分页

package isa.controller;

import isa.model.DeptBean;
import isa.model.DeptBeanCl;

import java.io.IOException;
import java.util.HashMap;

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

public class DeptSAServlet extends HttpServlet {

 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  this.doPost(request, response);
 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
//  希望得到用户的pageNow
  String p=request.getParameter("pageNow");
  System.out.println("a");
//  创建DeptBeanCl方法
  DeptBeanCl dbc=new DeptBeanCl();
  System.out.println("b");
//  在跳转到xhshow.jsp页面时，就把要显示的数据给Welcome准备好
  HashMap<String,DeptBean> hm=dbc.getDepts();
  System.out.println("c");
//  将al,pageCount放入request中
  request.setAttribute("result", hm);
  request.setAttribute("pageNow", p);
  System.out.println("d");
//  转发,效率高，request中的对象还可以在下一页面中使用
  request.getRequestDispatcher("xhshow.jsp").forward(request, response);
 }

}
<%@ page language="java" import="java.util.*,isa.model.DeptBean" contentType="text/html;charset=gb2312" pageEncoding="gb2312"%>
<html>
  <head>
    <base href="<%=basePath%>">
   
    <title></title>
<script language="javascript">
function fsubmit(obj){
 obj.submit();
}
function freset(obj){
 obj.reset();
}
</script>
  </head>
 
  <body  bgcolor="#ccffff">
  <%
  int pageSize=5;
  //要显示的信息从Request中取
  System.out.println(pageSize);
  HashMap<String,DeptBean> hm=(HashMap<String,DeptBean>)request.getAttribute("result");
  int size=hm.size();
  System.out.println(size);
  //接收用户希望显示的页数（pageNow）
  String s_pageNow=(String)request.getAttribute("pageNow");
  System.out.println(s_pageNow);
  int pageNow=Integer.parseInt(s_pageNow);
  System.out.println(pageNow);
  int pageCount=(int)(size+4)/pageSize;
  System.out.println(pageCount);
 %>
 <table width="750" height="250" align="center" cellpadding="0" cellspacing="0" border="1">
   <tr >
     <td  align="center" valign="middle">部门号</td><td valign="middle" align="center">部门名</td><td align="center" valign="middle">部门人数</td><td align="center" valign="middle">负责人</td><td align="center" valign="middle">副负责人</td><td align="center" valign="middle">联系电话</td>
   </tr>
   <%
   for(int i=(pageNow-1)*pageSize+1;i<pageNow*pageSize+1;i++){
    if (hm.containsKey(i+"")) {
    DeptBean db=(DeptBean)hm.get(i+"");
   %>
   <tr>
     <td align="center" valign="middle"><%=db.getdNo() %></td><td align="center" valign="middle"><%=db.getdName() %></td><td align="center" valign="middle"><%=db.getdNum() %></td><td align="center" valign="middle"><%=db.getdMinister() %></td><td align="center" valign="middle"><%=db.getdVice() %></td><td align="center" valign="middle"><%=db.getdTel() %></td>
   </tr>
   <%} }%>
    <tr>
    <td colspan="<%=6 %>" scope="row" align="center" valign="bottom">
  <table align="center" border="0">
     
    <tr>
         <td width="*"></td>
      <%
       if(pageNow!=1){
    %>
         <td align="center" valign="middle">
          <form id="form1" name="form1" method="post" action="DeptSAServlet">
        <input type="hidden" name="pageNow" value="<%=(pageNow-1) %>" />
                  <a href="javascript:fsubmit(document.form1);">
                  <img border="0"  src="imgs/pre.jpg" name="picture1"
          onmouseover="picture1.src='imgs/pre1.jpg'"onmouseout="picture1.src='imgs/pre.jpg'"></a>
         </form>
         </td>
    <%
    //     out.println("<a href=DeptSBServlet?pageNow="+(pageNow-1)+">上一页</a>");
      
        }
       for(int i=0;i<pageCount;i++){
       %>
         <td align="center" valign="middle">
         
         </td>
    <%
   //      out.println("<a href=DeptSBServlet?pageNow="+i+">["+i+"]</a>");
       }
       if(pageNow!=pageCount){
       %>
         <td align="center" valign="middle">
          <form id="form2" name="form2" method="post" action="DeptSAServlet">
        <input type="hidden" name="pageNow" value="<%=(pageNow+1) %>" />
                  <a href="javascript:fsubmit(document.form2);">
                  <img border="0"  src="imgs/next.jpg" name="picture2"
          onmouseover="picture2.src='imgs/next1.jpg'"onmouseout="picture2.src='imgs/next.jpg'"></a>
         </form>
         </td>
    <%
   //       out.println("<a href=DeptSBServlet?pageNow="+(pageNow+1)+">下一页</a>");
       }
       %>
       <td width="*"></td>
     </tr>
    </table>
 </td>
 </tr>

</table>
</body>

</html>
package isa.model;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.HashMap;

public class DeptBeanCl {
 private Connection ct=null;
 private PreparedStatement ps=null;
 private ResultSet rs=null;
// private int pageSize=3;
// private int rowCount=0;//该值从数据库中查询
// private int pageCount=0;//该值是通过pageSize和rpwCount
////  关闭资源
 public void close(){
  try{
   if(rs!=null) {
    rs.close();
    rs=null;
   }
   if(ps!=null) {
    ps.close();
    ps=null;
   }
   if(ct!=null) {
    ct.close();
    ct=null;
   }
  }catch(Exception e){
   e.printStackTrace();
  }
 }
////  返回分页的总页数
// public int getpageCount(){
//  System.out.println("H");
//  try{
//   ct=(new ConnDB()).getConn();
//   //得到链接
//   System.out.println("I");
//   ps=ct.prepareStatement("select count(*) from dept");
//   System.out.println("J");
//     rs=ps.executeQuery();
//     System.out.println("K");
//     if(rs.next()){
//      System.out.println("L");
//      rowCount=rs.getInt(1);
//     }
//     System.out.println(rowCount);
//     pageCount=(int)(rowCount+2)/pageSize;
//  }catch(Exception e){
//   e.printStackTrace();
//  }finally{
//   this.close();
//  }
//  return pageCount;
// }
//  得到用户需要显示的用户信息(分页)
 public HashMap<String,DeptBean> getDepts(){
  HashMap<String,DeptBean> hm=new HashMap<String,DeptBean>();
  System.out.println("A");
  try{
   int n=1;
//   到数据库去验证
   ct=(new ConnDB()).getConn();
   ps=ct.prepareStatement("select dNo,dName,dNum,dMinister,dVice,dTel from dept");
     System.out.println("D");
   rs=ps.executeQuery();
     System.out.println("E");
     while(rs.next()){
      System.out.println("F");
      DeptBean db=new DeptBean();
      db.setdNo(rs.getString(1));
      db.setdName(rs.getString(2));
      db.setdNum(rs.getInt(3));
      db.setdMinister(rs.getString(4));
      db.setdVice(rs.getString(5));
      db.setdTel(rs.getString(6));
      hm.put(n+"", db);
      n=n+1;
      System.out.println("G");
     }
  }catch(Exception e){
   System.out.println("WW");
   e.printStackTrace();
  }finally{
   this.close();
  }
  return hm;
 }
 public String getdNo(String n){
  String no=null;
  try{
//   到数据库去验证用户
   ct=(new ConnDB()).getConn();
   ps=ct.prepareStatement("select dNo from dept where dName=?");
   ps.setString(1, n);
   rs=ps.executeQuery();
     while(rs.next()){
      no=rs.getString(1);
      break;
     }
  }catch(Exception e){
   e.printStackTrace();
  }finally{
   this.close();
  }
  System.out.println(no);
  return no;
 }
 public boolean decreaseNum(String d){
  boolean b=true;
  try{
//   到数据库去验证用户
   ct=(new ConnDB()).getConn();
   ps=ct.prepareStatement("update dept set dNum=dNum-1 where dNo=?");
   ps.setString(1, d);
   ps.executeUpdate();
  }catch(Exception e){
   b=false;
   e.printStackTrace();
  }finally{
   this.close();
  }
  return b;
 }
 public boolean addNum(String d){
  boolean b=true;
  try{
//   到数据库去验证用户
   ct=(new ConnDB()).getConn();
   ps=ct.prepareStatement("update dept set dNum=dNum+1 where dName=?");
   ps.setString(1, d);
   ps.executeUpdate();
  }catch(Exception e){
   b=false;
   e.printStackTrace();
  }finally{
   this.close();
  }
  return b;
 }
}
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原文地址：https://www.cnblogs.com/mingforyou/p/2200041.html