在网上看了几个Structs分页，感觉不是很完善，于是根据自己的经验，写了一个相对高效简洁的分页方法。由于本人水平有限，如果大家有什么更好的想法，欢迎不吝赐教。

一、 开发环境
我的开发环境是：JBuilder x + Weblogic 8.1 + Oracle 9i + Windows 2003 ，如果朋友们的开发环境不一样亦无妨。

二、开发思路
既然讲的是Struts，那自然离不了MVC，分页显示也是如此。
1、 建立数据库和对应的表，本例的表是TCertificate。
2、 建立适当的模型组件，对应你要查询数据库中的表。这部分由DAO数据访问层来实现，如果有的朋友对DAO不熟悉可以查询一下相关资料。本例由CertificateDAO.java来实现。
3 、建立分页所需要的模型组件，由javaBean来充当，并与CertificateDAO实现分离。网上介绍的很多方法，都存在着数据与分页组件藕合的现象，这也是本方法与其它分页方法的主要不同之处。

4、建立控制器组件，这部分由Struts 中的Action来实现。主要负责将实例化CertificateDAO，只取要显示的数据记录，存入ArrayList对象然后返回，并放到request中。而分页部分则根据分页条件，单独进行构造，避免了与DAO混在一起的情况发生。网上其它介绍的一些分页方法中，基本上都是一次性读出所有查询的数据，然后再由分页相关组件进行构造。这样，如果数据量大的话，很容易形成瓶颈。在本例中由于不是一次性地读出查询的所有数据，而只是读出一个页面要显示的数据记录，这就节省了很多不必要的数据传输，提高了效率。本例中为CertificateAction.java。

5、建立视图组件，这部分由jsp来充当，为了不出现java 代码，我们使用Struts提供的标签库，主要负责从request中取出刚刚放入的对象，通过反复调用CertificateAction以及action参数，而实现分页显示。本例中为listcertificate.jsp。
6、 建立并配置struts-config.xml。

三、实例代码
确定好上面的开发思路后，代码的实现就有单可循了。
1、建数据库和相应的表。
2、数据逻辑层的相关代码。
1）、通用的DAO类：CommonDAO.java
这是一个很多DAO都要继承到的通用DAO类，是我根据实践总结出来的，为了减少篇幅，这里只显示和本例相关的代码。

java代码:

package com.xindeco.business ; import java.io.*; import java.sql.*; import java.util.*; import javax.sql.*; import java.lang.IllegalAccessException; import java.lang.reflect.InvocationTargetException; import org.apache.commons.beanutils.BeanUtils; public class DAO {   protected DataSource ds; /**   * 说明:取得当前查询的总记录数   */ public int getRows () {   return this.count; }   public void rsHandler (ResultSet rs, int offset, int limit)   {    try    {     count = 0;     rs.absolute ( -1) ;     count = rs.getRow () ;     if (offset <= 0)     {      rs.beforeFirst () ;     }     else     {      rs.absolute (offset) ;     }    }    catch (Exception e)    {     e.printStackTrace () ;    }   }   public DAO(DataSource ds) {           this.ds = ds;   }   public void setDataSource(DataSource ds) {     this.ds = ds;   }   protected void close(ResultSet rs) {     if (rs != null) {             try {                     rs.close();             } catch (SQLException e) {             }             rs = null;     }   }   protected void close(PreparedStatement pstmt) {     if (pstmt != null) {             try {                     pstmt.close();             } catch (SQLException e) {             }             pstmt = null;     }   }   protected void close(Connection conn) {     if (conn != null) {             try {                     conn.close();             } catch (SQLException e) {                     e.printStackTrace();             }             conn = null;     }   }   protected void rollback(Connection conn) {     if (conn != null) {             try {                     conn.rollback();             } catch (SQLException e) {                     e.printStackTrace();             }             conn = null;     }   } }

这个类主要是通过子类传进来的先进结果集，取得查询的记录总数，并对数据库连接进行简单的管理。
2）、对数据库进行访问：CertificateDAO.java

java代码:

package com.xindeco.business; import java.io.*; import java.sql.*; import java.util.*; import javax.sql.*; import com.xindeco.common.dbconn.DbConn; public class CertificateDAO extends DAO {   public NationDAO(DataSource ds) {     super(ds);   } public List findCertificateList(int offset,int limit) throws SQLException         {         int countRows = 0 ;         ArrayList list = null ;     Connection conn = null;     PreparedStatement pstmt = null; ResultSet rs = null; try         {              conn = ds.getConnection();                 String sql =                                 "SELECT certificateID, certificateCode,certificateName,photoURL,"                                 + "description,graduateID FROM TCertificate " ;       pstmt = conn.prepareStatement(sql);       rs = pstmt.executeQuery();                         /*对游标进行处理，rsHandler 方法在父类DAO中*/                         this.rsHandler(rs,offset,limit);                         if (rs != null && rs.next ())                         {                                 list = new ArrayList () ;                                 do                                 {                                         countRows++ ;                                         list.add (rs2VO (rs)) ;                                 }                                 while ( (countRows++ < limit) && rs.next ()) ;                         }       close(rs);       close(pstmt);           } catch (SQLException e) {       close(rs);       close(pstmt);       rollback(conn);                 e.printStackTrace();                   } finally {             close(conn);     }         return list ;         }         private CertificateVO rs2VO (ResultSet rs)         {                 try                 {                         CertificateVO certificateVO = new CertificateVO () ;                         certificateVO.setCertificateID (rs.getInt ("certificateID")) ;                         certificateVO.setCertificateCode (rs.getString ("certificateCode")) ;                         certificateVO.setCertificateName (rs.getString ("certificateName")) ;                         certificateVO.setPhotoURL (rs.getString ("photoURL")) ;                         certificateVO.setDescription (rs.getString ("description")) ;                         certificateVO.setGraduateID (rs.getInt ("graduateID")) ;                         return certificateVO ;                 }                 catch (Exception ex)                 {                         ex.printStackTrace () ;                         return null ;                 }         } }

findCertificateList(int offset,int limit)是查得所有要显示的数据，并放入ArrayList中。看过网上有些例子，把数据记录放入ArrayList的动作过程直接在while循环体里完成，如果字段多的话，会造成方法过于宠大，又不美观。 这里，数据记录放入ArrayList的动作过程由rs2VO方法完成，就比较整洁了。另外，if (rs != null && rs.next ()) 配合while ( (countRows++ < limit) && rs.next ()) 是为了程序的健壮性考虑的，稍分析一下不难得出结论。

3、建立控制器组件：CertificateAction.java

java代码:

package com.xindeco.presentation; import javax.sql.* ; import java.util.* ; import javax.servlet.http.* ; import javax.servlet.* ; import org.apache.struts.action.* ; import org.apache.struts.util.* ; import com.xindeco.common.Pager; import com.xindeco.business.graduatedata.CertificateDAO ; public class CertificateAction         extends Action {         private static final int PAGE_LENGTH = 5 ; //每页显示5条记录         public ActionForward execute (ActionMapping mapping, ActionForm form,                                                                   HttpServletRequest request,                                                                   HttpServletResponse response)         {                 ActionForward myforward = null ;                 String myaction = mapping.getParameter () ;                 if (isCancelled (request))                 {                         return mapping.findForward ("failure") ;                 }                 if ("".equalsIgnoreCase (myaction))                 {                         myforward = mapping.findForward ("failure") ;                 }                 else if        ("LIST".equalsIgnoreCase (myaction))                 {                         myforward = performList (mapping, form, request, response) ;                 }                 else                 {                         myforward = mapping.findForward ("failure") ;                 }                 return myforward ;         }         private ActionForward performList (ActionMapping mapping,                                                                            ActionForm actionForm,                                                                            HttpServletRequest request,                                                                            HttpServletResponse response)         {                      try                 {         DataSource ds = (DataSource) servlet.getServletContext().getAttribute(Action.DATA_SOURCE_KEY);                 CertificateDAO   certificateDAO  = new CertificateDAO  (ds) ;                         int offset = 0;   //翻页时的起始记录所在游标                         int length = PAGE_LENGTH;                           String pageOffset = request.getParameter("pager.offset");                 if (pageOffset == null || pageOffset.equals("")) {         offset = 0;       } else {         offset = Integer.parseInt(pageOffset);       }                         List certificateList = certificateDAO .findCertificateList (offset,length) ;                         int size = certificateDAO.getRows(); //  取得总记录数                         String url = request.getContextPath()+"/"+mapping.getPath()+".do";                         String pagerHeader = Pager.generate(offset, size, length, url); //分页处理                         request.setAttribute ("pager", pagerHeader) ;                         request.setAttribute ("list", certificateList) ;                 }                 catch (Exception e)                 {                         e.printStackTrace();                         return mapping.findForward ("error") ;                 }                 return mapping.findForward ("success") ;         } }

CertificateAction.java主要是把数据从DAO中取出，并放入一个ArrayList 中，然后通过配置文件再软件View的JSP页。

5、建立视图listcertificate.jsp文件。

java代码:

<%@ page contentType="text/html; charset=GBK" %> <%@ taglib uri="/WEB-INF/struts-template.tld" prefix="template" %> <%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %> <%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %> <%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %> <table bgcolor="#666666" cellpadding="1" cellspacing="0" border="0" width="500"> <tr> <td> <table cellpadding="0" cellspacing="0" border="0" width="500"> <tr> <td bgcolor="#fecc51">&</td> </tr> </table> </td> </tr> <tr> <td> <table cellpadding="0" cellspacing="0" border="0" width="500">   <tr> <td bgcolor="#d6e0ed">     &&<bean:message key="label.list4certificate"/>   </td> </tr> <tr bgcolor="#FFFFFF"> <td width="5%"></td><td width="19%"></td><td width="76%"></td> </tr>     <tr> <td> <table bgcolor="#f2f2f2" width="500" cellspacing="0" border="0">       <tr bgcolor="#bacce1">         <td><b><bean:message key="Certificate.select"/> </b></td>         <td><b><bean:message key="Certificate.certificateID"/> </b></td>         <td><b><bean:message key="Certificate.certificateCode"/></b></td>         <td><b><bean:message key="Certificate.certificateName"/></b></td>         <td><b><bean:message key="Certificate.view"/></b></td>     ?/tr> <bean:write name="pager" property="description"/>   <logic:equal name="pager" property="hasPrevious" value="true">               <a href="/graduatedata/list.do?viewPage=<bean:write name="pager" property="previousPage"/>" class="a02">            Previous         </a>   </logic:equal>   <logic:equal name="pager" property="hasNext" value="true">     ?a href="/graduatedata/list.do?viewPage=<bean:write name="pager" property="nextPage"/>" class="a02">      Next     ?/a>   </logic:equal> <logic:notEmpty name="list" scope="request"> <logic:iterate id="certificate" name="list" type="com.xindeco.business.graduatedata.CertificateVO"scope="request"> <tr bgcolor="#FFFFFF">     ?td><html:text property="name" value="<bean:write name="certificate" property="certificateID" scope="page"/>"/>                 </td>     ?td> <bean:write name="certificate" property="certificateID" scope="page"/></td>     ?td> <bean:write name="certificate" property="certificateCode" scope="page"/></td>     ?td> <bean:write name="certificate" property="certificateName" scope="page"/></td>     ?td> <bean:write name="certificate" property="photoURL" scope="page"/></td> </tr> </logic:iterate> </logic:notEmpty> </table> </td> </tr> </table> </td> </tr> </table>

6、对应的配置文件struts-config.xml。

java代码:

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd"> <struts-config>   <form-beans>     <form-bean name="certificateForm" type="com.xindeco.presentation.graduatedata.CertificateForm" />   </form-beans>   <global-forwards>     <forward name="error" path="/error/error.jsp" />   </global-forwards>   <action-mappings>       <action name="certificateForm" parameter="LIST" path="/graduatedata/list" scope="request" type="com.xindeco.presentation.graduatedata.CertificateAction" validate="true">       <forward name="success" path="/graduatedata/listcertificate.jsp" />     </action>   </action-mappings> …… </struts-config>

7、最后当然是最重要的分页代码了：Pager.java

java代码:

package com.xindeco.common; import java.util.* ; public class Pager {   private static int MAX_PAGE_INDEX = 10; //页脚显示多少页   private static String HEADER = "Result page";      public static String generate(int offset, int length, int size, String url) {         if (length > size) {           String pref;           if (url.indexOf("?") > -1) {                 pref = "&";           } else {                 pref = "?";           }           String header = "<font face='Helvetica' size='-1'>"+HEADER+": ";           if (offset > 0) {                 header += "&<a href=\""+url+pref+"pager.offset="+(offset-size)+"\">[<< Prev]</a>\n";           }           int start;           int radius = MAX_PAGE_INDEX/2*size;           if (offset < radius) {                 start = 0;           } else if(offset < length-radius) {                 start = offset - radius;           } else {                 start = (length/size-MAX_PAGE_INDEX)*size;           }           for(int i=start;i<length && i < start + MAX_PAGE_INDEX*size;i+=size) {                 if (i == offset) {                   header += "<b>"+(i/size+1)+"</b>\n";                 } else {                   header += "&<a href=\""+url+pref+"pager.offset="+i+"\">"+(i/size+1)+"</a>\n";                 }           }           if(offset < length - size) {                 header += "&<a href=\""+url+pref+"pager.offset="+((int)offset+(int)size)+"\">[Next >>]</a>\n";           }           header += "</font>";           return header;         } else {           return "";         }   } }

这部分代码的实现相当简洁，但已经足够完成所需了。