使用Hibernate3实现分页功能
?
http://blog.csdn.net/zhjb1025/archive/2006/04/19/668631.aspx
整理的代码如下：
Page.Java接口
packageorg.domain.scrm4u.helper;importjava.util.List;publicinterfacePage{ booleanisFirstPage(); booleanisLastPage(); booleanhasNextPage(); booleanhASPreviousPage(); intgetLastPageNumber(); List<?>getThisPageElements(); intgetTotalNumberOfElements(); intgetThisPageFirstElementNumber(); intgetThisPageLastElementNumber(); intgetNextPageNumber(); intgetPreviousPageNumber(); intgetPageSize(); intgetPageNumber();}?ListPage.java实现：
packageorg.domain.scrm4u.helper.impl;importjava.util.List;importorg.domain.scrm4u.helper.Page;publicclassListPageimplementsPage{ privateList<?>elements; privateintpageSize; privateintpageNumber; publicListPage(List<?>elements,intpageNumber,intpageSize){ this.elements=elements; this.pageSize=pageSize; this.pageNumber=pageNumber; if(Integer.MAX_VALUE==this.pageNumber)this.pageNumber=(getTotalNumberOfElements()/this.pageSize); } publicbooleanisFirstPage(){ returngetPageNumber()==0; } publicbooleanisLastPage(){ returngetPageNumber()>=getLastPageNumber(); } publicbooleanhasNextPage(){ return((getPageNumber()+1)*getPageSize())<(getTotalNumberOfElements()+1); } publicbooleanhasPreviousPage(){ returngetPageNumber()>0; } publicintgetLastPageNumber(){ doubletotalResults=newInteger(getTotalNumberOfElements()).doubleValue(); returnnewDouble(Math.floor(totalResults/getPageSize())).intValue(); } publicList<?>getThisPageElements(){ finalintstart=getPageNumber()*getPageSize(); returnelements.subList( Math.min(start,getTotalNumberOfElements()+1), Math.min(start+getPageSize(),getTotalNumberOfElements()+1) ); } publicintgetTotalNumberOfElements(){ returnelements.size()-1; } publicintgetThisPageFirstElementNumber(){ returngetPageNumber()*getPageSize()+1; } publicintgetThisPageLastElementNumber(){ intfullPage=getThisPageFirstElementNumber()+getPageSize()-1; returngetTotalNumberOfElements()<fullPage?getTotalNumberOfElements():fullPage; } publicintgetNextPageNumber(){ returngetPageNumber()+1; } publicintgetPreviousPageNumber(){ returngetPageNumber()-1; } publicintgetPageSize(){ returnpageSize; } publicintgetPageNumber(){ returnpageNumber; }}??
?
HibernatePage.Java实现：
packageorg.domain.scrm4u.helper.impl;importjava.util.List;importorg.domain.scrm4u.helper.Page;importorg.hibernate.HibernateException;importorg.hibernate.Query;importorg.hibernate.ScrollMode;importorg.hibernate.ScrollableResults;publicclassHibernatePageimplementsPage{ protectedList<?>elements; protectedintpageSize; protectedintpageNumber; protectedinttotalElements=0; privateScrollableResultsscrollableResults; privateHibernatePage(intpageNumber,intpageSize){ this.pageNumber=pageNumber; this.pageSize=pageSize; } publicbooleanisFirstPage(){ returngetPageNumber()==0; } publicbooleanisLastPage(){ returngetPageNumber()>=getLastPageNumber(); } publicbooleanhasNextPage(){ returnelements.size()>getPageSize(); } publicbooleanhASPreviousPage(){ returngetPageNumber()>0; } publicintgetLastPageNumber(){ doubletotalResults=newInteger(getTotalNumberOfElements()).doubleValue(); returnnewDouble(Math.floor(totalResults/getPageSize())).intValue(); } publicList<?>getThisPageElements(){ returnhasNextPage()?elements.subList(0,getPageSize()):elements; } publicintgetTotalNumberOfElements(){ returntotalElements; } publicintgetThisPageFirstElementNumber(){ returngetPageNumber()*getPageSize()+1; } publicintgetThisPageLastElementNumber(){ intfullPage=getThisPageFirstElementNumber()+getPageSize()-1; returngetTotalNumberOfElements()<fullPage?getTotalNumberOfElements():fullPage; } publicintgetNextPageNumber(){ returngetPageNumber()+1; } publicintgetPreviousPageNumber(){ returngetPageNumber()-1; } publicintgetPageSize(){ returnpageSize; } publicintgetPageNumber(){ returnpageNumber; } publicstaticHibernatePagegetScrollPage(Queryquery,intpageNumber,intpageSize,ScrollModescrollMode){ HibernatePagesp=newHibernatePage(pageNumber,pageSize); try{ sp.scrollableResults=query.scroll(scrollMode); if(scrollMode==ScrollMode.SCROLL_SENSITIVE){ sp.scrollableResults.last(); sp.totalElements=sp.scrollableResults.getRowNumber(); }else{ sp.totalElements=sp.calculateTotalElementsByList(query); } sp.determineElements(query); }catch(HibernateExceptione){ e.printStackTrace(); } returnsp; } privatevoiddetermineElements(Queryquery)throwsHibernateException{ if(Integer.MAX_VALUE==this.pageNumber)this.pageNumber=(getTotalNumberOfElements()/this.pageSize); elements=query.setFirstResult(this.pageNumber*this.pageSize).setMaxResults(this.pageSize+1).list(); } privateintcalculateTotalElementsByList(Queryquery)throwsHibernateException{ returnquery.list().size(); }}?简单分析一下：
ListPage实现需要把查询的结果集全部取出来。
我们着重还是分析一下HibernatePage的实现。
测试代码如下：
importJava.io.IOException;importjava.sql.SQLException;importjava.util.List;importorg.hibernate.Query;importorg.hibernate.ScrollMode;importorg.hibernate.Session;importorg.hibernate.SessionFactory;importorg.hibernate.cfg.AnnotationConfiguration;importorg.hibernate.cfg.Configuration;importorg.domain.scrm4u.helper.Page;importorg.domain.scrm4u.helper.impl.HibernatePage;importorg.domain.scrm4u.entity.TPsn;publicclassBusinessService{ publicstaticvoidmain(String[]args)throwsIOException,SQLException{ Configurationconfig= newAnnotationConfiguration().configure(); SessionFactorysessionFactory=config.buildSessionFactory(); Sessionsession=sessionFactory.openSession(); StringHql="fromTPsn"; Queryquery=session.createQuery(Hql); Pagepage=HibernatePage.getScrollPage(query,0,10,ScrollMode.SCROLL_SENSITIVE); List<?>list=page.getThisPageElements(); for(inti=0;i<list.size();i++){ TPsnpsn=(TPsn)list.get(i); System.out.println(psn.getPsnNo()+"t"+psn.getPsnPnm()+"t"+psn.getPsnBrthDt()); } session.close(); sessionFactory.close(); }}??
测试中发现：
使用ScrollMode.SCROLL_SENSITIVE比ScrollMode.FORWARD_ONLY在性能上要快很多。具体选择要看使用的JDBC驱动是否支撑了，支持scroll的话就可以使用ScrollableResults类来处理结果集了。
当然，我们还可以配合缓存技术让翻页更有效率。
关于缓存请参看http://blog.csdn.net/kunshan_shenbin/archive/2008/09/03/2874992.ASPx。