servlet分页代码示例

飞奔的炮台

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="https://java.sun.com/xml/ns/javaee"
       xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="https://java.sun.com/xml/ns/javaee
      https://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：https://localhost:8080/Servlet   这样就可以看到效果