MVC模式-数据库分页技术

今天编了一个MVC模式数据库分页的程序拿出来和大家分享一下!!

以下程序是在tomcat5.5,SQL server2000,servlet2.4,jsp2.0 中调试的

1.在SQL中建立数据库,字段(标题，主题，日期)

相信大家对数据库的建立应该是再熟悉不过了

2.先建个数据库连接的类:

package database;

import java.sql.*;

public class DataConn {
Connection con;
public DataConn()
{

}
public Connection getCon()   //返回Connection连接的方法
{
  try
  {
   Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
   con = DriverManager.getConnection("jdbc:odbc:Driver={SQL Server};server=.;database=myhome","","");
   return con;
  }
  catch(Exception ex)
  {
   System.out.println(ex.getMessage());
  }
  return null;
}

}

3.再建立个用于分页的javaBean:

package database;

import java.sql.*;
import java.util.*;

public class UseBean {
private int curtpage=1; //当前页
private int allpage; //一供多少页
public int rowspage=5; //一页多少记录
private int allrows; //共多少记录
public Vector data;
public UseBean () throws Exception
{
this.setBean(); //在这初始化一下是为了在JSP页面中一开始就能得到数据库中的记录

}
public int getCurtpage()
{
  return curtpage;
}
public void setCurtpage(int curtpage)
{
  this.curtpage=curtpage;
}
public int getAllpage()
{
  return allpage;
}
public void setAllpage(int allpage)
{
  this.allpage=allpage;
}
public int getAllrows()
{
  return allrows;
}
public void setAllrows(int allrows)
{
  this.allrows=allrows;
}

public int getallpages() throws Exception
{
  //求出一共多少页
  String sql = "select * from article";
  DataConn con = new DataConn();
  Connection conn= con.getCon();
     Statement stmt = conn.createStatement();
     ResultSet st = stmt.executeQuery(sql);
     int i=0;
     while(st.next())
     {
     i++;
     }
     return i;
}
public UseBean getResultpage(String page) throws Exception //得到要显示的那一页的记录
{
  UseBean ub= new UseBean();
  int pagenum = Integer.parseInt(page);
  String sql="select top "+pagenum*ub.rowspage+" * from article"; //得到是要显示在本页的及以前的数据记录之各

  Vector v = new Vector();     // 定义一个数据集
  DataConn con =new DataConn();
  Connection conn = con.getCon();
  Statement stmt = conn.createStatement();
  ResultSet rs = stmt.executeQuery(sql);
  int i=0;
  while(rs.next())
  {
   if(i>(pagenum-1)*ub.rowspage-1)      //控制只把本页的数据赋到object对象中
   {
   Object[] object = new Object [3];
   object [0] = rs.getString(1);
   object [1] = rs.getString(2);
   object [2] = rs.getString(3);
   v.add(object);
   }
   i++;
  }
  rs.close();
  stmt.close();
  ub.setCurtpage(pagenum);     //设置当前为第几页
  ub.data=v;                          //把数据集V赋给数据集data
  return ub;
}

public void setBean() throws Exception //设置总行数和设置总业数
{
  this.setAllrows(this.getallpages());    //设置总行数
  if(this.allrows%this.rowspage==0)
  {
   this.allpage = this.allrows/this.rowspage; //设置总页数:正好是整数倍的
  }
  else
  {
   this.allpage=this.allrows/this.rowspage+1; //设置总页数: 不是整数倍的
  }

}

}

4.建立用于分页的JSP界面:

<%@ page language="java" contentType="text/html; charset=GBK"
    pageEncoding="GBK"%>
<jsp:useBean id="page2" class="database.UseBean" scope="request" />
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>Insert title here</title>
<script language="javascript" >
function Jumping()
{
   document.form1.submit();
   return ;
}
function gotopage(pagenum)
{
   document.form1.JumpPage.value=pagenum;
   document.form1.submit();
   return;
}
</script>
</head>
<body>
<table align="center" border="1">
<tr>
<td>主题</td>
<td>作者</td>
<td>日期</td>
</tr>
<%
   String s =String.valueOf(page2.getCurtpage());
   java.util.Vector v=page2.getResultpage(s).data;
   java.util.Enumeration e =v.elements(); //elements把集合转换成枚举并赋给枚举e; Enumeration定义枚举
   while(e.hasMoreElements())
   {
    Object [] object =(Object[]) e.nextElement();
%>

<%}%>
<%
if(page2.getCurtpage()==page2.getAllpage())
{
out.println("下一页尾页 ");
}
else
{
%>
<a href="javascript:gotopage(<%=page2.getCurtpage()+1 %>)">下一页</a>
<a href="javascript:gotopage(<%=page2.getAllpage() %>)">尾页</a>

<%} %>
<select name="JumpPage" onchange="Jumping()">
<%
for(int i=1;i<=page2.getAllpage();i++)
{
   if(page2.getCurtpage()==i)
   {
%>
<option selected=<%=i %>><%=i %> </option>
<%}
   else
   {
   %>
<option value=<%=i %>><%=i %> </option>
<%
   }
}
%>
</select>
</p>
</form>
</body>
</html>

5.最后是建立servlet了:

package database;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/**
* Servlet implementation class for Servlet: Pageservlet
*
*/
public class Pageservlet extends HttpServlet {
    /* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#HttpServlet()
*/
public Pageservlet() {
  super();
}

/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
     response.setContentType( "text/html; charset=GBK");
     response.setCharacterEncoding("GBK");
  PrintWriter p = response.getWriter();

  try
  {
  String page = request.getParameter("JumpPage");
  UseBean page1 = new UseBean();
  UseBean page2 = page1.getResultpage(page);
  request.setAttribute("page2", page2);
  }
  catch(Exception ex)
  {
   ex.printStackTrace();
  }
  javax.servlet.RequestDispatcher dis=request.getRequestDispatcher("pageview.jsp");   //跳转到pageview.jsp页
       dis.forward(request,response);

}

/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request,response);
}
}