分页-代码实现

共计 6505 个字符，预计需要花费 17 分钟才能阅读完成。

分页 - 代码实现

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);
		}
	}
}