剑三宠物明教:用Hibernate+Struts实现分页

 
上个星期偶然的一次机会，帮别人忙做一个Hibernate得东西，正好自己也有兴趣学习学习(^_^)，对Hibernate基础掌握之后，于是乎自然而然想到了Paging问题。当时Google以下，大家都与Hibernate Paging 原理都转贴了不少，但是真正结合起来的例子然而很少(几乎没有)。那天在论坛看到一个兄弟求一个Hibernate+Struts实现分页得例子。于是昨天下午4点-6点开始着手（下班回家有天下足球阿！），后来晚上睡觉都在向这个问题（失眠才想的，不是因为想而失眠 ~郁闷）。今天上午来了看了几十封垃圾邮件后，终于作了出来（由不足的地方情大家指出）。在此鸣谢“Norther ”兄弟对我HQL的支持（才开始学哈，多谢好心人啊）。废话少说，开始写：前言，必读1：由于长促写的，难免有不周到或者还有格式上面凌乱的问题。
2：对于Page function进行了一定的封装。用户只需要在PageBean 里面设置以下pageRecorders （每页显示条数据），然后在自己的Action里面组装自己需要的query就可以了。
3：对于Hibernate没有进行深入研究（时间有限），所以采取了每次翻页都采用一次查询。第一次显示的时候采用了两次查询（第一次是查询Hibernate.xml里面设定的一次查询长度的所有纪录，由此推算出总数据数，总页数等等，然后赋予第一页的起始数和第一页的终止数，由query.list(); 得出第一页的数据，这里可能会有更好的改进，希望大家指点。后面得翻页主要是得到第N页的起始数和第N页的终止数）
4: 在此鸣谢各位兄弟的支持,
正文：
关于Hibernate得基本配置什么的就不多说了。现在就只是写上Paging相关的代码：
1:
PageBean.java
/*
* Created on 2006-3-21
*
* To change the template for this generated file go to
* Window>Preferences>Java>Code Generation>Code and Comments
*/
package com.ibm.hibernate.beans;import java.util.Iterator;
import java.util.List;import javax.servlet.http.HttpServletRequest;import net.sf.hibernate.HibernateException;
import net.sf.hibernate.Query;
import net.sf.hibernate.Session;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.Transaction;/**
* @author Johnny           //PS: My English Name
*
* To change the template for this generated type comment go to
* Window>Preferences>Java>Code Generation>Code and Comments
*/
public class PageBean {
//        public static final String HQL_DEMO_BYNAME =
//                "from com.ibm.hibernate.beans.Demo as e where e.name=:tempName";
//        public static final String HQL_DEMO_BYALL =
//                "from com.ibm.hibernate.beans.Demo as e ";        int currentPage = 1; //当前页
        public int totalPages = 0; //总页数
        int pageRecorders = 5; //每页5条数据
        int totalRows = 0; //总数据数
        int pageStartRow = 0; //每页的起始数
        int pageEndRow = 0; //每页显示数据的终止数
        boolean hasNextPage = false; //是否有下一页
        boolean hasPreviousPage = false; //是否有前一页
        List list;
        private Demo demo;
        Iterator it;
        static PageBean pb;        public PageBean() {
        }        public PageBean(List list) {
                this.list = list;
                totalRows = list.size();
                it = list.iterator();
                hasPreviousPage = false;
                currentPage = 1;
                if ((totalRows % pageRecorders) == 0) {
                        totalPages = totalRows / pageRecorders;
                } else {
                        totalPages = totalRows / pageRecorders + 1;
                }                if (currentPage >= totalPages) {
                        hasNextPage = false;
                } else {
                        hasNextPage = true;
                }                if (totalRows < pageRecorders) {
                        this.pageStartRow = 0;
                        this.pageEndRow = totalRows;
                } else {
                        this.pageStartRow = 0;
                        this.pageEndRow = pageRecorders;
                }        }        /**
         * @return Returns the currentPage.
         */
        public String getCurrentPage() {
                return this.toString(currentPage);
        }
        /**
         * @param currentPage The currentPage to set.
         */
        public void setCurrentPage(int currentPage) {
                this.currentPage = currentPage;
        }
        /**
         * @return Returns the pageRecorders.
         */
        public int getPageRecorders() {
                return pageRecorders;
        }
        /**
         * @param pageRecorders The pageRecorders to set.
         */
        public void setPageRecorders(int pageRecorders) {
                this.pageRecorders = pageRecorders;
        }
        /**
         * @return Returns the pageEndRow.
         */
        public int getPageEndRow() {
                return pageEndRow;
        }
        /**
         * @return Returns the pageStartRow.
         */
        public int getPageStartRow() {
                return pageStartRow;
        }
        /**
         * @return Returns the totalPages.
         */
        public String getTotalPages() {                return this.toString(totalPages);
        }
        /**
         * @return Returns the totalRows.
         */
        public String getTotalRows() {
                return this.toString(totalRows);
        }
        /**
         * @return Returns the hasNextPage.
         */
        public boolean isHasNextPage() {
                return hasNextPage;
        }
        /**
         * @param hasNextPage The hasNextPage to set.
         */
        public void setHasNextPage(boolean hasNextPage) {
                this.hasNextPage = hasNextPage;
        }
        /**
         * @return Returns the hasPreviousPage.
         */
        public boolean isHasPreviousPage() {
                return hasPreviousPage;
        }
        /**
         * @param hasPreviousPage The hasPreviousPage to set.
         */
        public void setHasPreviousPage(boolean hasPreviousPage) {
                this.hasPreviousPage = hasPreviousPage;
        }
        public void getNextPage() {                currentPage = currentPage + 1;
                System.out.println("PageBean.getNextPage()正在执行；");
                System.out.println("参数currentPage=" + currentPage);                if ((currentPage - 1) > 0) {
                        hasPreviousPage = true;
                } else {
                        hasPreviousPage = false;
                }                if (currentPage >= totalPages) {
                        hasNextPage = false;
                } else {
                        hasNextPage = true;
                }
                System.out.println("参数hasNextPage=" + hasNextPage);
                if (currentPage * pageRecorders < totalRows) { //判断是否为最后一页
                        pageEndRow = currentPage * pageRecorders;
                        pageStartRow = pageEndRow - pageRecorders;
                } else {
                        pageEndRow = totalRows;
                        pageStartRow = pageRecorders * (totalPages - 1);
                }
                System.out.println("参数pageStartRow=" + pageStartRow);
                System.out.println("参数pageEndRow=" + pageEndRow);
                //                Demo[] Demos = getDemos();
                this.description();        }        public void getPreviouspage() {                currentPage = currentPage - 1;                if (currentPage == 0) {
                        currentPage = 1;
                }                if (currentPage >= totalPages) {
                        hasNextPage = false;
                } else {
                        hasNextPage = true;
                }
                if ((currentPage - 1) > 0) {
                        hasPreviousPage = true;
                } else {
                        hasPreviousPage = false;
                }
                if (currentPage * pageRecorders < totalRows) { //判断是否为最后一页
                        pageEndRow = currentPage * pageRecorders;
                        pageStartRow = pageEndRow - pageRecorders;
                } else {
                        pageEndRow = totalRows;
                        pageStartRow = pageRecorders * (totalPages - 1);
                }
                System.out.println("参数pageStartRow=" + pageStartRow);
                System.out.println("参数pageEndRow=" + pageEndRow);
                this.description();        }        public String toString(int temp) {
                String str = Integer.toString(temp);
                return str;
        }        public void description() {                String description =
                        "共有数据数:"
                                + this.getTotalRows()
                                + "共有页数: "
                                + this.getTotalPages()
                                + "当前页数为:"
                                + this.getCurrentPage()
                                + " 是否有前一页: "
                                + this.isHasPreviousPage()
                                + " 是否有下一页:"
                                + this.isHasNextPage()
                                + " 开始行数:"
                                + this.getPageStartRow()
                                + " 终止行数:"
                                + this.getPageEndRow();                System.out.println(description);        }
        /**
         * @return
         */
        public Demo getDemo() {
                return demo;
        }        /**
         * @param demo
         */
        public void setDemo(Demo demo) {
                this.demo = demo;
        }        /**
         * @return
         */
        public List getList() {
                return list;
        }        /**
         * @param list
         */
        public void setList(List list) {
                this.list = list;
        }        /**
         *
         */
        public PageBean pagingFirsttime(
                SessionFactory factory,
                Session session,
                Transaction transaction,
                String name,
                Query query,
                List list,
                PageBean pb,
                HttpServletRequest request)
                throws HibernateException {                list = query.list();                pb = new PageBean(list);
                query.setFirstResult(pb.getPageStartRow());
                query.setMaxResults(pb.getPageRecorders());
                list = query.list();                pb.setList(list);
                pb.description();
               
                transaction.commit();
                session.close();
                return pb;        }
        public PageBean paging(
                SessionFactory factory,
                Session session,
                Transaction transaction,
                String name,
                Query query,
                List list,
                PageBean pb,
                HttpServletRequest request)
                throws HibernateException {
               
                query.setFirstResult(pb.getPageStartRow());
                query.setMaxResults(pb.getPageRecorders());
                list = query.list();                pb.setList(list);
                pb.description();
       
                transaction.commit();
                session.close();
               
                return pb;
        }} 
 PagingAction.java
/
*
* Created on 2006-3-21
*
* To change the template for this generated file go to
* Window>Preferences>Java>Code Generation>Code and Comments
*/
package com.ibm.hibernate.action;import java.util.ArrayList;
import java.util.List;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;import net.sf.hibernate.Hibernate;
import net.sf.hibernate.HibernateException;
import net.sf.hibernate.Query;
import net.sf.hibernate.Session;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.Transaction;import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;import com.ibm.hibernate.beans.Demo;
import com.ibm.hibernate.beans.PageBean;
import com.ibm.hibernate.form.QueryForm;
import com.strutsrecipes.hibernate.plugin.HibernatePlugIn;/**
* @author Johnny
*
* To change the template for this generated type comment go to
* Window>Preferences>Java>Code Generation>Code and Comments
*/
public class PagingAction extends Action {
        public static final String HQL_DEMO_BYNAME =
                "from com.ibm.hibernate.beans.Demo as e where e.name=:tempName";
        public static final String HQL_DEMO_BYALL =
                "from com.ibm.hibernate.beans.Demo as e ";
               
        public ActionForward execute(
                ActionMapping mapping,
                ActionForm form,
                HttpServletRequest request,
                HttpServletResponse response)
                throws HibernateException {                SessionFactory factory = null;
                Session session = null;
                Transaction transaction = null;
                Query query = null;
                List list = null;
                PageBean pb = (PageBean) request.getSession().getAttribute("page");
                String action = request.getParameter("action");                QueryForm queryForm = (QueryForm) form;
                String name = queryForm.getName();                try {
                        factory =
                                (SessionFactory) servlet.getServletContext().getAttribute(
                                        HibernatePlugIn.SESSION_FACTORY_KEY);
                        session = factory.openSession();
                        transaction = session.beginTransaction();
                        //组装Query
                        if (name == null || name.equals("")) {                                query = session.createQuery(HQL_DEMO_BYALL);                        } else {                                query = session.createQuery(HQL_DEMO_BYNAME);                                query.setString("tempName", name);                        }                        if (action == null || action.equals("null")) { //第一次读取数据
                                pb = new PageBean();
                                pb =
                                        pb.pagingFirsttime(
                                                factory,
                                                session,
                                                transaction,
                                                name,
                                                query,
                                                list,
                                                pb,
                                                request);                                System.out.println("第一步，数据已经成功传递到Action，action=" + action);                        } else {
                                if (action == "nextPage" || action.equals("nextPage")) {//nextPage
                                        System.out.println("参数action=" + action);
                                        System.out.println("函数pb.getNextPage()准备执行");                                        pb.getNextPage();
                                        pb =
                                                pb.paging(
                                                        factory,
                                                        session,
                                                        transaction,
                                                        name,
                                                        query,
                                                        list,
                                                        pb,
                                                        request);
                                }
                                if (action == "previousPage"
                                        || action.equals("previousPage")) {//previousPage
                                        System.out.println("参数action=" + action);
                                        System.out.println("函数pb.getNextPage()准备执行");                                        pb.getPreviouspage();
                                        pb =
                                                pb.paging(
                                                        factory,
                                                        session,
                                                        transaction,
                                                        name,
                                                        query,
                                                        list,
                                                        pb,
                                                        request);                                }
                        }
                } catch (Exception e) {
                        e.printStackTrace();
                        System.out.println("数据库连接出现异常");
                }
                request.setAttribute("page", pb);
                request.getSession().setAttribute("page", pb);
                return (mapping.findForward("QuerySuccess"));
        }}
Jsp 相关部分
                        type="com.ibm.hibernate.beans.Demo">                       
                                 
                                                                 
                                                                        onclick="transfervalue(‘<%=idint%>‘)">
                                                                        value="Modify">
               
       
               
       

PreviousPage                                         value="true">                         nextPage                                 Total Records:                 Total Pages:                 CurrentPage:

第一次查询的图片
，以及后面的图片

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msn: Johnny_issc@hotmail.com