mysql通过limit实现分页功能

注：通过sql语句查询实现java类的分页效果，主要可以分为以下步骤：登录界面--->controller--->首页--->controller(第一次页面传过去的页码为null，因此在controller中需要处理null)--->访问dao层通过limit实现分页查询--->返回所需分页的页面。下面请参考具体代码！

1、创建PagBean类，分页所用到的一些基本属性

package com.besttone.pojo;

import java.util.List;

import org.springframework.stereotype.Component;

public class PageBean {

	private int pageSize = 10;// 每页显示多少条数据
	private int nowPage = 0;// 当前页码
	private int rowCount = 0;// 总行数
	private int pageCount = 0;// 总页数
	private List rowList;// 每页存放的结果集

	// getter/setter
	public int getPageSize() {
		return pageSize;
	}

	public void setPageSize(int pageSize) {
		this.pageSize = pageSize;
	}

	public int getNowPage() {
		return nowPage;
	}

	public void setNowPage(int nowPage) {
		this.nowPage = nowPage;
	}

	public int getRowCount() {
		return rowCount;
	}

	public void setRowCount(int rowCount) {
		this.rowCount = rowCount;
	}

	public int getPageCount() {
		this.pageCount = rowCount % pageSize == 0 ? rowCount / pageSize
				: rowCount / pageSize + 1;
		return pageCount;
	}

	public List getRowList() {
		return rowList;
	}

	public void setRowList(List rowList) {
		this.rowList = rowList;
	}

	public PageBean(int pageSize, int nowPage, int rowCount, int pageCount,
			List rowList) {
		super();
		this.pageSize = pageSize;
		this.nowPage = nowPage;
		this.rowCount = rowCount;
		this.pageCount = pageCount;
		this.rowList = rowList;
	}

	public PageBean() {
		super();
	}
	
}

2、Dao层，sql语句查询

 

 

package com.besttone.dao;

import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import com.besttone.pojo.PageBean;

@Repository
public class PageDao {
	
	public PageBean getPageBean() {
		return pageBean;
	}

	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}

	@Autowired
	private JdbcTemplate jdbcTemplate;

	public JdbcTemplate getJdbcTemplate() {
		return jdbcTemplate;
	}

	public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
		this.jdbcTemplate = jdbcTemplate;
	}

	/**
	 * 
	 * 

	 * 
created by 周斌 at 2017-7-20  上午9:39:47
	 * 

	 * 	@describe 获取总行数
	 *  @return
	 */
	public List> getAllCount(){
		String sql="select * from login";
		return this.getJdbcTemplate().queryForList(sql);
	}
	
	
	public PageBean getNowPage(int pageSize,int nowPage){
                PageBean pageBean = new PageBean();
		pageBean.setPageSize(pageSize);
		pageBean.setNowPage(nowPage);
		pageBean.setRowCount(getAllCount().size());
		String sql="select login.username,login.password from login limit "+(nowPage-1)*pageSize+","+pageSize;
		List> list = this.getJdbcTemplate().queryForList(sql);
		pageBean.setRowList(list);
		return pageBean;
	}

}

3、Controller类，处理页面传过来的参数，并调用Dao层方法同时将数据库中的取到的属性放在request中，返回页面视图

 

 

package com.besttone.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import com.besttone.dao.PageDao;
import com.besttone.pojo.PageBean;

@Controller
public class PageController {

	@Autowired
	private PageDao pageDao;

	@RequestMapping(value = "page/getPage")
	public String getPage(HttpServletRequest request,
			HttpServletResponse response) {
		String nowPages = request.getParameter("nowPage");
		System.out.println(nowPages);
		int pageSize = 5;
		int nowPage = 0;
		
		if (nowPages != null) {
			nowPage = Integer.parseInt(nowPages);
		}
		if(nowPages == null){
			nowPage=1;
		}
		
		PageBean pageBean = pageDao.getNowPage(pageSize, nowPage);
		request.setAttribute("pageBean", pageBean);
		request.setAttribute("list", pageBean.getRowList());
	//	request.setAttribute("nowPage", pageBean.getNowPage());
	/*	Object object = request.getAttribute("nowPage");
		int i = Integer.parseInt(object.toString());*/
	//	request.setAttribute("pageCount", pageBean.getPageCount());
		return "user";
	}

}

4、页面信息，主要关注分页操作的js代码和el表达式取到的页面

 

 

<%@page import="com.besttone.pojo.PageBean"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>











	
	
			

		

			
用户名
			
密码
			
操作
		
		

				
${e.username}
				
${e.password}
				
删除 | 授权
			
		
	
	首页
	上一页 
	第${pageBean.nowPage}页/
	共${pageBean.pageCount}页 
	下一页 ${msg}
	尾页

总结：1、js中的upPage()和downPage()方法是实现上一页和下一页，如果没有这两个方法，则当点击上一页的时候页码小于1的时候会就会出错，当点击下一页的时候，如果页码大于总页码的时候则会一直查询数据库，但数据库没有这些数据则会返回null；2、如果有必要请自行封装Dao方法，则只需要每次调用Dao方法进行sql语句拼接就可以了！