Servlet + JSP 数据分页的实现
浏览数：28 /
时间：2015年06月09日
本篇数据分页的实现，采用Oracle 数据库，获取SCOTT 用户 EMP 表中的数据，分页将其显示出来。
1.首先创建一个对象 UserData，用以保存从数据库中获取的数据。
package com.tool; import java.math.BigDecimal; import java.util.Date; /** * Created by lx_sunwei on 14-1-6. */ public class UserData { /** * EMP表中的数据属性 */ private String ename; private String job; private BigDecimal empno; private BigDecimal mgr; private Date hireDate; private BigDecimal sal; private BigDecimal comm; private BigDecimal deptno; public BigDecimal getEmpno() { return empno; } public void setEmpno(BigDecimal empno) { this.empno = empno; } public BigDecimal getMgr() { return mgr; } public void setMgr(BigDecimal mgr) { this.mgr = mgr; } public Date getHireDate() { return hireDate; } public void setHireDate(Date hireDate) { this.hireDate = hireDate; } public BigDecimal getSal() { return sal; } public void setSal(BigDecimal sal) { this.sal = sal; } public BigDecimal getComm() { return comm; } public void setComm(BigDecimal comm) { this.comm = comm; } public BigDecimal getDeptno() { return deptno; } public void setDeptno(BigDecimal deptno) { this.deptno = deptno; } public String getEname() { return ename; } public void setEname(String ename) { this.ename = ename; } public String getJob() { return job; } public void setJob(String job) { this.job = job; } }
2.创建一个 DBHelper 对象用以与数据库进行交互
package com.dao; import com.tool.UserData; import java.math.BigDecimal; import java.sql.*; import java.util.*; import java.util.Date; /** * Created by lx_sunwei on 14-1-6. */ public class DBHelper { Connection conn; //数据库连接对象 PreparedStatement pt; //SQL语句预处理对象 ResultSet rs; //结果集对象 public DBHelper(){ try { Class.forName("oracle.jdbc.driver.OracleDriver"); //装载驱动 } catch (ClassNotFoundException e) { e.printStackTrace(); } } /** * 获取当前页的数据 * @param curPage * @param rowsPerPage * @return */ public List<UserData> getData(int curPage, int rowsPerPage) { List<UserData> dataList = new ArrayList<>(); String url = "jdbc:oracle:thin:@localhost:1521:orcl"; try { conn = DriverManager.getConnection(url,"scott","tiger"); String sql = "select * from emp where rownum <= ((? - 1) * "+rowsPerPage+" + "+rowsPerPage+") minus " + " select * from emp where rownum <= (? - 1) * "+rowsPerPage+" "; pt = conn.prepareStatement(sql); pt.setInt(1,curPage); pt.setInt(2,curPage); rs = pt.executeQuery(); while (rs.next()){ /** * 从结果集中取得数据 */ UserData userData = new UserData(); BigDecimal empno = rs.getBigDecimal("empno"); String ename = rs.getString("ename"); String job = rs.getString("job"); BigDecimal mgr = rs.getBigDecimal("mgr"); Date hireDate = rs.getDate("hiredate"); BigDecimal sal = rs.getBigDecimal("sal"); BigDecimal comm = rs.getBigDecimal("comm"); BigDecimal deptno = rs.getBigDecimal("deptno"); /** * 设置对象属性 */ userData.setEmpno(empno); userData.setEname(ename); userData.setJob(job); userData.setMgr(mgr); userData.setHireDate(hireDate); userData.setSal(sal); userData.setComm(comm); userData.setDeptno(deptno); dataList.add(userData); //把对象添加集合中 } rs.close(); pt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } return dataList; } /** * 返回总页数 * @return */ public int getMaxPage(int rowsPerPage) { int maxPage; int maxRowCount = 0; String url = "jdbc:oracle:thin:@localhost:1521:orcl"; try { conn = DriverManager.getConnection(url,"scott","tiger"); //创建数据库连接 String sql = "select count(*) from emp"; pt = conn.prepareStatement(sql); rs = pt.executeQuery(); if (rs.next()){ maxRowCount = rs.getInt(1); //总行数 } } catch (SQLException e) { e.printStackTrace(); } maxPage = (maxRowCount + rowsPerPage - 1) / rowsPerPage; //总页数 return maxPage; } }
3.创建 Servlet 对显示页面进行控制
package com.servlet; import com.dao.DBHelper; import com.tool.UserData; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.util.*; /** * Created by lx_sunwei on 14-1-6. */ public class Servlet extends HttpServlet { public int rowsPerPage; //每页显示的行数 public int curPage; //当前页页码 public int maxPage; //总共页数 DBHelper db = new DBHelper(); public Servlet(){ rowsPerPage = 5; } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String curPage1 = request.getParameter("page"); //获取当前页页码 if (curPage1 == null){ curPage = 1; request.setAttribute("curPage",curPage); //设置curPage对象 }else { curPage = Integer.parseInt(curPage1); if (curPage < 1){ curPage = 1; } request.setAttribute("curPage",curPage); } List<UserData> dataList; dataList = db.getData(curPage,rowsPerPage); //获取当前页的数据 maxPage = db.getMaxPage(rowsPerPage); //获取总页数 request.setAttribute("dataList",dataList); request.setAttribute("maxPage", maxPage); RequestDispatcher rd = request.getRequestDispatcher("pagemain.jsp"); //将请求转发到pagemain.jsp页面 rd.forward(request,response); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request,response); } }
4.创建 JSP 页面，显示数据。
<%@ page import="java.util.List" %> <%@ page import="com.tool.UserData" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>servlet数据分页</title> <link rel="stylesheet" type="text/css" href="css.css"> </head> <body> <div style="margin-top: 15%; margin-left: 25%"> <table> <caption>SCOTT用户，EMP表中的数据</caption> <%! int curPage,maxPage; %> <% curPage =Integer.parseInt(request.getAttribute("curPage").toString()); %> <!--取得当前页--> <% maxPage =Integer.parseInt((String)request.getAttribute("maxPage").toString()); %> <!--取得总页数--> <%if (request.getAttribute("dataList") == null){ %> <tr> <td colspan="8">没有数据</td> </tr> <% }else { %> <tr> <!--表头--> <th>EMPNO</th> <th>ENAME</th> <th>JOB</th> <th>MGR</th> <th>HIREDATE</th> <th>SAL</th> <th>COMM</th> <th>DEPTNO</th> </tr> <% List list = (List) request.getAttribute("dataList"); for (Object aList : list) { UserData userData = (UserData) aList; %> <tr> <!--取得表中数据--> <td><%= userData.getEmpno() %></td> <td><%= userData.getEname() %></td> <td><%= userData.getJob() %></td> <td><%= userData.getMgr() %></td> <td><%= userData.getHireDate() %></td> <td><%= userData.getSal() %></td> <td><%= userData.getComm() %></td> <td><%= userData.getDeptno() %></td> </tr> <% } } %> </table> </div> <div style="margin-top: 8%; margin-left: 29%"> 第<%= curPage %>页，共<%= maxPage %>页 <%if (curPage > 1){ %> <a href="Servlet?page=1">首页</a> <a href="Servlet?page=<%=curPage - 1%>">上一页</a> <% }else { %> 首页 上一页 <% }%> <%if (curPage < maxPage){ %> <a href="Servlet?page=<%=curPage + 1%>">下一页</a> <a href="Servlet?page=<%=maxPage %>">尾页</a> <% }else { %> 下一页 尾页 <% }%> 转至第 <form name="form1" action="Servlet" method="get"> <label> <select name="page" onchange="document.form1.submit()"> <%for ( int i = 1; i <= maxPage; i++){ if (i == curPage){ %> <!--当前页页码默认选中--> <option selected value="<%= i%>"><%= i %></option> <% }else { %> <option value="<%= i %>"><%= i %></option> <% } }%> </select> </label> </form> 页 </div> </body> </html>
web.xml 中的配置文件为：
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <servlet> <servlet-name>Servlet</servlet-name> <servlet-class>com.servlet.Servlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>Servlet</servlet-name> <url-pattern>/Servlet</url-pattern> </servlet-mapping> </web-app>
把项目部署到 Tomcat 服务器上，输入地址：http://localhost:8080/Servlet 显示如下页面
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