利用hibernate的DetachedCriteria进行分页
Hibernate3提供了DetachedCriteria，使得我们可以在Web层构造detachedCriteria，然后调用业务层Bean，进行动态条件查询，根据这一功能，我设计了通用的抽象Bean基类和分页类支持，代码来自于QuakeWang的javaeye-core包的相应类，然后又做了很多修改。
分页支持类：
importjava.util.List;
publicclassPaginationSupport{
publicfinalstaticintPAGESIZE=30;//定义一页显示多少行记录
privateintpageSize=PAGESIZE;
privateListitems;//查询的结果集
privateinttotalCount;//一共有多少条适合的记录
privateint[]indexes=newint[0];//查出总记录数后，记录每一页开始的记录号
privateintstartIndex=0;//当前为第几页
/*------------------------------三个构造函数*/
publicPaginationSupport(Listitems,inttotalCount){
setPageSize(PAGESIZE);
setTotalCount(totalCount);
setItems(items);
setStartIndex(0);
}
publicPaginationSupport(Listitems,inttotalCount,intstartIndex){
setPageSize(PAGESIZE);
setTotalCount(totalCount);
setItems(items);
setStartIndex(startIndex);
}
publicPaginationSupport(Listitems,inttotalCount,intpageSize,intstartIndex){
setPageSize(pageSize);
setTotalCount(totalCount);
setItems(items);
setStartIndex(startIndex);
}
publicListgetItems(){
returnitems;
}
publicvoidsetItems(Listitems){
this.items=items;
}
publicintgetPageSize(){
returnpageSize;
}
publicvoidsetPageSize(intpageSize){
this.pageSize=pageSize;
}
publicintgetTotalCount(){
returntotalCount;
}
//设置总的记录数，总页数(count),每一页的开始记录号
publicvoidsetTotalCount(inttotalCount){
if(totalCount>0){
this.totalCount=totalCount;
intcount=totalCount/pageSize;
if(totalCount%pageSize>0)
count++;
indexes=newint[count];
for(inti=0;i<count;i++){
indexes[i]=pageSize*i;
}
}else{
this.totalCount=0;
}
}
publicint[]getIndexes(){
returnindexes;
}
publicvoidsetIndexes(int[]indexes){
this.indexes=indexes;
}
publicintgetStartIndex(){
returnstartIndex;
}
//设置起始页的位置
publicvoidsetStartIndex(intstartIndex){
if(totalCount<=0)
this.startIndex=0;
elseif(startIndex>=totalCount)
this.startIndex=indexes[indexes.length-1];
elseif(startIndex<0)
this.startIndex=0;
else{
this.startIndex=indexes[startIndex/pageSize];
}
}
//下一页
publicintgetNextIndex(){
intnextIndex=getStartIndex()+pageSize;
if(nextIndex>=totalCount)
returngetStartIndex();
else
returnnextIndex;
}
//上一页
publicintgetPreviousIndex(){
intpreviousIndex=getStartIndex()-pageSize;
if(previousIndex<0)
return0;
else
returnpreviousIndex;
}
}
抽象业务类(我们的类要继承这个抽象类，以便使用里面的类进行分类)
importjava.io.Serializable;
importjava.util.List;
importorg.hibernate.Criteria;
importorg.hibernate.HibernateException;
importorg.hibernate.Session;
importorg.hibernate.criterion.DetachedCriteria;
importorg.hibernate.criterion.Projections;
importorg.springframework.orm.hibernate3.HibernateCallback;
importorg.springframework.orm.hibernate3.support.HibernateDaoSupport;
publicabstractclassAbstractManagerextendsHibernateDaoSupport{
privatebooleancacheQueries=false;
privateStringqueryCacheRegion;
publicvoidsetCacheQueries(booleancacheQueries){
this.cacheQueries=cacheQueries;
}
publicvoidsetQueryCacheRegion(StringqueryCacheRegion){
this.queryCacheRegion=queryCacheRegion;
}
//保存
publicvoidsave(finalObjectentity){
getHibernateTemplate().save(entity);
}
publicvoidpersist(finalObjectentity){
getHibernateTemplate().save(entity);
}
//更新
publicvoidupdate(finalObjectentity){
getHibernateTemplate().update(entity);
}
//删除
publicvoiddelete(finalObjectentity){
getHibernateTemplate().delete(entity);
}
//加载
publicObjectload(finalClassentity,finalSerializableid){
returngetHibernateTemplate().load(entity,id);
}
publicObjectget(finalClassentity,finalSerializableid){
returngetHibernateTemplate().get(entity,id);
}
//查询全部
publicListfindAll(finalClassentity){
returngetHibernateTemplate().find("from"+entity.getName());
}
//通过名字查询
publicListfindByNamedQuery(finalStringnamedQuery){
returngetHibernateTemplate().findByNamedQuery(namedQuery);
}
//通过参数动态查询
publicListfindByNamedQuery(finalStringquery,finalObjectparameter){
returngetHibernateTemplate().findByNamedQuery(query,parameter);
}
publicListfindByNamedQuery(finalStringquery,finalObject[]parameters){
returngetHibernateTemplate().findByNamedQuery(query,parameters);
}
publicListfind(finalStringquery){
returngetHibernateTemplate().find(query);
}
publicListfind(finalStringquery,finalObjectparameter){
returngetHibernateTemplate().find(query,parameter);
}
//以下是分页查询
publicPaginationSupportfindPageByCriteria(finalDetachedCriteriadetachedCriteria){
//通过detachedCriteri，一页显示记录数,当前是第几页查询(0)
returnfindPageByCriteria(detachedCriteria,PaginationSupport.PAGESIZE,0);
}
publicPaginationSupportfindPageByCriteria(finalDetachedCriteriadetachedCriteria,finalintstartIndex){
//用户指定当前为第几页
returnfindPageByCriteria(detachedCriteria,PaginationSupport.PAGESIZE,startIndex);
}
publicPaginationSupportfindPageByCriteria(finalDetachedCriteriadetachedCriteria,finalintpageSize,
finalintstartIndex){
//用户同时指定每页显示的记录数，和当前页为第几页
return(PaginationSupport)getHibernateTemplate().execute(newHibernateCallback(){
publicObjectdoInHibernate(Sessionsession)throwsHibernateException{
Criteriacriteria=detachedCriteria.getExecutableCriteria(session);
inttotalCount=((Integer)criteria.setProjection(Projections.rowCount()).uniqueResult()).intValue();
criteria.setProjection(null);
Listitems=criteria.setFirstResult(startIndex).setMaxResults(pageSize).list();
PaginationSupportps=newPaginationSupport(items,totalCount,pageSize,startIndex);
returnps;
}
},true);
}
publicListfindAllByCriteria(finalDetachedCriteriadetachedCriteria){
return(List)getHibernateTemplate().execute(newHibernateCallback(){
publicObjectdoInHibernate(Sessionsession)throwsHibernateException{
Criteriacriteria=detachedCriteria.getExecutableCriteria(session);
returncriteria.list();
}
},true);
}
publicintgetCountByCriteria(finalDetachedCriteriadetachedCriteria){
Integercount=(Integer)getHibernateTemplate().execute(newHibernateCallback(){
publicObjectdoInHibernate(Sessionsession)throwsHibernateException{
Criteriacriteria=detachedCriteria.getExecutableCriteria(session);
returncriteria.setProjection(Projections.rowCount()).uniqueResult();
}
},true);
returncount.intValue();
}
}
用户在web层构造查询条件detachedCriteria，和可选的startIndex，调用业务bean的相应findByCriteria方法，返回一个PaginationSupport的实例ps。
ps.getItems()得到已分页好的结果集
ps.getIndexes()得到分页索引的数组
ps.getTotalCount()得到总结果数
ps.getStartIndex()当前分页索引
ps.getNextIndex()下一页索引
ps.getPreviousIndex()上一页索引