通过sql语句limit标签生成java分页

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;

@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 {

@Autowired
private PageBean pageBean;

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;
}

/**
*
* <p>
* <h1>created by 周斌 at 2017-7-20  上午9:39:47</h1>
* <p>
* 	@describe 获取总行数
*  @return
*/
public List<Map<String, Object>> getAllCount(){
String sql="select * from login";
return this.getJdbcTemplate().queryForList(sql);
}

public PageBean getNowPage(int pageSize,int nowPage){
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<Map<String,Object>> 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 + "/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<base href="<%=basePath%>">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>显示用户</title>
<style type="text/css">
table {
border-collapse: collapse;
width: 90%;
height: 90%;
text-align: center;
}

a {
text-decoration: none;
color: #000;
}
</style>
<script type="text/javascript">
function upPage() {
var nowPage = '${pageBean.nowPage}';
if (nowPage < 2) {
nowPage == 1;
} else {
nowPage = nowPage - 1;
}
self.location.href = "page/getPage?nowPage=" + nowPage;
}

function downPage() {
var nowPage = '${pageBean.nowPage}';
var pageCount = '${pageBean.pageCount}';
if (nowPage >= pageCount) {
nowPage = pageCount;
} else {
nowPage = parseInt(nowPage) + 1;
}
self.location.href = "page/getPage?nowPage=" + nowPage;
}
</script>

</head>
<body>
<!-- <span>数据库显示页面</span> -->
<table border="1">
<tr>
<th>用户名</th>
<th>密码</th>
<th>操作</th>
</tr>
<c:forEach var="e" items="${list}">
<tr>
<td>${e.username}</td>
<td>${e.password}</td>
<td><a href="login/del?username=${e.username}"
onclick="return confirm('确定将此记录删除?')">删除</a> | <a><a
href="login/auth?userid=${e.userId}">授权</a></td>
</tr>
</c:forEach>
</table>
<span><a href="page/getPage?nowPage=1">首页</a></span>
<span><a href="javascript:upPage();">上一页</a></span> 
<span>第${pageBean.nowPage}页</span>/
<span>共${pageBean.pageCount}页</span> 
<span><a href="javascript:downPage();">下一页</a></span> ${msg}
<span><a href="page/getPage?nowPage=${pageBean.pageCount}">尾页</a></span>
</body>
</html>

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！