Jsp的分页操作源代码

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一  分页操作的分析：
1．层的问题
    Com.csdn.domaim
    Com.csdn.dao
    Com.csdn.daoImpl
    Com.csdn.service 接口
    Com.csdn.serviceImpl 实现类
    Com.csdn.web 控制器
    Com.csdn.web.filter
    Com.csdn.web.listener
    Com.csdn.util
 
2．如何实现的问题
    StuentBean中定义了几个私有的属性：   id  name   age  address  
    StudentDao接口用于实现对数据库中属性的封装。
    StudntService接口：定义方法，用数据库处理的方法
    StudentServicImpl实现类
    ControllerService：控制器：接收客户端的请求
    List.jsp  显示所有的信息
 
3．分页显示：
    首先先检查是否与数据库连接，可以先把所有的都输出。
    然后要点击浏览器中的超链接来获取从数据库中读取的数据并显示，在超链接的时候要传参数，通过对servlet层的访问，在servlet层中对从数据库中的数据进行读取之后，通过判断再把参数传给浏览器并显示从数据库中调用的数据
二   代码的实现和说明
1．首先创建数据库，如图：
并从数据库中插入数据
2．在java中把数据库中的数据封装成类  StudentBean.java
public class StudentBean {
    private int id;
    private String name;
    private int age;
    private String address;
    public StudentBean() {
       super();
       // TODO Auto-generated constructor stub
    }
    public StudentBean(int id, String name, int age, String address) {
       super();
       this.id = id;
       this.name = name;
       this.age = age;
       this.address = address;
    }
    public int getId() {
       return id;
    }
    public void setId(int id) {
       this.id = id;
    }
    public String getName() {
       return name;
    }
    public void setName(String name) {
       this.name = name;
    }
    public int getAge() {
       return age;
    }
    public void setAge(int age) {
       this.age = age;
    }
    public String getAddress() {
       return address;
    }
    public void setAddress(String address) {
       this.address = address;
    }
    @Override
    public String toString() {
       return "StudentBean [address=" + address + ", age=" + age + ", id="
              + id + ", name=" + name + "]";
    }
   
}
3.创建实现对数据库数据的查找和分页的查找，首先先创建一个dao层，并在dao层写上一个接口和一个daoImpl两个java类，接口是为了在service层中与servetl成的连接，首先创建StudentDao.java
import java.util.List;
import com.hbsi.domain.StudentBean;
public interface StudentDao {
    //返回所有记录行
    public List<StudentBean> findAll();
    //返回指定页中显示的记录行（一共有多少页，共多长）
    public List<StudentBean> listPage(int currentPage,int pageSize);
    //返回所有记录的行数
    public int getSize();
}
再创建实现类  StudentDaoImpl.java
package com.hbsi.dao;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;
 
import com.hbsi.domain.StudentBean;
//接口的实现类
public class StudentDaoImpl implements StudentDao {
 
    //声明操作的数据库对象
    private static Connection conn;
    private PreparedStatement pstmt;
    private ResultSet rs;
   
    //第一步：准备驱动程序，构造到项目路径中
    private static final String URL="jdbc:mysql://localhost:3306/demo?user=root&password=qiao&useUnicode=true&characterEncoding=utf8";
   
    static{
       try {
           //第二步：加载驱动程序
           Class.forName("com.mysql.jdbc.Driver");
           //第三步:获取连接对象
           conn = DriverManager.getConnection(URL);
       } catch (ClassNotFoundException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
    }
   
    private int size;//记录多少行
    public List<StudentBean> findAll() {
       //存放读取的数据
       List<StudentBean> list = new LinkedList<StudentBean>();
       try {
           pstmt = conn.prepareStatement("select * from student");
           rs = pstmt.executeQuery();
           //从结果集中读取
           while(rs.next()){
              StudentBean s = new StudentBean();
              s.setId(rs.getInt(1));
              s.setName(rs.getString(2));
              s.setAge(rs.getInt(3));
              s.setAddress(rs.getString(4));
              list.add(s);
           }
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
       size=list.size();
       return list;
    }
 
    //获取总的记录行数
    public int getSize() {
       // TODO Auto-generated method stub
       findAll();
       return size;
    }
 
    //截取的读取
    public List<StudentBean> listPage(int currentPage, int pageSize) {
       //存放读取的数据
       List<StudentBean> list = new LinkedList<StudentBean>();
       try {
           //记录行
           int recordIndex=(currentPage-1)*pageSize;
           pstmt = conn.prepareStatement("select * from student limit ?,?");
           int index =1;
           pstmt.setInt(index++, recordIndex);
           pstmt.setInt(index++, pageSize);
 
           //从结果集中读
           rs = pstmt.executeQuery();
           while(rs.next()){
              StudentBean s = new StudentBean();
              s.setId(rs.getInt(1));
              s.setName(rs.getString(2));
              s.setAge(rs.getInt(3));
              s.setAddress(rs.getString(4));
              list.add(s);
           }
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
       return list;
    }
 
}
4.service层是业务层，是是和其他接口的层
首先创建StudentService.java
package com.hbsi.service;
 
import java.util.List;
 
import com.hbsi.domain.StudentBean;
 
public interface StudentService {
    public List<StudentBean> findAll();
    public List<StudentBean> listPage(int currentPage,int pageSzie);
    //得到所有的记录行
    public int getSize();
}
再创建StudentserviceImpl.java
 
package com.hbsi.service;
 
import java.util.List;
 
import com.hbsi.dao.StudentDaoImpl;
import com.hbsi.domain.StudentBean;
 
public class StudentServceImpl implements StudentService {
 
    StudentDaoImpl dao = new StudentDaoImpl();
   
    public List<StudentBean> findAll() {
       // TODO Auto-generated method stub
       return dao.findAll();
    }
 
    public List<StudentBean> listPage(int currentPage, int pageSize) {
       // TODO Auto-generated method stub
       return dao.listPage(currentPage, pageSize);
    }
 
    public int getSize() {
       // TODO Auto-generated method stub
       return dao.getSize();
    }
 
}
5.jsp页面的实现  list.jsp
    <%@ page language="java" import="java.util.*,com.hbsi.domain.*"
    pageEncoding="utf-8"%>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://"
           + request.getServerName() + ":" + request.getServerPort()
           + path + "/";
%>
 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
       <base href="<%=basePath%>">
 
       <title>My JSP 'list.jsp' starting page</title>
 
       <meta http-equiv="pragma" content="no-cache">
       <meta http-equiv="cache-control" content="no-cache">
       <meta http-equiv="expires" content="0">
       <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
       <meta http-equiv="description" content="This is my page">
       <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
 
    </head>
 
    <body>
       <!-- 读取集合中 的数据 -->
       <%
           List<StudentBean> list = (List<StudentBean>) request.getAttribute("list");
           int pageNo = Integer.parseInt(request.getParameter("pageNo"));
       %>
       <h3>
           学生信息表
       </h3>
       <!-- 读取 -->
       <table>
       <%
           for (int i = 0; i < list.size(); i++) {
       %>
 
       <tr>
           <td><%=list.get(i).getId() %></td>
           <td><%=list.get(i).getName() %></td>
           <td><%=list.get(i).getAge()%></td>
           <td><%=list.get(i).getAddress() %></td>
       </tr>
       <%
           }
       %>
   
 
       </table><br/>
       <a href="listStudent?pageNo=1">第一页</a> <a href="listStudent?pageNo=<%=pageNo-1 %>">上一页</a> <a href="listStudent?pageNo=<%=pageNo+1 %>">下一页</a> <a href="">最后页</a>
    </body>
</html>
6.servlet层的实现  ControllerServlet.java
package com.hbsi.web;
 
import java.io.IOException;
import java.util.List;
 
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import com.hbsi.domain.StudentBean;
import com.hbsi.service.StudentServceImpl;
 
public class ControllerServlet extends HttpServlet {
 
    /**
     *
     */
    private static final long serialVersionUID = 1L;
 
    public ControllerServlet() {
       super();
    }
 
    public void destroy() {
       super.destroy(); // Just puts "destroy" string in log
       // Put your code here
    }
 
    public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
 
       doPost(request, response);
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       // 通过服务层得到数据
       StudentServceImpl service = new StudentServceImpl();
       // List<StudentBean> list = service.findAll();
 
       // 分页的操作
       // 计算一下一共有多少页
       int total = service.getSize();// 一共有多少行记录
       int pageSize = 3;// 每页显示的记录行数
       int totalPages = total / pageSize;//共有多少个页面显示
       totalPages = (total % pageSize == 0) ? totalPages : totalPages + 1;// 总共有total页
      
       //显示的页数
       int currentPage = 1;
       if (request.getParameter("pageNo") != null) {
           currentPage = Integer.parseInt(request.getParameter("pageNo"));
       }
       if (currentPage < 1) {
           currentPage = 1;
       }
       if(currentPage>totalPages){
           currentPage=totalPages;
       }
      
       List<StudentBean> list =service.listPage(currentPage, pageSize);
       // servlt和jsp的桥梁,设置作用域的范围
       request.setAttribute("list", list);
 
       // 通过jsp页面显示所有的数据,请求的转向
       RequestDispatcher rd = request.getRequestDispatcher("list.jsp?pageNo="+currentPage);
       rd.forward(request, response);
 
    }
 
    public void init() throws ServletException {
       // Put your code here
    }
}
 