分页的总体思想:
分页包含什么:
1.当前页,每页显示的记录数,总的记录数,总的页码,集合List存放的是JavaBean,首页, 尾页,上一页,下一页
传递的參数:当前页,每页显示的记录数.这两个本来就是有的。
数据库中查询的:总的记录数,集合List存放的是JavaBean。这两个是从数据库中查询的。
通过已知的属性计算:首页,
尾页,上一页,下一页,总的页码 这些是通过计算得到了。
因此javaBean Page能够写成:
package com.itheima.domain; import java.util.List; public class Page { private int thispage;//当前页 private int rowperpage;//每页显示的记录数 private int countrow;//总的记录数 private int countpage;//总的页数 private int firstpage;//首页 private int lastpage;//尾页 private int prepage;//上一页 private int nextpage;//下一页 private List<Customer> list; public int getThispage() { return thispage; } public void setThispage(int thispage) { this.thispage = thispage; } public int getRowperpage() { return rowperpage; } public void setRowperpage(int rowperpage) { this.rowperpage = rowperpage; } public int getCountrow() { return countrow; } public void setCountrow(int countrow) { this.countrow = countrow; } public int getCountpage() { return countpage; } public void setCountpage(int countpage) { this.countpage = countpage; } public int getFirstpage() { return firstpage; } public void setFirstpage(int firstpage) { this.firstpage = firstpage; } public int getLastpage() { return lastpage; } public void setLastpage(int lastpage) { this.lastpage = lastpage; } public int getPrepage() { return prepage; } public void setPrepage(int prepage) { this.prepage = prepage; } public int getNextpage() { return nextpage; } public void setNextpage(int nextpage) { this.nextpage = nextpage; } public List<Customer> getList() { return list; } public void setList(List<Customer> list) { this.list = list; } }
2.首先要进行分页须要在cn.itheima.web包中写一个分页的Servlet,PageCustomerServlet
这个类的主要步骤是:
(1).得到传递的參数默认是首页
(2).每页显示的记录数,这里默认的是5
(3).调用service中分页的函数返回Page
(4).将Page放到request域中
(5).重定向到要实现分页的jsp进行显示分页
package com.itheima.web; import java.io.IOException; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.itheima.domain.Customer; import com.itheima.domain.Page; import com.itheima.factory.BasicFactory; import com.itheima.service.CustomerService; public class PageCustomerServlet extends HttpServlet { CustomerService service =BasicFactory.getFactory().getInstance(CustomerService.class); public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.获取当前页每页显示的记录 int thispage=Integer.parseInt(request.getParameter("thispage")); int rowperpage=5; //2.调用service的方法 Page page=service.findCustomerByPage(thispage,rowperpage); request.setAttribute("page", page); //3.请求转发到pageList.jsp request.getRequestDispatcher("/pageList.jsp").forward(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
3.service实现类代码主要完毕的功能:
计算Page中的属性,设置到Page中
public Page findCustomerByPage(int thispage, int rowperpage) { Page page=new Page(); //设置当前页 page.setThispage(thispage); //每页显示的记录数 默认是5条 page.setRowperpage(rowperpage); //查询数据库一共同拥有多少行 int countrow=dao.getCount(); page.setCountrow(countrow); //一共同拥有多少页 int countpage=(countrow-1)/rowperpage+1; page.setCountpage(countpage); //设置首页 page.setFirstpage(1); //设置尾页 page.setLastpage(countpage); //前一页 page.setPrepage(thispage==1?1:thispage-1); //下一页 page.setNextpage(thispage==countpage?countpage:thispage+1); // List<Customer> list=dao.getCustomerByPage((thispage-1)*rowperpage,rowperpage); page.setList(list); return page; }
4.数据库中使用limitkeyword进行查询
public List<Customer> getCustomerByPage(int from, int count) { String sql="select * from customer limit ?,?"; QueryRunner runner=new QueryRunner(DataSourceUtil.getSource()); try { return runner.query(sql, new BeanListHandler<Customer>(Customer.class),from,count); } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(); } }
5.jsp页面中显示:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <script type="text/javascript"> function selectAll(all){ var del=document.getElementsByName("del"); for(var i=0;i<del.length;i++){ del[i].checked=all.checked; } } </script> <title></title> <meta http-equiv=" pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> </head> <body style="text-align: center"> <h1>客户管理系统_显示列表</h1><hr> <div align="center"> <form action="${pageContext.request.contextPath }/servlet/FindCustomerByConditionServlet" method="post"> 姓名:<input type="text" name="name" value="${param.name }"/> 性别:<input type="radio" name="gender" value="男" <c:if test="${param.gender==‘男‘}">checked="checked"</c:if> />男 <input type="radio" name="gender" value="女" <c:if test="${param.gender==‘女‘}">checked="checked"</c:if> />女 客户类型: <select name="type"> <option value=""/> <option value="钻石用户" <c:if test="${param.type==‘钻石用户‘}">selected="selected"</c:if> >钻石用户</option> <option value="黄金用户" <c:if test="${param.type==‘黄金用户‘}">selected="selected"</c:if> >黄金用户</option> <option value="普通用户" <c:if test="${param.type==‘普通用户‘}">selected="selected"</c:if> >普通用户</option> </select> <input type="submit" value="条件查询"> </form> <form action="${pageContext.request.contextPath}/servlet/BatchDeleteCustomer" method="post"> <table border="1" width="100%" cellpadding="0" cellspacing="0" style="text-align: center"> <tr> <th><input type="checkbox" onclick="selectAll(this)">全选</th> <th>客户姓名</th> <th>客户性别</th> <th>客户生日</th> <th>客户电话</th> <th>电子邮箱</th> <th>客户爱好</th> <th>客户类型</th> <th>具体描写叙述</th> <th colspan="2">操作类型</th> </tr> <c:forEach items="${requestScope.page.list}" var="li"> <tr> <td><input type="checkbox" name="del" value="${li.id}"/></td> <td><c:out value="${li.name}"></c:out></td> <td><c:out value="${li.gender}"></c:out></td> <td><c:out value="${li.birthday }"></c:out></td> <td><c:out value="${li.cellphone }"></c:out></td> <td><c:out value="${li.email }"></c:out></td> <td><c:out value="${li.preference }"></c:out></td> <td><c:out value="${li.type }"></c:out></td> <td><c:out value="${li.description }"></c:out></td> <td><a href="${pageContext.request.contextPath }/servlet/CustomerInfoServlet?id=${li.id}">改动</a></td> <td><a href="${pageContext.request.contextPath }/servlet/DeleteCustomerServlet?id=${li.id}">删除</a></td> </tr> </c:forEach> </table> <input type="submit" value="批量删除"/> </form> </div> ${requestScope.page.countrow }条数据 共${requestScope.page.countpage} 页 <a href="${pageContext.request.contextPath }/servlet/PageCustomerServlet?thispage=${page.firstpage}">首页</a> <a href="${pageContext.request.contextPath }/servlet/PageCustomerServlet?thispage=${page.prepage}">上一页</a> <!-- 分页逻辑 --> <c:if test="${page.countpage<=5}"> <c:set var="begin" value="1" scope="page"></c:set> <c:set var="end" value="${page.countpage}" scope="page"></c:set> </c:if> <c:if test="${page.countpage>5}"> <c:choose> <c:when test="${page.thispage<=3}"> <c:set var="begin" value="1" scope="page"></c:set> <c:set var="end" value="5" scope="page"></c:set> </c:when> <c:when test="${page.thispage>=page.countpage-2}"> <c:set var="begin" value="${page.countpage-4}" scope="page"></c:set> <c:set var="end" value="${page.countpage}" scope="page"></c:set> </c:when> <c:otherwise> <c:set var="begin" value="${page.thispage-2}" scope="page"></c:set> <c:set var="end" value="${page.thispage+2}" scope="page"></c:set> </c:otherwise> </c:choose> </c:if> <c:forEach begin="${begin}" end="${end}" step="1" var="i"> <c:if test="${i==page.thispage}"><!-- 当前页就不是超链接 --> <font color="black">${i}</font> </c:if> <c:if test="${i!=page.thispage}"><!-- 非当前页就是超链接 --> <a href="${pageContext.request.contextPath }/servlet/PageCustomerServlet? thispage=${i}"><font color="red">${i}</font></a> </c:if> </c:forEach> <!-- 分页逻辑结束 --> <a href="${pageContext.request.contextPath }/servlet/PageCustomerServlet?thispage=${page.nextpage}">下一页</a> <a href="${pageContext.request.contextPath }/servlet/PageCustomerServlet?thispage=${page.lastpage}">尾页</a> </body><br> <a href="${pageContext.request.contextPath }/">返回到主页</a> </html>
分页伪代码:
6.分页展示:
时间: 2024-10-14 18:49:32