java中的分页（最基础的方法）

/**
* 有关该方法的简介
* PageModel 类，分页的实体类
* UtilDB 类，数据库的关闭与连接
* StudentDao 类，执行分页查询的类
* Fenye02-1 类，servlet处理类
* fenye02-1.jsp ，显示结果的页面
*
* 注：该分页方法连接的数据库是Oracle数据库，如果要连接sqlserver数据库，则改变连接的方式即可，其他的都一样
*
*/

//PageModel 类

import java.util.List;

public class PageModel<T> {

// 定义当前页
private int pageNo;
// 每页显示的记录数
private int pageSize;
// 总记录数
private int count;
// 数据集合
private List<T> all;

public List<T> getAll() {
return all;
}

public void setAll(List<T> all) {
this.all = all;
}

/**
* 首页
*
* @return
*/
public int getIndex() {
return 1;
}

/**
* 尾页
*
* @return
*/
public int getLastPage() {
if (this.getCount() % this.getPageSize() == 0) {
return this.getCount() / this.getPageSize();
} else {
return this.getCount() / this.getPageSize() + 1;
}
}

/**
* 上一页
*
* @return
*/
public int getPagePerv() {
if (this.getPageNo() - 1 < 1) {
return 1;
} else {
return this.getPageNo() - 1;
}
}

/**
* 下一页
*
* @return
*/
public int getPageNext() {
if (this.getPageNo() + 1 > this.getLastPage()) {
return this.getLastPage();
} else {
return this.getPageNo() + 1;
}
}

/**
* 各属性的 get/set 方法
*
* @return
*/
public int getPageNo() {
return pageNo;
}

public void setPageNo(int pageNo) {
this.pageNo = pageNo;
}

public int getPageSize() {
return pageSize;
}

public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}

public int getCount() {
return count;
}

public void setCount(int count) {
this.count = count;
}
}

//UtilDB 类

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UtilDB {
/**
* 得到数据库操作对象
*/
private static Connection con=null;

/**
* 链接数据库
* @return
*/
public static Connection getCon(){
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "tiger");
} catch (Exception e) {
e.printStackTrace();
}
return con;
}

/**
* 关闭数据库
* @param pst
* @param rs
* @param con
* @throws SQLException
*/
public static void closeDB(PreparedStatement pst,ResultSet rs,Connection con) throws SQLException{
if(pst!=null){
pst.close();
}
if(rs!=null){
rs.close();
}
if(con!=null){
con.close();
}
}
}

//StudentDao 类

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import util.UtilDB;

import entity.PageModel;
import entity.StudentInfo;

public class StudentDao {
/**
* 得到数据库操作对象
*/

private static PreparedStatement pst=null;
private static ResultSet rs=null;
private static Connection con=null;

public PageModel<StudentInfo> selectAll(int pageNo,int pageSize){
//创建 pagemodel 对象
PageModel<StudentInfo> pm=new PageModel<StudentInfo>();
//创建集合，用于封装  student 信息
List<StudentInfo> slist=new ArrayList<StudentInfo>();

try {
//链接数据库
con=UtilDB.getCon();
pst=con.prepareStatement("select * from (select rownum r ,s.* from studentinfo s) where r between ("+pageNo+"-1)*10+1 and "+pageNo+"*"+pageSize+"");
//执行 sql 语句
rs=pst.executeQuery();
while(rs.next()){
//下标从 2 开始，因为 下标为 1 的是 rownum,如果从1开始会报错
StudentInfo s=new StudentInfo(rs.getInt(2), rs.getString(3), rs.getString(4), rs.getInt(5));
slist.add(s);
}
//为  pagemodel 类设置值
pm.setAll(slist);
pm.setPageNo(pageNo);
pm.setPageSize(pageSize);
pm.setCount(this.count());
} catch (Exception e) {
e.printStackTrace();
}finally{
try {
//关闭数据库
UtilDB.closeDB(pst, rs, con);
} catch (Exception e) {
e.printStackTrace();
}
}
return pm;
}

/**
* 得到总共有多少条数据
* @return
*/
public int count(){
int count=0;
try {
//链接数据库
con=UtilDB.getCon();
pst=con.prepareStatement("select count(*) from  studentinfo");
//执行sql
rs=pst.executeQuery();
if(rs.next()){
count=rs.getInt(1);
}

} catch (Exception e) {
e.printStackTrace();
}finally{
try {
//关闭数据库
UtilDB.closeDB(pst, rs, con);
} catch (SQLException e) {
e.printStackTrace();
}
}
return count;
}
}

//通过一个超链接跳转到该servlet处理类来

//Fenye02-1 servlet类

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.StudentDao;
import entity.PageModel;
import entity.StudentInfo;

public class Fenye02_1 extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//最好调用doPost方法
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获取页面传过来的当前页的页码（pageNo）
String str=request.getParameter("pageNo");
StudentDao dao=new StudentDao();
//当前页
int pageNo=1;
//每页显示的条数
int pageSize=10;
//第一次到该servlet时,pageNo为null,所以比较pageNo是否为null,如果不为null,则改变当前页的页码
if(str!=null&&!"".equals(str)){
pageNo=Integer.parseInt(str);
}
//调用分页查询的方法
PageModel<StudentInfo> pm=dao.selectAll(pageNo, pageSize);
//将查询的结果保存到请求中
request.setAttribute("pm", pm);
//跳转
request.getRequestDispatcher("../fenye02_1.jsp").forward(request, response);
}

}

//fenye02-1.jsp 页面的主要代码

<%
PageModel<StudentInfo> pm=(PageModel<StudentInfo>)request.getAttribute("pm");
%>
</head>

<body>
<hr/>
<table border="1" cellpadding="0" cellspacing="0" align="center" width="60%" height="">

<tr align="center">
<td>学号</td>
<td>姓名</td>
<td>性别</td>
<td>年龄</td>
</tr>
<%
for(StudentInfo s:pm.getAll()){
%>
<tr align="center">
<td><%=s.getStuNo() %></td>
<td><%=s.getName() %></td>
<td><%=s.getSex() %></td>
<td><%=s.getAge() %></td>
</tr>
<%

}
%>
<tr>
<td colspan="4" align="center">
<a href="servlet/Fenye02_1?pageNo=1">首页</a> 
<a href="servlet/Fenye02_1?pageNo=<%=pm.getPagePerv() %>">上一页</a> 
<a href="servlet/Fenye02_1?pageNo=<%=pm.getPageNext() %>">下一页</a> 
<a href="servlet/Fenye02_1?pageNo=${pm.lastPage}">尾页</a> 
</td>
</tr>
</table>
</body>