我用的是Spring+Hibernate+Struts框架：
这是我的DAO的核心代码
import org.springframework.orm.hibernate.support.HibernateDaoSupport;
// 用Spring支持的Hibernate方法，使Hibernate对数据库的操作继续瘦身
public List getOfficeBySearchCriteria(final String hsql,final int pageNo,final int page_size) throws DataAccessException // hsql 是如："select office1 from Office as office1 order by office1.officename"；pageNo 是第几页；page_size是每页记录数
{
String sql;
int total_count=0;
List offices=new ArrayList();
//offices= getHibernateTemplate().find("from Office office1 where office1.officename like ?", "%"+officeName+"%");
offices= getHibernateTemplate().find(hsql); //为了得到总记录数
total_count=offices.size();
crossPageInfo= crossPageBean.getCrossPageInfo(total_count,pageNo,page_size);
sql=hsql+ " limit " + (pageNo-1)*page_size + "," +page_size;
offices= getHibernateTemplate().find(sql); //为了得到页记录信息 System.out.println("The list offices size: "+offices.size());
return offices;
}
//其中crossPageBean.getCrossPageInfo只是得到页面的如：总页数、供多少页的信息等一般的翻页信息；
我在Action中是这样调用的：
public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception
{
CrossPageInfo crossPageInfo=new CrossPageInfo();
String hsql="select office1 from Office office1 order by office1.officename";
String pageNo=request.getParameter("pageNo");
int pageNoi=1;
if(pageNo==null)
pageNo="1";
pageNoi=Integer.parseInt(pageNo);
int pageSize=5;
//List offices=getOfficeService().getAllOffice();
List offices=getOfficeService().getOfficeBySearchCriteria(hsql,pageNoi,pageSize);
crossPageInfo=getOfficeService().getCrossPageInfo();
System.out.println("The CorssPgaeInfo :"+crossPageInfo.getPageNo());
System.out.println(crossPageInfo.getPageSize());
request.setAttribute("offices",offices);
request.setAttribute("pageInfo",crossPageInfo);
return mapping.findForward("success");
//throw new UnsupportedOperationException("Generated method 'execute(...)' not implemented.");
}
//其中getOfficeService()只是提供接口服务的方法。
我的表现页面是这样的：
<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>
<%@ taglib uri="/WEB-INF/struts-template.tld" prefix="template" %>
<%@ page import="com.uplus.util.CrossPageInfo"%>
<html>
<head>
<title>
mySearchCList
</title>
</head>
<body bgcolor="#ffffff">
<form name="form1" action="officesearch.do" method="post">
<table >
<tr>
<td>OfficeName:<input name="officeName" type="text"></td><td><input type="submit" name="sb" value="Search"></td>
</tr>
</table>
</form>
<br><a href="/jsp/office/officeadd.jsp">Add</a>
<table bgcolor="#DBE9F1" align="center" class="InputFrameMain" style="MARGIN: 0px" cellSpacing="1" cellPadding="0" BGALIGN="CENTER" BGVALIGn="middle" width="100%" VALIGN="middle" >
<tr><td align="center">OfficeName</td><td align="center">OfficePhone</td></tr>
<logic:iterate id="office" name="offices" >
<tr bgcolor="#ffffff">
<td align="center"><a href="officesee.do?id=<bean:write name='office' property='id'/>" target="_blank"><bean:write name="office" property="officename"/></a></td>
<td align="center"><bean:write name="office" property="officephone"/></td>
<td align="center"><a href="officeedit.do?id=<bean:write name='office' property='id'/>" >Update </a>
<td align="center"><a href="officedel.do?id=<bean:write name='office' property='id'/>" onclick="return confirm('Would You Detele It? ')" >Delete </a>
</tr>
</logic:iterate>
</table>
<%CrossPageInfo cpInfo=(CrossPageInfo)request.getAttribute("pageInfo");%>
<table width="100%" align="center" class="InputFrameMain" style="MARGIN: 0px" cellPadding="0" cellSpacing="0">
<tr ><form action="officelist.do" method="post" onsubmit='return checkform2(this)'>
<td width=70%>Total <font color="blue"><%=cpInfo.getTotalRow()%></font>&items found,Total&<font color="blue"><%=cpInfo.getTotalPage()%></font> Pages,Current No <font color="blue"><%=cpInfo.getPageNo()%> </font>Page.
Go to <input name="pageNo" type="text" size="5" class="input">Page
<input name="sb2" type="submit" class="button" value="Go">
</td></form>
<td width=30% align='left'>
<%if(cpInfo.getPageNo()>1){%>
&<a href="officelist.do?pageNo=1">
<%}%>First</a>
<%if(cpInfo.getPageNo()>1){ %>
&<a href="officelist.do?pageNo=<%=cpInfo.getPageNo()-1%>">
<%}%>Previous</a>
<%if(cpInfo.getPageNo()<cpInfo.getTotalPage()){ %>
&<a href="officelist.do?pageNo=<%=cpInfo.getPageNo()+1%>">
<%}%>Next</a>
<%if(cpInfo.getTotalPage()>cpInfo.getPageNo()){%>
&<a href="officelist.do?pageNo=<%=cpInfo.getTotalPage()%>">
<%}%>Last</a></td>
</tr>
</table>
</body>
</html>
大家可以看一下我的处理过程，其中在DAO里为了得到总计录数执行了一次次数据表查询HSQL；得到数据又执行了一次HSQL，我觉得这样好像有些不太好，大家觉得怎样？大家提出宝贵的意见吧！
sorphi回复:
--------------------------------------------------------------------------------
需要改进:
hsql="select office1 from Office as office1 order by office1.officename"
有两处不好的：
1,实际查出了符合条件的所有po，多么的浪费资源
2,查总记录根本不需要order by这种影响性能的多余的clause
改成"select count(id) from Office where ..."
用query().iterate().next()得到总记录数
另外，分页，hibernate有了相应的包装，不需要你进行这样的sql构造：
sql=hsql+ " limit " + (pageNo-1)*page_size + "," +page_size;
--------------------------------------------------------------------------------
继续:
首先感谢sorphi的建议。
DAO的核心代码改为：
public List getOfficeBySearchCriteria(final String hsql,final int pageNo,final int page_size) throws Exception
{
Session session=getSession();
String sql;
int total_count=0;
int pageNog=1;
total_count=getTotalCount(session,hsql);
//System.out.println("The counts :"+total_count);
List offices=new ArrayList();
crossPageInfo= crossPageBean.getCrossPageInfo(total_count,pageNo,page_size);
pageNog=pageNo;
if(crossPageInfo.getTotalPage()<pageNo)pageNog=crossPageInfo.getTotalPage();
if(pageNo<1)pageNog=1;
// sql=hsql+ " limit " + (pageNog-1)*page_size + "," +page_size;
// offices= getHibernateTemplate().find(sql);
//被屏蔽掉的是原来的处理
//以下是改过的处理方法
Query query=null;
query=session.createQuery(hsql);
int start=(pageNog-1)*page_size;
int rowNum=page_size;
query.setFirstResult(start);
query.setMaxResults(rowNum);
offices = query.list();
return offices;
}
public static int getTotalCount(Session session, String hql) throws Exception
{
Integer amount = new Integer(0);
int sql_from = hql.indexOf(" from");
int sql_orderby=hql.indexOf("order by");//为了改进
String countStr="";
if(sql_orderby>0)
{
countStr="select count(*) "+hql.substring(sql_from,sql_orderby);
}
else
countStr = "select count(*) "+hql.substring(sql_from);
Query query = session.createQuery(countStr);
if(!query.list().isEmpty()){
amount = (Integer) query.list().get(0);
}
else
return 0;
return amount.intValue();
}
