分页查询功能图
PageBean 对象
int totalCount; //总记录数 int totalPage; //总页码 =总记录数%每页显示条数 == 0 ？总记录数/每页显示条数 ：总记录数/每页显示条数+1 List list; //每页数据list集合 int currentPage; //当前页码 int rows;
totalCount=select count(*) from user; totalPage=每页显示条数给服务器：rows list=select * from user limit ? ?; 第一个？ ：开始查询的索引 第二 ？：rows每页显示的条数 currentPage=提供当前页码给服务器 开始查询的索引=（currentPage-1）*rows 展示的一个例子 1 0 5 2 5 5 3 10 5 4 15 5
可以看出输入的两个参数是 currrentPage和rows;
业务逻辑流程
| FindUserByPageServlet
1接受请求参数 currentPage ,rows 2调用Service查询PageBean 3将PageBean 存入request 4转发list.jsp展示 | |
|- UserService
PageBean<User> findUserByPage(int currentPage,int rows){ //1创建空的PageBean对象 //2设置当前页面属性和rows属性 //3调用dao查询totalCount总记录数 dao.findTotalCount(); //4 start=(currentPage-1)*rows; //5调用dao查询list集合 dao.findByPage(int start,int rows) //6计算总页码 //7返-|--|
|
UserDao
//查询总记录数 int fingTotalCount() //分页查询List List findByPage（int start,int rows） | |
开始写代码具体步骤
后端代码编写
（代码中的红色字体是没有导入包）
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 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; } @Override public String toString() { return "PageBean{" + "totalCount=" + totalCount + ", totalPage=" + totalPage + ", list=" + list + ", currentPage=" + currentPage + ", rows=" + rows + '}'; } }
建立FindUserByPageServlet
@WebServlet( "/findUserByPageServlet") public class FindUserByPageServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1获取参数 String currentPage = request.getParameter("currentPage"); String rows = request.getParameter("rows"); if (currentPage == null || "".equals(currentPage)){ currentPage ="1"; } if (rows ==null || "".equals(rows)){ rows="5"; } //2调用service查询 UserService service=new UserServiceImpl(); PageBean<User> pb=service.findUserByPage(int currentPage,int rows); //3将PageBean存入request request.setAttribute("pb",pb); //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); } }
建立，编写UserService接口和UserServiceImpl；
public interface UserService { public PageBean<User> findUserByPage(int currentPage,int rows); }
public class UserServiceImpl implements UserService { @Override public PageBean<User> findUserByPage(int currentPage, int rows) { int rows = Integer.parseInt(_rows); int currentPage = Integer.parseInt(_currentPage); if (currentPage<=0){ currentPage=1; } //1创建空对象 PageBean<User> pb = new PageBean<User>(); //2设置参数 pb.setCurrentPage(currentPage); pb.setRows(rows); //3使用dao查询总记录数 int totalCount=dao.findTotalCount(); pb.setTotalCount(totalCount); //4使用dao查询list //计算开始的记录索引 int start=(currentPage-1)*rows; List<User> list=dao.findByPage(start,rows); pb.setList(list); //5计算总页码 int totalPage=(totalCount %rows)==0? totalCount/rows:(totalCount/rows)+1; pb.setTotalPage(totalPage); return pb; } }
创建UserDao接口和UserDaoImpl实现类；
public interface UserDao { //查询总记录数 int findTotalCount(); //分页查询总记录i数 List<User> findByPage(int start, int rows); }
public class UserDaoimpl implements UserDao { @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); } }
前端代码编写
<%@ 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("您确定要删除吗？")){ //访问路径 location.href="${pageContext.request.contextPath}/delUserServlet?id="+id; } } window.onload=function () { //给删除选中添加单击时间 document.getElementById("delSelected").onclick=function () { var flag=false; if(confirm("您确定要删除吗？")){ var cbs = document.getElementsByName("uid"); for(var i=0;i<cbs.length;i++){ if(cbs[i].checked){ flag=true; break; } } if (flag) { //访问路径 document.getElementById("from").submit(); } } } //1获取第一个cb document.getElementById("firstCb").onclick=function () { //获取下边列表中 =得cb var cbs = document.getElementsByName("uid"); for(var i=0;i<cbs.length;i++){ //设置这些cbs得checked状态=firstCb.check cbs[i].checked=this.checked; } } } </script> </head> <body> <div class="container"> <h3 style="text-align: center">用户信息列表</h3> <div style="float: left;"> <form class="form-inline" action="${pageContext.request.contextPath}/findUserByPageServlet" method="post"> <div class="form-group"> <label for="exampleInputName2">姓名</label> <input type="text" name="name" value="${condition.name[0]}" class="form-control" id="exampleInputName2" > </div> <div class="form-group"> <label for="exampleInputName3">籍贯</label> <input type="text" name="address" value="${condition.address[0]}" class="form-control" id="exampleInputName3" > </div> <div class="form-group"> <label for="exampleInputEmail2">邮箱</label> <input type="text" name="email" value="${condition.email[0]}" class="form-control" id="exampleInputEmail2" > </div> <button type="submit" class="btn btn-default">查询</button> </form> </div> <div style="float: right;margin: 5px"> <a class="btn btn-primary" href="${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="from" 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> <th><input type="checkbox" name="uid" value="${user.id}"></th> <td>${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(${user.id});">删除</a></td> </tr> </c:forEach> <%-- <tr>--%> <%-- <td colspan="8" align="center"><a class="btn btn-primary" href="add.html">添加联系人</a></td>--%> <%-- </tr>--%> </table> </form> <div> <nav aria-label="Page navigation"> <%-- 第一页禁用--%> <ul class="pagination"> <c:if test="${pb.currentPage==1}"> <li class="disabled"> </c:if> <c:if test="${pb.currentPage!=1}"> <li > </c:if> <%-- 当前页码减一页--%> <li> <a href="${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> <%-- 当前页码加一页--%> <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>
