分页-代码实现
1、分页数据流转流程图
image20200504104541892.png
PageBean.java
import java.util.List;
public class PageBean<T> {
private List<T> beanList;// 当前页记录数, 需要传递
private int tr;// 总记录数, 需要传递
private int pc;// 当前页码, 需要传递
private int ps;// 每页记录数, 需要传递
private int tp;// 总页数, 计算
//其他的提供get/set方法
//但tp只提供get方法
public int getTp(){
tp=tr/ps;
return tr%ps==0?tp:tp+1;
}
public List<T> getBeanList() {
return beanList;
}
public void setBeanList(List<T> beanList) {
this.beanList = beanList;
}
public int getTr() {
return tr;
}
public void setTr(int tr) {
this.tr = tr;
}
public int getPc() {
return pc;
}
public void setPc(int pc) {
this.pc = pc;
}
public int getPs() {
return ps;
}
public void setPs(int ps) {
this.ps = ps;
}
}index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<jsp:forward page="/frame.jsp" />frame.jsp
<%@ 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>主页</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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<frameset rows="20%,*">
<frame src="<c:url value='/top.jsp'/>" name="top"/>
<frame src="<c:url value='/welcome.jsp'/>" name="main"/>
</frameset>
</html>top.jsp
<%@ 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>
<!-- 它的作用是为本页面所有的表单和超链接指定显示内容的框架！ -->
<base target="main">
<title>My JSP 'top.jsp' starting page</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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body style="text-align: center;">
<a href="<c:url value='/CustomerServlet'/>">查询客户</a>
</body>
</html>welcome.jsp
<%@ 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>My JSP 'welcome.jsp' starting page</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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<h1 align="center">欢迎登录本系统</h1>
</body>
</html>list.jsp
<%@ 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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</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 items="${pb.beanList}" var="cstm">
<tr>
<td>${cstm.cname }</td>
<td>${cstm.gender }</td>
<td>${cstm.birthday }</td>
<td>${cstm.cellphone }</td>
<td>${cstm.email }</td>
<td>${cstm.description }</td>
<td>
<a href="#">编辑</a>
<a href="#">删除</a>
</td>
</tr>
</c:forEach>
</table>
</br>
<!-- 给出分页相关的链接 -->
<center>
<a href='<c:url value="/CustomerServlet" />'>首页</a>
<a href='<c:url value="/CustomerServlet?pc=${pb.pc-1 }" />'>上一页</a>
<a href='<c:url value="/CustomerServlet?pc=${pb.pc+1 }" />'>下一页</a>
<a href='<c:url value="/CustomerServlet?pc=${pb.tp}" />'>尾页</a>
</center>
</body>
</html>CustomerServlet.java
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class CustomerServlet
*/
public class CustomerServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
CustomerDao customerDao = new CustomerDao();
/**
* @see HttpServlet#HttpServlet()
*/
public CustomerServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/*
* 1、获取页面传递的pc
* 2、给定ps的值
* 3、使用pc和ps调用service方法，得到PageBean,保存到request域
* 4、转发到list.jsp
* */
/*
* 1.得到pc
* 如果pc参数不存在，说明pc=1
* 如果pc参数存在，需要转换成int类型即可
* */
int pc = getPc(request);
int ps = 10;
PageBean pb = customerDao.findAll(pc,ps);
request.setAttribute("pb", pb);
request.getRequestDispatcher("/list.jsp").forward(request, response);
}
public int getPc(HttpServletRequest request) {
String value = request.getParameter("pc");
if(value==null || value.trim().isEmpty()) {
return 1;
}
return Integer.parseInt(value);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}CustomerDao.java
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class CustomerDao {
private QueryRunner qr = new QueryRunner(new ComboPooledDataSource());
/**
* 添加客户
*
* @param c
*/
public void add(Customer c) {
try {
String sql = "insert into t_customer values(?,?,?,?,?,?,?)";
Object[] params = { c.getCid(), c.getCname(), c.getGender(),
c.getBirthday(), c.getCellphone(), c.getEmail(),
c.getDescription()};
qr.update(sql, params);
} catch(SQLException e) {
throw new RuntimeException(e);
}
}
public PageBean findAll(int pc,int ps) {
try {
/*
* 创建PageBean对象pb
* 设置pb的pc和ps
* 得到tr,给pb设置tr
* 得到beanList，设置给pb
* */
PageBean<Customer> pb = new PageBean<Customer>();
pb.setPc(pc);
pb.setPs(ps);
/*
* 得到tr
* */
String sql = "select count(*) from t_customer";
Number num = (Number)qr.query(sql, new ScalarHandler());
int tr = num.intValue();
pb.setTr(tr);
/*
* 得到beanList
* */
sql = "select * from t_customer limit ?,?";
List<Customer> beanList = qr.query(sql,
new BeanListHandler<Customer>(Customer.class),
(pc-1)*pb.getPs(),
pb.getPs());
pb.setBeanList(beanList);
return pb;
} catch(SQLException e) {
throw new RuntimeException(e);
}
}
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