javabean servlet jsp实现分页功能代码解析

前端实现用ligerUI实现分页，感觉用框架确实简单，闲着无聊，模拟着liger的分页界面实现了一遍（只要是功能，样式什么无视） 

这里用基础的三层架构+servlet+jsp实现，思路很简单，把所有分页相关信息写入到一个pagebean类里面，service返回这个bean类，每次分页查询时都从该bean里查找信息。只是其中的细节问题比较繁琐，如边界处理（前端和后台边界都要处理），下拉框跳转后要显示当前页等等 

这是ligerUI实现的分页样式 

模拟实现过程： 

目录结构

数据库（mysql）

model层,一个数据库对应的model（Blog），还有一个pageBean(BlogPage) 

import java.sql.Date;

public class Blog {
private int id;
private int category_id;
private String title;
private String content;
private Date created_time;
//getter和setter方法
@Override
public String toString() {
 return "Blog [id=" + id + ", category_id=" + category_id + ", title=" + title + ", content=" + content
   + ", created_time=" + created_time + "]";
}
}

public class BlogPage {
private List<Blog> pagerecord;//每页记录
private int pageno;//当前页
private int pagenostart;//每页开始索引
private int pagesize=5;//每页多少数据
private int totalrecord;//总记录数
private int totalpage;//总页数

public BlogPage(int pageno,int totalrecord){
 //pageno totalrecord都可以当做已有信息
 this.totalrecord=totalrecord;
 //计算总页数
 totalpage=(totalrecord％pagesize==0)?totalrecord/pagesize:totalrecord/pagesize+1;
 //pageno的边界处理
 if(pageno<=1)
  this.pageno=1;
 else if(pageno>=totalpage)
  this.pageno=totalpage;
 else
  this.pageno=pageno;
 //计算每页开始索引，即每页第一个数据的索引，用于分页查询
 pagenostart=(this.pageno-1)*pagesize;
}
public int getPagenostart() {
 return pagenostart;
}
public void setPagenostart(int pagenostart) {
 this.pagenostart = pagenostart;
}
public List<Blog> getPagerecord() {
 return pagerecord;
}
public void setPagerecord(List<Blog> pagerecord) {
 this.pagerecord = pagerecord;
}
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 getTotalrecord() {
 return totalrecord;
}
public void setTotalrecord(int totalrecord) {
 this.totalrecord = totalrecord;
}
public int getTotalpage() {
 return totalpage;
}
public void setTotalpage(int totalpage) {
 this.totalpage = totalpage;
}
}


 

dao层

JDBCUtil封装了jdbc的连接和释放操作

public class JDBCUtil {
private static String url = "jdbc:mysql://localhost:3306/blogs_stu";
private static String username = "root";
private static String password = "";
static {
 try {
  Class.forName("com.mysql.jdbc.Driver");
 } catch (Exception e) {
  e.printStackTrace();
 }
}
public static Connection getConnection(){
 Connection conn;
 try {
  conn= DriverManager.getConnection(url, username, password);
  return conn;
 } catch (SQLException e) {
  e.printStackTrace();

}
 return null;
}
public static void release(ResultSet rs,PreparedStatement ps,Connection conn){
 if(rs!=null){
  try {
   rs.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
 if(ps!=null){
  try {
   ps.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
 if(conn!=null){
  try {
   conn.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
}
}

public class BlogDao {
//每页的记录，传入每页开始索引和每页大小用于分页，即limit的两个参数（mysql分页用limit）
public List<Blog> getPageRecord(int pagenostart, int pagesize) {
 Connection conn = JDBCUtil.getConnection();
 PreparedStatement ps = null;
 ResultSet rs = null;
 String sql = "select * from blog limit ?,?";
 List<Blog> list = new ArrayList<Blog>();
 try {
  ps = conn.prepareStatement(sql);
  ps.setInt(1, pagenostart);
  ps.setInt(2, pagesize);
  rs = ps.executeQuery();
  while (rs.next()) {
   Blog blog = new Blog();
   blog.setId(rs.getInt("id"));
   blog.setCategory_id(rs.getInt("category_id"));
   blog.setTitle(rs.getString("title"));
   blog.setContent(rs.getString("content"));
   blog.setCreated_time(rs.getDate("created_time"));
   list.add(blog);
  }
  return list;
 } catch (SQLException e) {
  e.printStackTrace();
 } finally {
  JDBCUtil.release(rs, ps, conn);
 }
 return null;
}
//总记录数
public int getTotal() {
 Connection conn = JDBCUtil.getConnection();
 PreparedStatement ps = null;
 ResultSet rs = null;
 try {
  ps = conn.prepareStatement("select count(*) from blog");
  rs = ps.executeQuery();
  if (rs.next()) {
   return rs.getInt(1);
  }
 } catch (SQLException e) {
  e.printStackTrace();
 } finally {
  JDBCUtil.release(rs, ps, conn);
 }
 return 0;
}
}

service层 

public class BlogService {
BlogDao blogDao = new BlogDao();
//返回pagebean,所有分页需要的信息都去pagebean里查找
public BlogPage findPageRecord(int pageno) {
 int totalrecord = blogDao.getTotal();
 BlogPage blogpage = new BlogPage(pageno, totalrecord);
 List<Blog> list = blogDao.getPageRecord(blogpage.getPagenostart(),blogpage.getPagesize());
 blogpage.setPagerecord(list);
 return blogpage;
}
}

servlet类 

@WebServlet("/BlogSplitServlet")
public class BlogSplitServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 request.setCharacterEncoding("UTF-8");
 response.setContentType("text/html; charset=utf-8");
 String pagenostr=request.getParameter("pageno");
 //首次访问servletpagenostr为null，给一个初始值，即默认访问第一页
 int pageno=1;
 if(pagenostr!=null)
  pageno=Integer.parseInt(pagenostr);
 BlogService service=new BlogService();
 BlogPage blogPage=service.findPageRecord(pageno);
 request.setAttribute("blogPage", blogPage);
 request.getRequestDispatcher("/blogPage.jsp").forward(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doGet(request, response);
}
}

这样所有的分页信息就封装到pagebean里了 

jsp实现只需要将pagebean里的信息取出来就行了 

下面给出我的jsp实现（模拟ligerUI） 

<％@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"％>
<％@page import="java.util.*,model.Blog,model.BlogPage"％>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript">
window.onload = function() {
 //保证select的option与当前页显示一致
 select = document.getElementById("select");
 pageno = '${blogPage.pageno}';
 select.options[pageno - 1].selected = 'selected';
}
//select下拉列表跳转
function selectjump() {
 var pageno = select.selectedIndex + 1;
 window.location.href = "http://localhost/jspPageSplit/BlogSplitServlet?pageno="
   + pageno;
}
//text跳转，onblur事件，输入框失去焦点是发生
function textjump() {
 var pageno = document.getElementById("text").value;
 window.location.href = "http://localhost/jspPageSplit/BlogSplitServlet?pageno="
   + pageno;
}
</script>
</head>
<body>
<％
 BlogPage blogPage = (BlogPage) request.getAttribute("blogPage");
 List<Blog> list = blogPage.getPagerecord();
 // 尾页填充空白行，若不填充，尾页表格tr行数与前面不一致很难看
 if (list.size() < blogPage.getPagesize()) {
  for (int i = list.size(); i < blogPage.getPagesize(); i++)
   list.add(null);
 }
％>
<div style="width: 50％; height: 400px">
 <table border="1" cellspacing="0" width="100％" bgcolor="#CEF0C5">
  <tr height="40px">
   <td>id</td><td>标题</td><td>内容</td><td>创建时间</td>
  </tr>
  <％
   for (Blog blog : list) {
    if (blog != null) {
  ％>
  <tr height="50px">
   <td width="10％"><％=blog.getId()％></td>
   <td width="20％"><％=blog.getTitle()％></td>
   <td width="40％"><％=blog.getContent()％></td>
   <td width="30％"><％=blog.getCreated_time()％></td>
  </tr>
  <!-- 尾页空白行填充 -->
  <％} else {％>
  <tr height="50px">
   <td width="10％"></td>
   <td width="20％"></td>
   <td width="40％"></td>
   <td width="30％"></td>
  </tr>
  <％}}％>
 </table>
 <div style="height:50px;background-color: #4B7DB3;line-height: 40px;">
 &nbsp;&nbsp;
 <!-- select下拉框 -->
 <select id="select">
  <％for (int i = 1; i <= blogPage.getTotalpage(); i++) {％>
  <option onclick="selectjump()"><％=i％></option>
  <％}％>
 </select>
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=1">首页</a>
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=<％=blogPage.getPageno()-1<1?blogPage.getPageno():blogPage.getPageno()-1％>">上一页</a>&nbsp;&nbsp;
 <input type="text" id="text" size="1px" value="${blogPage.pageno}" onblur="textjump()">/${blogPage.totalpage}
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=<％=blogPage.getPageno()+1>blogPage.getTotalpage()?blogPage.getPageno():blogPage.getPageno()+1％>">下一页</a>
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=<％=blogPage.getTotalpage()％>">尾页</a>
 <div style="float: right;">
 显示从${blogPage.pagenostart+1}到${blogPage.pageno==blogPage.totalpage?blogPage.totalrecord:blogPage.pagesize},
 共${blogPage.totalrecord}条. 每页显示${blogPage.pagesize}条
 </div>
 </div>
</div>
</body>
</html>

这是最后的样子，样式粗略的调了下，功能跟ligerUI默认的分页一模一样 

将JSP中代码改为标签（JSTL，需引入相应的jar包）并将JSP中的尾页补白放在servlet中后 

servlet中加入 

// 尾页填充空白行，若不填充，尾页表格tr行数与前面不一致很难看
 List<Blog> list = blogPage.getPagerecord();
 if (list.size() < blogPage.getPagesize()) {
  for (int i = list.size(); i < blogPage.getPagesize(); i++)
   list.add(null);
 }
 blogPage.setPagerecord(list);

jsp页面 

<％@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"％>
<％@page import="java.util.*,model.Blog,model.BlogPage"％>
<％@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"％>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Insert title here</title>
<script type="text/javascript">
//select下拉列表跳转
function selectjump() {
 var select = document.getElementById("select");
 var pageno = select.selectedIndex + 1;
 window.location.href = "http://localhost/jspPageSplit/BlogSplitServlet?pageno="
   + pageno;
}
//text跳转，onblur事件，输入框失去焦点时发生
function textjump() {
 var pageno = document.getElementById("text").value;
 window.location.href = "http://localhost/jspPageSplit/BlogSplitServlet?pageno="
   + pageno;
}
</script>
</head>
<body>
<div style="width: 50％; height: 400px">
 <table border="1" cellspacing="0" width="100％" bgcolor="#CEF0C5">
  <tr height="40px">
   <td>id</td><td>标题</td><td>内容</td><td>创建时间</td>
  </tr>
  <c:forEach items="${blogPage.pagerecord}" var="c" varStatus="vs">
  <c:if test="${c!=null}">
     <tr height="50px">
   <td width="10％">${c.id}</td>
   <td width="20％">${c.title}</td>
   <td width="40％">${c.content}</td>
   <td width="30％">${c.created_time}</td>
  </tr>
  </c:if>
  <!-- 尾页空白行填充 -->
  <c:if test="${c==null}">
  <tr height="50px">
   <td width="10％"></td>
   <td width="20％"></td>
   <td width="40％"></td>
   <td width="30％"></td>
  </tr>
  </c:if>
  </c:forEach>
 </table>
 <div style="height:50px;background-color: #4B7DB3;line-height: 40px;">
 &nbsp;&nbsp;
 <!-- select下拉框 -->
 <select id="select">
 <c:forEach begin="1" end="${blogPage.totalpage}" var="i">
 <option value="${i}" onclick="selectjump()" ${blogPage.pageno==i?'selected="selected"':''}>${i}</option>
 </c:forEach>
 </select>
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=1">首页</a>
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=${blogPage.pageno-1<1?blogPage.pageno:blogPage.pageno-1}">上一页</a>&nbsp;&nbsp;
 <input type="text" id="text" size="1px" value="${blogPage.pageno}" onblur="textjump()">/${blogPage.totalpage}
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=${blogPage.pageno+1>blogPage.totalpage?blogPage.pageno:blogPage.pageno+1}">下一页</a>
 <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=${blogPage.totalpage}">尾页</a>
 <div style="float: right;">
 显示从${blogPage.pagenostart+1}到${blogPage.pageno==blogPage.totalpage?blogPage.totalrecord:blogPage.pagesize},
 共${blogPage.totalrecord}条. 每页显示${blogPage.pagesize}条
 </div>
 </div>
</div>
</body>
</html>

 实际运用中可以根据需求编写jsp页面，但是后台代码基本是通用的