1，分页的原理：
通常我们从数据库取得的数据较多时不会全部展现出来，需要用到分页。
2，怎么取到我们所需要的数据呢？
*处理分页请求的Servlet或者jsp
*请求要显示页面的页码
*每页显示的信息数
*总页数
3，分页分为两大类：
*内存分页：一次将所有的页面查询出来，然后根据页面的请求显示指定的记录数。
*sql分页：根据页面的请求一次只从数据库中读取一页的结果，然后在页面显示该页。（select *from table limit 开始位置,结束位置）
下面开始进行分页实战：
1，首先我们创建一个page封装类，
1 package cn.com.yong.Pojo; 2 3 import java.util.List; 4 5 public class Page { 6 private int count;//总条数 7 private List<Announcement> evCount;//显示的数据 8 private int pageSize=6;//每页的条数 9 @SuppressWarnings("unused")10 private int pageCount;//总页数11 private int pageNow;//当前页12 public Page(){}13 public Page(int count, List<Announcement> evCount, int pageSize,14 int pageCount, int pageNow) {15 this.count = count;16 this.evCount = evCount;17 this.pageSize = pageSize;18 this.pageCount = pageCount;19 this.pageNow = pageNow;20 }21 public int getCount() {22 return count;23 }24 public void setCount(int count) {25 this.count = count;26 }27 public List<Announcement> getEvCount() {28 return evCount;29 }30 public void setEvCount(List<Announcement> evCount) {31 this.evCount = evCount;32 }33 public int getPageSize() {34 return pageSize;35 }36 37 public int getPageCount() {38 int i=0;39 if(getCount()%getPageSize()==0){40 i=getCount()/getPageSize();41 }else{42 i=getCount()/getPageSize()+1;43 }44 return i;45 }46 public void setPageCount(int pageCount) {47 this.pageCount = pageCount;48 }49 public int getPageNow() {50 return pageNow;51 }52 public void setPageNow(int pageNow) {53 this.pageNow = pageNow;54 }55 56 57 }2.我们写一个接口，加上我们需要实现的方法
1 public interface AnnouncementDao {2 3 public Page getListPage(Page page);4 5 }3.实现接口
1 public class AnnouncementDaoImplement implements AnnouncementDao{ 2 public Page getListPage(Page page) { 3 int coun=0;
//创建list对象，用来存储查询到的数据库数据 4 List<Announcement> list=new ArrayList<Announcement>();
//与数据库建立联系（通过单列设计模式实现，文章最后会附上） 5 con=DBConnection.getDBConnectionInstance().getDBConnection();
//查询总记录数 6 String sql="select count(*) from announcement";
//按照要求查询需要的记录 两个问号分别代表起始位置和结束位置 7 String sql2="select id,title,context from announcement limit ?,?"; 8 try { 9 ps=con.prepareStatement(sql2);
//下标从零开始，需要-110 ps.setInt(1, (page.getPageNow()-1)*page.getPageSize());11 ps.setInt(2, page.getPageSize());12 ResultSet rs2=ps.executeQuery();13 while(rs2.next()){14 Announcement an=new Announcement();15 an.setId(rs2.getInt(1));16 an.setTitle(rs2.getString(2));17 an.setContext(rs2.getString(3));
//把查询到的数据添加到list集合里18 list.add(an);19 }20 rs=con.createStatement().executeQuery(sql);21 if(rs.next()){22 coun=rs.getInt(1);23 24 }
//把得到的list集合设置给page的成员变量EvCount25 page.setEvCount(list);
//查询到的总记录数附给count26 page.setCount(coun);27 28 } catch (SQLException e) {29 e.printStackTrace();30 }31 return page;32 33 }34 35 }4，创建一个Servlet
import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import cn.com.yong.DaoImplement.AnnouncementDaoImplement;import cn.com.yong.Pojo.Page;@WebServlet("/AnnouncementFindAllServlet")public class AnnouncementFindAllServlet extends HttpServlet { private static final long serialVersionUID = 1L; Page page=null; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //创建一个session对象 HttpSession session=request.getSession();
//获取实现类中的参数page，得到里面的数据 page=(Page)session.getAttribute("page"); if(page==null){ page=new Page(); } int pageNow=0;
//获取当前页的属性 String str=request.getParameter("pageNow"); if(str==null){ pageNow=1; }else{ pageNow=Integer.parseInt(str); }
//把当前页得到的数值赋给page类中的pagenow变量 page.setPageNow(pageNow); AnnouncementDaoImplement adi=new AnnouncementDaoImplement(); //调用方法 page=adi.getListPage(page);
// 为page设置属性让jsp页面能够接受这个属性 session.setAttribute("page", page); response.sendRedirect("AnnouncementSelectAll.jsp"); }}5，jsp页面
1 <% 2 String path = request.getContextPath(); 3 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 4 Page pa=(Page)session.getAttribute("page"); 5 %> 6 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 8 <html> 9 <head> 10 <base href="<%=basePath%>"> 11 12 <title>My JSP 'AnnouncementDao.jsp' starting page</title> 13 14 <meta http-equiv="pragma" content="no-cache"> 15 <meta http-equiv="cache-control" content="no-cache"> 16 <meta http-equiv="expires" content="0"> 17 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 18 <meta http-equiv="description" content="This is my page"> 19 <script src='/images/loading.gif' data-original="jquery-1.6.4.min.js" type="text/javascript"></script> 20 <script type="text/javascript"> 21 $(document).ready(function demo(){ 22 23 $("th").css({ color: "black", background: "#DDDDDD" }); 24 25 26 }); 27 function getFirstPage(p){ 28 if(p==1){ 29 alert("你已经在首页了") 30 }else{ 31 window.location.href="AnnouncementFindAllServlet?pageNow=1"; 32 } 33 } 34 function getLastPage(p){ 35 var last=<%=pa.getPageCount()%>; 36 if(p==last){ 37 alert("你已经在尾页了"); 38 }else{ 39 window.location.href="AnnouncementFindAllServlet?pageNow="+last; 40 } 41 } 42 function getPageUp(p){ 43 if(p==1){ 44 alert("你已经在首页了"); 45 }else{ 46 window.location.href="AnnouncementFindAllServlet?pageNow="+(p-1); 47 } 48 } 49 function getPageDn(p){ 50 var last=<%=pa.getPageCount()%>; 51 if(p==last){ 52 alert("你已经在尾页了"); 53 }else{ 54 window.location.href="AnnouncementFindAllServlet?pageNow="+(p+1); 55 } 56 } 57 function getJumpPage(pn){ 58 var changePage = document.getElementById("jumpPage").value; 59 if(changePage ==-1){ 60 alert("请选择你要跳转的页面"); 61 }else if(changePage==pn){ 62 alert("您已经在该页"); 63 }else{ 64 window.location.href="AnnouncementFindAllServlet?pageNow="+changePage; 65 } 66 } 67 </script> 68 </head> 69 70 <body> 71 <p id="one" >公告管理</p> 72 <p >____________________________________________________________________________________________________</p> 73 <table align="center" width="100%" border="1" cellpadding="1" cellspacing="1" > 74 <tr> 75 <th>公告编号</th> 76 <th>公告标题</th> 77 <th>操作</th> 78 </tr> 79 <% 80 81 for(Announcement an:pa.getEvCount()){ 82 83 %> 84 85 86 <tr align="center"> 87 <td><%=an.getId()%></td> 88 <td><%=an.getTitle()%></td> 89 <td><a href="AnnouncementDelServlet?id=<%=an.getId()%>">删除</a>|| 90 <a href="AnnouncementUpdateServlet?id=<%=an.getId()%>">修改</a></td> 91 92 </tr> 93 94 <%} %> 95 </table> 96 <p>共<%=pa.getPageCount()%>页，当前第<%=pa.getPageNow()%>页 97 <span id="firstPage" onclick="getFirstPage(<%=pa.getPageNow()%>)">首页</span> 98 <span id="pageUp" onclick="getPageUp(<%=pa.getPageNow()%>)">上一页</span> 99 <span id="pageDn" onclick="getPageDn(<%=pa.getPageNow()%>)">下一页</span>100 <span id="lastPage" onclick="getLastPage(<%=pa.getPageNow()%>)">尾页</span>101 <span>102 <span>跳转到103 <select id="jumpPage" onchange="getJumpPage(<%=pa.getPageNow() %>)">104 <option value="-1">--请选择--</option>105 <%106 for(int i=1;i<=pa.getPageCount();i++){107 %>108 <option value="<%=i%>"><%=i%></option>109 <% }%>110 </select>111 页</span>112 </span>113 </p>114 </body>115 </html>附：jdbc单例
public class DBConnection { private String url="jdbc:mysql://localhost:3306/ei"; private String user="root"; private String password="666888"; private Connection con=null; //构造方法私有化 private DBConnection(){ try { Class.forName("com.mysql.jdbc.Driver"); con=DriverManager.getConnection(url, user, password); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } //创建一个私有化对象 private static DBConnection jdbc=new DBConnection(); //实例 public static DBConnection getDBConnectionInstance(){ return jdbc; } public Connection getDBConnection() { return con; }}
原标题：jsp分页
关键词：JS
我知道了 