802~805 分页 分析，分析具体步骤 实现前后台编码
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分页分析：
分析具体步骤：
package com.example.web.servlet;
import com.example.domain.PageBean;
import com.example.domain.User;
import com.example.service.UserService;
import com.example.service.impl.UserServiceImpl;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Map;
@WebServlet("/findUserByPageServlet")
public class FindUserByPageServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
//1.获取参数
String currentPage = request.getParameter("currentPage");//当前页码
String rows = request.getParameter("rows");//每页显示条数
if(currentPage == null || "".equals(currentPage)){
currentPage = "1";
}
if(rows == null || "".equals(rows)){
rows = "5";
}
//获取条件查询参数
Map<String, String[]> condition = request.getParameterMap();
//2.调用service查询
UserService service = new UserServiceImpl();
PageBean<User> pb = service.findUserByPage(currentPage,rows);
System.out.println(pb);
//3.将PageBean存入request
request.setAttribute("pb",pb);
request.setAttribute("condition",condition);//将查询条件存入request
//4.转发到list.jsp
request.getRequestDispatcher("/list.jsp").forward(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
PageBean<User> findUserByPage(String currentPage, String rows);
=====
@Override
public PageBean<User> findUserByPage(String _currentPage, String _rows) {
int currentPage = Integer.parseInt(_currentPage);
int rows = Integer.parseInt(_rows);
if(currentPage <=0){
currentPage = 1 ;
}
//1.创建空的PageBean对象
PageBean<User> pb = new PageBean<User>();
//2.设置参数
pb.setCurrentPage(currentPage);
pb.setRows(rows);
//3.调用dao查询总记录数
int totalCount = dao.findTotalCount();
pb.setTotalCount(totalCount);
//4.调用dao查询List集合
//记录开始的记录索引
int start = (currentPage - 1)* rows;
List<User> list = dao.findByPage(start,rows);
pb.setList(list);
//计算总页码
int totalPage = (totalCount % rows) == 0? totalCount/rows : (totalCount/rows)+1;
pb.setTotalPage(totalPage);
return pb;
}
=====
List<User> findByPage(int start, int rows);//分页查询每页记录
=====
@Override
public int findTotalCount() {
String sql = "select count(*) from user";
return template.queryForObject(sql,Integer.class);
}
@Override
public List<User> findByPage(int start, int rows) {
String sql = "select *from user limit ? , ?";
return template.query(sql,new BeanPropertyRowMapper<User>(User.class),start,rows);
}
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<!-- 网页使用的语言 -->
<html lang="zh-CN">
<head>
<!-- 指定字符集 -->
<meta charset="utf-8">
<!-- 使用Edge最新的浏览器的渲染方式 -->
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<!-- viewport视口：网页可以根据设置的宽度自动进行适配，在浏览器的内部虚拟一个容器，容器的宽度与设备的宽度相同。
width: 默认宽度与设备的宽度相同
initial-scale: 初始的缩放比，为1:1 -->
<meta name="viewport" content="width=device-width, initial-scale=1">
<!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
<title>用户信息管理系统</title>
<!-- 1. 导入CSS的全局样式 -->
<link href="css/bootstrap.min.css" rel="stylesheet">
<!-- 2. jQuery导入，建议使用1.9以上的版本 -->
<script src="js/jquery-2.1.0.min.js"></script>
<!-- 3. 导入bootstrap的js文件 -->
<script src="js/bootstrap.min.js"></script>
<style type="text/css">
td, th {
text-align: center;
}
</style>
<script>
function deleteUser(id){
//用户安全提示
if(confirm("确定删除嘛？")){
location.href="${pageContext.request.contextPath}/delUserServlet?id="+id;
}
}
window.onload = function () {
document.getElementById("delSelected").onclick = function () {
if (confirm("数据一但删除无法恢复")){
//提交表单
document.getElementById("form").submit();
}
}
//1.获取第一个cb
document.getElementById("firstCb").onclick = function(){
//2.获取下边列表中所有的cb
var cbs = document.getElementsByName("uid");
//3.遍历
for (var i = 0; i < cbs.length; i++) {
//4.设置这些cbs[i]的checked状态 = firstCb.checked
cbs[i].checked = this.checked;
}
}
}
</script>
</head>
<body>
<div class="container">
<h3 style="text-align: center">用户信息列表</h3>
<div style="float: left">
<form class="form-inline">
<div class="form-group">
<label for="exampleInputName2">姓名</label>
<input type="text" class="form-control" id="exampleInputName2">
</div>
<div class="form-group">
<label for="exampleInputName3">籍贯</label>
<input type="text" class="form-control" id="exampleInputName3">
</div>
<div class="form-group">
<label for="exampleInputEmail2">邮箱</label>
<input type="email" class="form-control" id="exampleInputEmail2">
</div>
<button type="submit" class="btn btn-default">查询</button>
</form>
</div>
<div style="float: right; margin: 5px ">
<a class="btn btn-primary" href="${pageContext.request.contextPath}/add.jsp">添加联系人</a>
<a class="btn btn-primary" href="javascript:void(0);" id="delSelected">删除选中</a>
</div>
<form id="form" action="${pageContext.request.contextPath}/delSelectedServlet" method="post">
<table border="1" class="table table-bordered table-hover">
<tr class="success">
<th><input type="checkbox" id="firstCb"></th>
<th>编号</th>
<th>姓名</th>
<th>性别</th>
<th>年龄</th>
<th>籍贯</th>
<th>QQ</th>
<th>邮箱</th>
<th>操作</th>
</tr>
<c:forEach items="${pb.list}" var="user" varStatus="s">
<tr>
<td><input type="checkbox" name="uid" value="${user.id}"></td>
<td>${s.count}</td>
<td>${user.name}</td>
<td>${user.gender}</td>
<td>${user.age}</td>
<td>${user.address}</td>
<td>${user.qq}</td>
<td>${user.email}</td>
<td><a class="btn btn-default btn-sm" href="${pageContext.request.contextPath}/findUserServlet?id=${user.id}">修改</a>
<a class="btn btn-default btn-sm" href="javascript:deleteUser(${user.id})">删除</a></td>
</tr>
</c:forEach>
</table>
</form>
<div>
<nav aria-label="Page navigation">
<ul class="pagination">
<c:if test="${pb.currentPage==1}">
<li class="disabled">
</c:if>
<c:if test="${pb.currentPage !=1}">
<li>
</c:if>
<a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${pb.currentPage - 1}&rows=5" aria-label="Previous">
<span aria-hidden="true">«</span>
</a>
</li>
<c:forEach begin="1" end="${pb.totalPage}" var="i">
<c:if test="${pb.currentPage == i}">
<li class="active"><a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${i}&rows=5">${i}</a></li>
</c:if>
<c:if test="${pb.currentPage != i}">
<li><a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${i}&rows=5">${i}</a></li>
</c:if>
</c:forEach>
<li>
<a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${pb.currentPage + 1}&rows=5" aria-label="Next">
<span aria-hidden="true">»</span>
</a>
</li>
<span style="font-size: 25px;margin-left: 5px">
共${pb.totalCount}条记录共${pb.totalPage}页
</span>
</ul>
</nav>
</div>
</div>
</body>
</html>
package com.example.domain;
import java.util.List;
/**
* 分页对象
*/
public class PageBean<T>{
private int totalCount; // 总记录数
private int totalPage ; // 总页码
private List<T> list ; // 每页的数据
private int currentPage ; //当前页码
private int rows;//每页显示的记录数
@Override
public String toString() {
return "PageBean{" +
"totalCount=" + totalCount +
", totalPage=" + totalPage +
", list=" + list +
", currentPage=" + currentPage +
", rows=" + rows +
'}';
}
public int getTotalCount() {
return totalCount;
}
public void setTotalCount(int totalCount) {
this.totalCount = totalCount;
}
public int getTotalPage() {
return totalPage;
}
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}
public List<T> getList() {
return list;
}
public void setList(List<T> list) {
this.list = list;
}
public int getCurrentPage() {
return currentPage;
}
public void setCurrentPage(int currentPage) {
this.currentPage = currentPage;
}
public int getRows() {
return rows;
}
public void setRows(int rows) {
this.rows = rows;
}
}
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