(3)+"-"+map.get(4) + "";


Date date;




try ...{


date = new SimpleDateFormat("yyyy-MM-dd").parse(strDate);


ZhbTCityDayForecastDAO cdd = new ZhbTCityDayForecastDAOImpl();


ZhbTCityDayForecast cd = new ZhbTCityDayForecast();


cd.setCity(map.get(1) + "");


cd.setDate(date);


cd.setPollutionMin(new Integer(map.get(5)+""));


cd.setPollutionMax(new Integer(map.get(6)+""));


cd.setMainPollutant(map.get(7)+"");


cd.setGrade(map.get(8).toString());


cd.setStatus(map.get(9).toString());


cdd.saveOrUpdate(cd);




} catch (ParseException e) ...{


tran.rollback();


e.printStackTrace();


}




}


tran.commit();


}








public void deleteSame(List excelDataList) ...{




ZhbTCityDayForecastDAO cdd = new ZhbTCityDayForecastDAOImpl();


boolean result = true;


List<ZhbTCityDayForecast> list = new ArrayList<ZhbTCityDayForecast>();




for (int i = 1; i < excelDataList.size(); i++) ...{


HashMap map = (HashMap) excelDataList.get(i);


String city = map.get(1) + "";


String strDate = map.get(2)+"-"+map.get(3)+"-"+map.get(4) + "";


Date date;




try ...{


date = new SimpleDateFormat("yyyy-MM-dd").parse(strDate);


List<ZhbTCityDayForecast> onelist = cdd.findByCityAndDate(city, date);




for(int j=0;j<onelist.size();j++)...{


list.add((ZhbTCityDayForecast)onelist.get(j));


}




} catch (ParseException e) ...{


// TODO Auto-generated catch block


e.printStackTrace();


}




}


cdd.delete(list);


}






public List<ZhbTCityDayForecast> sameList(List excelDatalist) ...{


// TODO Auto-generated method stub


ZhbTCityDayForecastDAO cdd = new ZhbTCityDayForecastDAOImpl();


List<ZhbTCityDayForecast> list = new ArrayList<ZhbTCityDayForecast>();




for (int i = 1; i < excelDatalist.size(); i++) ...{


HashMap map = (HashMap) excelDatalist.get(i);


String city = map.get(1) + "";


String strDate = map.get(2)+"-"+map.get(3)+"-"+map.get(4) + "";


Date date;




try ...{


date = new SimpleDateFormat("yyyy-MM-dd").parse(strDate);


List onelist = cdd.findByCityAndDate(city, date);




for(int j=0;j<onelist.size();j++)...{


list.add((ZhbTCityDayForecast)onelist.get(j));


}




} catch (ParseException e) ...{


// TODO Auto-generated catch block


e.printStackTrace();


}


}


return list;


}




}





这样做完后,自己感觉很不满意.因为两个相似的功能,写了两遍代码:两个action,service,还有两个页面.很笨.
如果以后需求增加,再写其它的excel格式岂不是很惨.又要用cp大法了.初步的思路是只一个action和一个页面.
经过思索,发现,只有service层的


public void add(List excelDatalist);


public List sameList(List excelDatalist);


public void deleteSame(List excelDataList);

三个方法是不同的.

那么在action中可以根据参数生成不同的service,执行不同的service中的service方法.可以用工厂方法生产出不
同的service.
思路有了,开干.

首先把这三个方法提到一个接口里来.




public interface CommonUploadService ...{


public void add(List excelDatalist);


public List sameList(List excelDatalist);


public void deleteSame(List excelDataList);


}

原为的service就变成这样

实现类不用变.

工厂方法




public class UploadServiceFactory ...{




private static CommonUploadService cus;




private static final String cityDayService = "com.xxx.datacenter.upload.service.CityDayServiceImpl";




private static final String foreCastService = "com.xxx.datacenter.upload.forecast.service.CityDayServiceImpl";






private UploadServiceFactory() ...{


}






public static CommonUploadService getInstance(String type) ...{




try ...{




if ("daily".equals(type)) ...{


Class cls = Class.forName(cityDayService);


cus = (CommonUploadService) cls.newInstance();


}




if ("forecast".equals(type)) ...{


Class cls = Class.forName(foreCastService);


cus = (CommonUploadService) cls.newInstance();


}




} catch (Exception e) ...{


e.printStackTrace();


}


return cus;


}


}





改造后的action




/**//* 导入表 */


// CityDayService cds = new CityDayServiceImpl();//这里有不同 可以用工厂方法，根据参数type不同构造出


String type = request.getParameter("type");


CommonUploadService cds = UploadServiceFactory.getInstance(type);


ImpExcelData impExcelData = new ImpExcelData(filePath, 0);




try ...{


List list = impExcelData.getData();


List<CityDay> sameList = cds.sameList(list);//这里有不同




//boolean isOk = cds.checkExcel(list);




if (sameList.size()>0) ...{


request.setAttribute("sameList", sameList);


request


.setAttribute("echo",


"以下数据有重复，是否覆盖");


return mapping.findForward("upload");




} else ...{




cds.add(list);//这里有不同


}


System.out.print("");




} catch (Exception e) ...{


// TODO Auto-generated catch block


e.printStackTrace();


}



这样一个action就可以搞定了.

如果以为要增加新格式的excel文件,只实现CommonUploadService方法,改造一下工厂类就ok了.

总结:
以后遇到功能类似的需求,可以把接口相同,但实现不同的方法提到共的提口来.然后用工厂方法生成不同的实例.
运用面向对象的多态的性能.就可以简化开发.
设计模式关暂在于实践.光看书本是不行的.有什么不对的地方,请多多指点.