分页显示——(一)

分页显⽰——（⼀）

1.思路介绍:

先定义⼀个封装分页数据的泛型⼯具类，控制层中通过前台传的页数与每页的数量向service要page对象，service层调⽤dao返回总数并调⽤dao取出数据(limit关键字)，dao层从数据库中取出service层所需要的数据，并提交给service层。这样就达到分页的效果。数据封装在pageBean的list中

2.PageBean⼯具类(泛型类)

package utils;

/**

* 分页⼯具类

import java.util.ArrayList;

import java.util.List;

public class PageBean<T> {

//当前页

private int currentPage;

//当前页显⽰的条数

private int currentCount;

//总条数

private int totalCount;

//总页数

private int totalPage;

//每页显⽰的数据

private List<T> productList = new ArrayList<T>();

public int getCurrentPage() {

return currentPage;

}

public void setCurrentPage(int currentPage) {

this.currentPage = currentPage;

}

public int getCurrentCount() {

return currentCount;

}

public void setCurrentCount(int currentCount) {

this.currentCount = currentCount;

}

public int getTotalCount() {

return totalCount;

}

public void setTotalCount(int totalCount) {

}

public int getTotalPage() {

return totalPage;

}

public void setTotalPage(int totalPage) {

}

public List<T> getProductList() {

return productList;

}

public void setProductList(List<T> productList) {

this.productList = productList;

}

3 . 控制层中通过前台传的页数与每页的数量向service要page对象package web;

import java.io.IOException;

分页预览

import java.sql.SQLException;

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 daomain.User;

import service.UserService;

import utils.PageBean;

@WebServlet("/userfenye")

public class Userfenye extends HttpServlet {

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

UserService service = new UserService();

//模拟当前是第⼀页，如果刚进来显⽰第⼀页数据

String currentPageStr = Parameter("currentPage");

if(currentPageStr==null) currentPageStr="1";

int currentPage = Integer.parseInt(currentPageStr);

//认为每页显⽰12条，后期可以根据⽤户输⼊设置每页显⽰的页数

int currentCount = 8;

PageBean<User> pageBean = null;

try {

pageBean = service.findPageBean(currentPage,currentCount);

} catch (SQLException e) {

e.printStackTrace();

}

request.setAttribute("pageBean", pageBean);

System.out.ProductList());

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doGet(request, response);

}

4. service层调⽤dao返回总数并调⽤dao取出数据(limit关键字) package service;

import java.sql.SQLException;

import java.util.List;

import daomain.User;

import utils.PageBean;

public class UserService {

private UserDao userDao;

//谁调⽤服务谁创建dao

public UserService() {

userDao = new UserDao();

}

public PageBean<User> findPageBean(int currentPage, int currentCount) throws SQLException { //⽬的：就是想办法封装⼀个PageBean 并返回

PageBean<User> pageBean = new PageBean();

//1、当前页private int currentPage;

pageBean.setCurrentPage(currentPage);

//2、当前页显⽰的条数private int currentCount;

pageBean.setCurrentCount(currentCount);

//3、总条数private int totalCount;

int totalCount = TotalCount();

pageBean.setTotalCount(totalCount);

//4、总页数private int totalPage;

* 总条数当前页显⽰的条数总页数

* 10 4 3

* 11 4 3

* 12 4 3

* 13 4 4

* 公式：总页数=il(总条数/当前显⽰的条数)

int totalPage = (int) il(1.0*totalCount/currentCount);

pageBean.setTotalPage(totalPage);

//5、每页显⽰的数据private List<T> productList = new ArrayList<T>();

* 页数与limit起始索引的关系

* 例如每页显⽰4条

* 页数其实索引每页显⽰条数

* 1 0 4

* 2 4 4

* 3 8 4

* 4 12 4

* 索引index = (当前页数-1)*每页显⽰的条数

int index = (currentPage-1)*currentCount;

List<User> userList = userDao.findUserListForPageBean(index,currentCount);

pageBean.setProductList(userList);

System.out.println(userList);

return pageBean;

}

5.dao层从数据库中取出service层所需要的数据，并提交给service层

(如果是最后⼀页的话，limit超出后只会取剩下的)

package dao;

import java.sql.SQLException;

import org.apachemons.dbutils.QueryRunner;

import org.apachemons.dbutils.handlers.BeanHandler;

import org.apachemons.dbutils.handlers.BeanListHandler;

import org.apachemons.dbutils.handlers.ScalarHandler;

import daomain.User;

import utils.DataSourceUtils;

/**

* @author: qlq

* @date : 2017年7⽉6⽇上午11:57:56

* @description:chuli yonghu xinxi

public class UserDao {

//获得全部的⽤户条数，返回⼀个整数

public int getTotalCount() throws SQLException {

QueryRunner runner = new DataSource());

String sql = "select count(*) from user";

Long query = (Long) runner.query(sql, new ScalarHandler());

return query.intValue();

}

public List<User> findUserListForPageBean(int index, int currentCount) throws SQLException { QueryRunner runner = new DataSource());

String sql = "select * from user limit ?,?";

return runner.query(sql, new BeanListHandler<User>(User.class), index,currentCount);

}

6.使⽤分页插件在页⾯进⾏显⽰

1. bootstrap分页插件使⽤简单，超过⼗个以上的页码显⽰是个问题

1.1 使⽤规则:

⾸先需要引⼊bootstrap的css和Jquery等三个⽂件

1.2 页⾯中使⽤显⽰分页标签

<%--items⽤于迭代的变量，var代表每次迭代之后存放名字 --%>

<tr>

</tr>

<c:forEach items="${pageBean.productList }" var="user">

<tr>

<th><img alt=""

src="${tPath }/${user.picture}"

></th>

<th>${user.password}</th>

</tr>

</table>

<div >

<c:if test="${pageBean.currentPage==1 }">

<li class="disabled"><a href="javascript:void(0);"

aria-label="Previous"><span aria-hidden="true">«</span>

</a></li>

</c:if>

<c:if test="${pageBean.currentPage!=1 }">

<li><a

href="${tPath }/userfenye?currentPage=${pageBean.currentPage-1}" aria-label="Previous"><span aria-hidden="true">«</span>

</a></li>

</c:if>

<c:forEach begin="1" end="${alPage }" var="page">

<c:if test="${pageBean.currentPage==page }">

</c:if>

<c:if test="${pageBean.currentPage!=page }">

<li><a

href="${tPath }/userfenye?currentPage=${page}">${page}</a></li> </c:if>

</c:forEach>

<c:if test="${pageBean.currentPage==alPage }">

<li class="disabled"><a href="javascript:void(0);"

aria-label="Next"><span aria-hidden="true">»</span>

</a></li>

</c:if>

<c:if test="${pageBean.currentPage!=alPage }">

<li><a

href="${tPath }/userfenye?currentPage=${pageBean.currentPage+1}" aria-label="Next"><span aria-hidden="true">»</span>

</a></li>

</c:if>

</ul>

</div>

1.3 效果

分页显示——(一)

发布评论取消回复

最近发表

热门文章

标签列表