JSP新闻系统之七 分页实现简化版

package com.news.util;

/**
 * 有了记录总条数后，页面控制类；
 * 根据总记录数，每页显示条数，来得到总页数;
 * @author Administrator
 *
 */
public class PageControler {
	public int getTotalPages(int count,int pageSize){
		int totalPages=0;
		//如果总记录数除以每页显示条数，能够整除;
		//总页数就是它们的商，否则为商+1
		if(count%pageSize==0){
			totalPages=count/pageSize;
		}else{
			totalPages=count/pageSize+1;
		}
		return totalPages;
	}
}

  

   

    

     

    
    

     

      UserDao中的抽象方法
     
    
   

    

     

    
    

     

      //通过查询获取数据表中数据总条数;
     
    
   

    

     

    
    

     
	public int getCount();
     
    
   

    

     

    
    

     
	//根据当前页码和页数，来分页的方法;返回User集合;
     
    
   

    

     

    
    

     
	public List<User>queryUserByPage(int currentPage,int pageSize);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      //UserDaoImpl实现类中的方法
     
    
   

    

     

    
    

     

      /* 获得user的总个数,即要分页的总记录数
     
    
   

    

     

    
    

     

       * @see com.news.dao.UserDao#getCount()
     
    
   

    

     

    
    

     

       */
     
    
   

    

     

    
    

     
	@Override
     
    
   

    

     

    
    

     
	public int getCount() {
     
    
   

    

     

    
    

     

      		Connection con=null;
     
    
   

    

     

    
    

     

      		Statement st=null;
     
    
   

    

     

    
    

     

      		ResultSet rs=null;
     
    
   

    

     

    
    

     
		int count=0;
     
    
   

    

     

    
    

     
		
     
    
   

    

     

    
    

     
		try {
     
    
   

    

     

    
    

     

      			con=DaoFactory.getConnection();
     
    
   

    

     

    
    

     

      			st=con.createStatement();
     
    
   

    

     

    
    

     

      			String sql="select count(*) from t_user";
     
    
   

    

     

    
    

     

      			rs=st.executeQuery(sql);
     
    
   

    

     

    
    

     
			if(rs.next()){
     
    
   

    

     

    
    

     

      				count=rs.getInt(1);
     
    
   

    

     

    
    

     

      			}
     
    
   

    

     

    
    

     

      		} catch (SQLException e) {
     
    
   

    

     

    
    

     

      			e.printStackTrace();
     
    
   

    

     

    
    

     

      		}finally{
     
    
   

    

     

    
    

     

      			DaoFactory.closeAll(rs, st, con);
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     
		return count;
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	@Override
     
    
   

    

     

    
    

     
	public List<User> queryUserByPage(int currentPage, int pageSize) {
     
    
   

    

     

    
    

     

      		Connection con=null;
     
    
   

    

     

    
    

     

      		Statement st=null;
     
    
   

    

     

    
    

     

      		ResultSet rs=null;
     
    
   

    

     

    
    

     

      		List<User>users=null;
     
    
   

    

     

    
    

     
		
     
    
   

    

     

    
    

     
		try {
     
    
   

    

     

    
    

     

      			con=DaoFactory.getConnection();
     
    
   

    

     

    
    

     

      			st=con.createStatement();
     
    
   

    

     

    
    

     

      			users=new ArrayList<User>();
     
    
   

    

     

    
    

     

      			String sql="select top "+pageSize+" * from t_user where id not in (select top "+(currentPage-1)*pageSize+" id from t_user order by id)order by id";
     
    
   

    

     

    
    

     

      			rs=st.executeQuery(sql);
     
    
   

    

     

    
    

     
			//遍历结果集
     
    
   

    

     

    
    

     
			while(rs.next()){
     
    
   

    

     

    
    

     
				//从数据库中取出一条记录后，放到实体对象中;
     
    
   

    

     

    
    

     

      				User user=new User();
     
    
   

    

     

    
    

     

      				user.setId(rs.getInt("id"));
     
    
   

    

     

    
    

     

      				user.setUsername(rs.getString("username"));
     
    
   

    

     

    
    

     

      				user.setEmail(rs.getString("email"));
     
    
   

    

     

    
    

     

      				user.setAddress(rs.getString("address"));
     
    
   

    

     

    
    

     

      				user.setHobby(rs.getString("hobby"));
     
    
   

    

     

    
    

     
				//将实体对象放入集合中;
     
    
   

    

     

    
    

     

      				users.add(user);
     
    
   

    

     

    
    

     

      			}
     
    
   

    

     

    
    

     

      		} catch (SQLException e) {
     
    
   

    

     

    
    

     

      			e.printStackTrace();
     
    
   

    

     

    
    

     

      		}finally{
     
    
   

    

     

    
    

     

      			DaoFactory.closeAll(rs, st, con);
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     
		return users;
     
    
   

    

     

    
    

     

      	}
     
    
  
 

show_user.jsp页面代码如下

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page import="com.news.dao.*,com.news.dao.impl.*,com.news.entity.*,com.news.util.*" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.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="css/css.css">
  </head>
  
  <body>
  <table border="1" align="center">
  	<caption>=用户列表</caption>
  	<tr>
  		<td>编号</td>
  		<td>账号</td>
  		<td>密码</td>
  		<td>邮箱</td>
  		<td>住址</td>
  		<td>爱好</td>
  	</tr>
  	<%
   		//获取当前页码，如果获取不到，默认是第一页;
   		String pageIndex=request.getParameter("pageIndex");
   		if(pageIndex==null){
   			pageIndex="1";
   		}
   		int currentPage=Integer.parseInt(pageIndex);
   		int pageSize=4;
   		UserDao ud=new UserDaoImpl();
   		PageControler pc=new PageControler();
   		int count=ud.getCount();
   		//获得总页数;
   		int totalPages=pc.getTotalPages(count,pageSize);
   		//分页查询，得到当前页数数据;
   		List<User>users=ud.queryUserByPage(currentPage,pageSize);
   		for(int i=0;i<users.size();i++){
   			User user=users.get(i);
    %>
  	<tr>
  		<td><%=user.getId() %></td>
  		<td><%=user.getUsername() %></td>
  		<td><%=user.getPwd() %></td>
  		<td><%=user.getEmail() %></td>
  		<td><%=user.getAddress() %></td>
  		<td><%=user.getHobby() %></td>
  	</tr>
  	<%
  		}
  	 %>
  	 <!-- 分页控制 -->
  	 <tr class="altrow">
  	 	<td colspan="6">
  	 		第<%=currentPage %>页/共<%=totalPages %>页
  	 		<a href='admin/show_user.jsp?pageIndex=<%=1 %>'>首页</a>
  	 		<% 
  	 			if(currentPage>1){
  	 		 %>
  	 		 <a href='admin/show_user.jsp?pageIndex=<%=currentPage-1 %>'>上一页||</a>
  	 		 <%
  	 		 	}
  	 		 	if(currentPage<totalPages){
  	 		  %>
  	 		  <a href='admin/show_user.jsp?pageIndex=<%=currentPage+1 %>'>下一页</a>||
  	 		  <%} %>
  	 		  <a href='admin/show_user.jsp?pageIndex=<%=totalPages %>'>末页</a>
  	 	</td>
  	 </tr>
  	</table>   
  </body>
</html>

文章来源: aaaedu.blog.csdn.net，作者：tea_year，版权归原作者所有，如需转载，请联系作者。

原文链接：aaaedu.blog.csdn.net/article/details/53086404