Struts+Hibernate的一个好用分页实例
虽然Hibernate帮助我们完成了分页功能，但若有的数据库不支技分页查询，Hibernate的分页的效率可就不高了，它先查询出一部分然后现在内存当中取出你所要的那一页。
????? Hibernate支持Native SQL（使用SQL Query）也、支持存储过程下面就来说说Hibernate调用存储过程来分页
第一步在数据库创建Ture_Page存储过程
Create?PROCEDURE Ture_Page
??? @PageSize??? int,??????? --每页的行数
??? @PageIndex??? int,??????? --1 代表第一页
??? @Col??????? varchar(250),??? --要显示的字段
??? @Table??????? varchar(200),??? --所用到的表,复条的话就写from与where之间的内容
??? @Where??? varchar(200)='',??? --所用到的条件
??? @OKey??????? varchar(50),??? --排序字段
??? @Order??????? varchar(20)='ASC'?? --排序方式
as
?____declare @cmdstr varchar(2000)
?____declare @cmdstrcount? varchar(2000)
?set no____count on
???????
??????? set @cmdstr='____select top '
??????? set @cmdstr=@cmdstr+convert(nvarchar,@PageSize)
??????? if @Order='DESC' and @PageIndex>1
?set @cmdstr=@cmdstr+' '+@Col+' from '+@Table+' where '+@OKey+'<'
??????? else if @PageIndex=1
?set @cmdstr=@cmdstr+' '+@Col+' from '+@Table+' where '+@OKey+'>='
??????? else
?set @cmdstr=@cmdstr+' '+@Col+' from '+@Table+' where '+@OKey+'>'
??????? if @PageIndex>1
????????? begin
?? if @Order='ASC'
???????????? set @cmdstr=@cmdstr+'(____select max ('+@OKey+') from (____select top '
? else
??????? set @cmdstr=@cmdstr+'(____select min ('+@OKey+') from (____select top '
??????????? set @cmdstr=@cmdstr+convert(nvarchar,(@PageIndex-1)*@PageSize)
????? if @Where<>''
????????????? set @cmdstr=@cmdstr+' '+@OKey+' from '+@Table+'?? where?? '+@Where+'?? order by '+@OKey+' '+@Order+') as t) '
? else
???????????????? set @cmdstr=@cmdstr+' '+@OKey+' from '+@Table+'??? order by '+@OKey+' '+@Order+') as t) '
????????? end
??????? else
????????? set @cmdstr=@cmdstr+' 0 ' --convert(nvarchar,0)
???????? print @cmdstr
??????? if @Where<>''
??????????? set @cmdstr=(@cmdstr+'? and '+@Where+' order by '+@OKey+' '+@Order)
??????? else
??????????? set @cmdstr=(@cmdstr+'? order by '+@OKey+' '+@Order)
???????
?????? print @cmdstr
??????? exec(@cmdstr)
??? set no____count off
GO
SET QUOTED_IDENTIFIER OFF
GO
SET ANSI_NULLS ON
GO
第二部 在相应Hibernate中entity实体相对应的xx.hbm.sml中作如下的配置：
????
<hibernate-mapping>
??? <class name="com.svse.entity.TNew" table="t_new" schema="dbo" catalog="shoa">
??????? <id name="NId" type="java.lang.Integer">
??????????? <column name="n_id" />
??????????? <generator />
??????? </id>
??????? <property name="NTitle" type="java.lang.String">
??????????? <column name="n_title" length="50" />
??????? </property>
??????? <property name="NContent" type="java.lang.String">
??????????? <column name="n_content" />
??????? </property>
??????? <property name="NDate" type="java.util.Date">
??????????? <column name="n_date" length="23" />
??????? </property>
??????? <property name="NFlag" type="java.lang.Integer">
??????????? <column name="n_flag" />
??????? </property>
??? </class>
??? <!-- 存储过程 -->
?? <sql-query name="newsTurnPage" callable="true">
? <return alias="TNew" column="n_id"/>
?? <return-property name="NTitle" column="n_title"/>
?? <return-property name="NContent" column="n_content" />
??? <return-property name="NDate" column="n_date"/>
?? <return-property name="NFlag" column="n_flag" />
? </return>
? {call Ture_Page(?,?,?,?,?,?,?)}
? </sql-query>
</hibernate-mapping>
?
?第三部?查询方法的实现
//分页查询
??? public List turnPage(int size, int currpage) {
????
??List list=new ArrayList();
??try {
???this.beginTran();
???Query query=this.getSession().getNamedQuery("newsTurnPage");
???query.setInteger(0,size);
??????????? query.setInteger(1, currpage);
??????????? query.setString(2, "n_id,n_title,n_content,n_date,n_flag");
??????????? query.setString(3, "t_new");
??????????? query.setString(4,"");
??????????? query.setString(5, "n_id");
??????????? query.setString(6, "desc");
???list = query.list();
??} catch (Exception e) {
???e.printStackTrace();
??}finally{
???this.end();
??}
??return list;
?}
第四步 分页相关设置
public ActionForward getAllNews(ActionMapping mapping, ActionForm form,
???HttpServletRequest request, HttpServletResponse response) {
??//查出所有的新闻
??List list = nd.getAllNews();
??int flag = Integer.parseInt(request.getParameter("flag"));
??//新闻分页
??String action=request.getParameter("action");
??String cp=request.getParameter("curpage");
??int curpage=0;
??//总共有多少也
??int count=list.size();
??//每一页有多少条记录
??int i=10;
??//计算一共也多少页
??int allpage=count%i;
??if(allpage>0)
??{
???allpage=(count/i)+1;
??}
??else
??{
???allpage=count/i;
??}
??//判断传来的当前页
??if(cp==null)
??{
???curpage=1;
??}
??else
??{
???curpage=Integer.parseInt(cp);
??}
??//判断操作
??if(action==null)
??{
???action="first";
??}
??//第一次进来或是首页
??if(action.equalsIgnoreCase("first"))
??{
???curpage=1;
??}
??//前一页
??if(action.equalsIgnoreCase("front"))
??{
???if(curpage<=1)
???{
????curpage=1;
???}
???else
???{
????curpage=curpage-1;
???}
??}
??//后一页
??if(action.equalsIgnoreCase("next"))
??{
???if(curpage>=list.size())
???{
????curpage=curpage;
???}
???else
???{
????curpage=curpage+1;
???}
??}
??//最后一夜
??if(action.equalsIgnoreCase("last"))
??{
???curpage=allpage;
??}
??//获得分页信息
??List list1=nd.turnPage(i, curpage);
??
??request.setAttribute("NewsList", list1);
??request.setAttribute("count", new Integer(count));
??request.setAttribute("curpage", new Integer(curpage));
??request.setAttribute("allpage", new Integer(allpage));
??if (flag == 1) {
???return mapping.findForward("showNews");
??} else {
???return mapping.findForward("showNews2");
??}
??
?}
第五 页面应用
在本类中，调用查询类存储过程时，调用session.getNamedQuery("…")方法来获得User.hbm.xml中配置的查询存储过程。在其余的存储过程调用的测试中，首先通过hibernate的session获得connection，然后调用connection对象的相应方法来实现存储过程的调用。
同样，这样做的话也会带来弊端可移植性差。改库的话也要创建该存储过程
