首先先看效果图:
分页查询.png
然后提供了一个Java Bean实体类对象
(PageBean.java)
import java.util.List;
/**
* 封装了 分页查询的所有参数
*
*/
public class PageBean<T> {
private Integer cp; // 当前页
private Integer tp; // 总页数
private Integer tr; // 总记录数
private Integer pr; // 每页记录数为5
private List<T> list; // 每页数据
public Integer getCp() {
return cp;
}
public void setCp(Integer cp) {
this.cp = cp;
}
// 得到总页数
public Integer getTp() {
int count = tr / pr;
return (tr % pr == 0) ? count : count + 1;
}
public Integer getTr() {
return tr;
}
public void setTr(Integer tr) {
this.tr = tr;
}
public Integer getPr() {
return pr;
}
public void setPr(Integer pr) {
this.pr = pr;
}
public List<T> getList() {
return list;
}
public void setList(List<T> list) {
this.list = list;
}
}
在dao层提供对数据库的操作:()
/**
* 查询所有用户
*
* @return 返回封装了所有客户的list集合
* @throws Exception
*/
public PageBean<Customer> findAllCustomer(PageBean pageBean) throws Exception {
String sql = "select * from customer limit ?, ?";
Object[] objs = {(pageBean.getCp() - 1) * pageBean.getPr(),
pageBean.getPr()}; // 第一个参数为 5 * (当前页数 - 1); 后一个参数为5(每页的记录数)
List<Customer> list = qr.query(sql, new BeanListHandler<Customer>(Customer.class), objs);
pageBean.setList(list);
// 查询总记录数
sql = "select count(*) from customer";
Number n = (Number) qr.query(sql, new ScalarHandler());
Integer tr = n.intValue();
pageBean.setTr(tr);
return pageBean;
}
然后是页面的展示:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>客户列表</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
<h3 align="center">客户列表</h3>
<table border="1" width="70%" align="center">
<tr>
<th>客户姓名</th>
<th>性别</th>
<th>生日</th>
<th>手机</th>
<th>邮箱</th>
<th>描述</th>
<th>操作</th>
</tr>
<c:forEach var="customer" items="${requestScope.pageBean.list }">
<input type="hidden" value="${customer.cid }" id="cid"/>
<input type="hidden" value="${customer.cname }" id="cname">
<tr>
<td>${customer.cname }</td>
<td>${customer.gender }</td>
<td>${customer.birthday }</td>
<td>${customer.cellPhone }</td>
<td>${customer.email }</td>
<td>${customer.description }</td>
<td>
<a href="${pageContext.request.contextPath }/CustomerServlet?method=findCustomerById&cid=${customer.cid}">编辑</a>
<a href="javascript:_delete('${customer.cid }')">删除</a>
</td>
</tr>
</c:forEach>
</table>
<center style="font-size:2em;">
第${pageBean.cp }页/共${pageBean.tp }页
<a href="${pageContext.request.contextPath }/CustomerServlet?method=findAllCustomer&cp=1"/>首页</a>
<%--如果当前页为1 那么 不能够再上一页 --%>
<c:choose>
<c:when test="${pageBean.cp>1 }">
<a href="${pageContext.request.contextPath }/CustomerServlet?method=findAllCustomer&cp=${pageBean.cp-1}"/>上一页</a>
</c:when>
<c:otherwise>
上一页
</c:otherwise>
</c:choose>
<%-- 如果总页数小于10 那么第一个数字为1, 最后一个数字为总页数 --%>
<c:if test="${pageBean.tp<=10 }">
<c:set var="begin" value="1"/>
<c:set var="end" value="${pageBean.tp }"/>
</c:if>
<%--
如果总页数大于10, 那么第一个数字为cp-5, 最后一个数字为cp+4
--%>
<c:if test="${pageBean.tp>10 }">
<c:set var="begin" value="${pageBean.cp-5 }"/>
<c:set var="end" value="${pageBean.cp+4 }"/>
<c:if test="${begin<1 }">
<c:set var="begin" value="1"/>
<c:set var="end" value="10"/>
</c:if>
<c:if test="${end>pageBean.tp }">
<c:set var="begin" value="${pageBean.tp-9}"/>
<c:set var="end" value="${pageBean.tp }"/>
</c:if>
</c:if>
<c:forEach begin="${begin }" end="${end }" var="i">
<c:choose>
<c:when test="${pageBean.cp eq i }">
${i}
</c:when>
<c:otherwise>
<a href="${pageContext.request.contextPath }/CustomerServlet?method=findAllCustomer&cp=${i}">${i}</a>
</c:otherwise>
</c:choose>
</c:forEach>
<%-- 如果当前页等于总页数, 那么不能再下一页 --%>
<c:choose>
<c:when test="${pageBean.cp < pageBean.tp }">
<a href="${pageContext.request.contextPath }/CustomerServlet?method=findAllCustomer&cp=${pageBean.cp+1}"/>下一页</a>
</c:when>
<c:otherwise>
下一页
</c:otherwise>
</c:choose>
<a href="${pageContext.request.contextPath }/CustomerServlet?method=findAllCustomer&cp=${pageBean.tp}"/>尾页</a>
</center>
<script type="text/javascript">
function _delete(cid) {
var flag = window.confirm("确认要删除吗 ！！！");
if (flag == true) {
location.href = "${pageContext.request.contextPath}/CustomerServlet?method=deleteCustomerById&cid=" + cid;
}
}
</script>
</body>
</html>
结果演示:
演示.gif
完整代码地址(含SQL脚本)
https://github.com/menglanyingfei/Java/tree/master/JavaWebTrain/day_1_15/customer
