java--分页技术(2)

来源：互联网发布：投诉淘宝卖家电话多少编辑：程序博客网时间：2024/05/01 04:02

在http://blog.csdn.net/xanlv/article/details/53318076 java–分页技术(1)的基础上修改了一部分

show.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%><html>  <head>    <script type="text/javascript">        function sub(obj){            window.location.href="<c:url value='/page?pageNo="+obj.value+"'/>";        }    </script>  </head>  <body>    <h3>学生信息</h3>    <c:forEach items="${result.students}" var="s">        id=${s.id},,,name=${s.name}<br/>    </c:forEach>    pageCount=${result.pageCount}<br/>    showStart=${showStart},${showEnd}    <h2>////////////展示分页的分页////////////</h2>    <c:if test="${result.currentPage>1}">        <a href='<c:url value="/page?pageNo=${result.currentPage-1}"></c:url>'>上一页</a>&nbsp;    </c:if>    <c:forEach begin="${showStart}" end="${showEnd}" var="idx">        <c:if test="${result.currentPage==idx}">            ${idx}        </c:if>        <c:if test="${result.currentPage!=idx}">            <a href='<c:url value="/page?pageNo=${idx}"></c:url>'>${idx}</a>&nbsp;        </c:if>    </c:forEach>    <c:if test="${result.currentPage<result.pageCount}">        <a href='<c:url value="/page?pageNo=${result.currentPage+1}"></c:url>'>下一页</a>&nbsp;    </c:if>    <br/><br/>    <select onchange="sub(this)">        <c:forEach begin="1" end="${result.pageCount}" var="idx">            <%--                <option selected='<c:if test="${idx==result.currentPage}">selected</c:if>' value="${idx}">第${idx}页</option>             --%>            <option <c:if test="${idx==result.currentPage}">selected</c:if> value="${idx}">第${idx}页</option>        </c:forEach>    </select>    <h2>搜素</h2>    <form action="<c:url value='/page'/>" method="post">        ID中包含:<input type="text" name="id" value="${stud.id}"/>        Name中包含:<input type="text" name="name" value="${stud.name}"/>        <input type="submit"/>    </form>  </body></html>

PageServlet.java

package cn.hncu.servlet;import java.io.IOException;import java.util.Map;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.hncu.domain.Stud;import cn.hncu.service.IPageService;import cn.hncu.service.PageServiceImpl;public class PageServlet extends HttpServlet {    //依赖注入service    IPageService service=new PageServiceImpl();    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doPost(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        Stud stud=null;        if(request.getMethod().equals("GET")){//          System.out.println("det...");            //先看看session中有没有旧的查询条件值对象stud            stud=(Stud) request.getSession().getAttribute("stud");            if(stud==null){                stud=new Stud();            }        }else{            //System.out.println("post....");            //用Model封装查询条件---更好！            String id=request.getParameter("id");            String name=request.getParameter("name");            stud=new Stud();            stud.setId(id);            stud.setName(name);            request.getSession().setAttribute("stud", stud);        }        String pageNo=request.getParameter("pageNo");        if(pageNo==null||pageNo.equals("")){            pageNo="1";//默认查询第1页        }        try {            //把页码转成int            int iPageNo=Integer.parseInt(pageNo);            Map<String, Object> result=service.query(iPageNo,stud);            //这里需要注意把service层和dao层对应的此方法的修改//          System.out.println("--"+result.get("pageCount"));//          System.out.println("--"+result.get("students"));            //再补一个结果3: 当前页码            result.put("currentPage", iPageNo);            //////////////相比上一版本增加下面这段代码//////////////////////            //为实现分页的分页，只需在servlet中为前端补存:showStart和showEnd---显示的起始与终止页码            //分页的分页            int showSize=10;//每次显示几个页号            int showStart=1;//显示的起始页号//          int showEnd=showStart+showSize-1;            int showEnd=0;//显示的终止页号            int pageCount=Integer.valueOf(""+ result.get("pageCount"));            //如果所有页码不足showSize则:  showStart=1, showEnd=pageCount            if(showSize > pageCount){                showEnd=pageCount;                showStart=1;            }else{                System.out.println("iPageNo:"+iPageNo);                //计算起始页号                if(iPageNo<=(showSize/2)){                    showStart=1;                }else{                    showStart=iPageNo-(showSize/2);                }                //计算终止页号                showEnd=showStart+showSize-1;                if(showEnd>pageCount){                    showEnd=pageCount;                    showStart=pageCount-showSize+1;                }            }            request.setAttribute("showStart", showStart);            request.setAttribute("showEnd", showEnd);            //结果数据一定要放在容器中            request.setAttribute("result", result);            //转发到结果页面去显示            request.getRequestDispatcher("/jsps/show.jsp").forward(request, response);        } catch (NumberFormatException e) {            response.getWriter().println("页码格式错误!");        } catch (Exception e) {            response.getWriter().println("数据库查询错误!");        }    }}

PageDaoJdbc.java

package cn.hncu.dao;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.commons.dbutils.QueryRunner;import org.apache.commons.dbutils.handlers.MapListHandler;import org.apache.commons.dbutils.handlers.ScalarHandler;import cn.hncu.domain.Stud;import cn.hncu.pubs.C3p0Utils;public class PageDaoJdbc implements PageDAO {    @Override    public Map<String, Object> query(Integer iPageNo,Stud stud) throws Exception {        int pageSize=10;//每页显示20行，本例这里写死了        Map<String, Object> result=new HashMap<String,Object>();        //构造条件查询的sql,包含两条，一条用于查询总行数，另一条查数据行//      String sql_1="select count(1) from student where 1=1";        String sql_1="select count(1) from student where 1=1";//查询总行数        String sql_2="select * from student where 1=1";//查询当前页要显示的内容(数据行)        if(stud.getId()!=null&& !stud.getId().trim().equals("")){            sql_1+=" and id like '%"+stud.getId()+"%'";            sql_2+=" and id like '%"+stud.getId()+"%'";        }        if(stud.getName()!=null&& !stud.getName().trim().equals("")){            sql_1+=" and name like '%"+stud.getName()+"%'";            sql_2+=" and name like '%"+stud.getName()+"%'";        }        System.out.println("sql_1:"+sql_1);        QueryRunner run=new QueryRunner(C3p0Utils.getDataSource());        Object obj=run.query(sql_1, new ScalarHandler());//使用ScalarHandler封装返回结果是1行1列的数据        System.out.println("pageCount:"+obj.toString());        int rows=Integer.parseInt(obj.toString());        //计算出总页数//      int pageCount=rows/iPageNo+rows%iPageNo==0?0:1;        int pageCount=rows/pageSize+(rows%pageSize==0?0:1);        result.put("pageCount", pageCount);//结果1        System.out.println("row:"+rows);        System.out.println("pageCount:"+pageCount);        int startN = (iPageNo-1)*pageSize;//从哪一行开始显示//      if(startN==0){//          startN=1;//      }        sql_2+=" limit "+startN+","+pageSize;//      System.out.println("sql_2:"+sql_2);        //查询当前页要显示的内容(数据行)//      List<Map<String, String>> students=run.query(sql_2, new MapListHandler());//error        List<Map<String, Object>> students=run.query(sql_2, new MapListHandler());//      System.out.println(students);        result.put("students", students);//结果2//      System.out.println("ll"+result.get("students"));        return result;    }}

首页
这里写图片描述
中页

尾页

展示查询–首页
这里写图片描述
展示查询–尾页

0 0