Java Web总结十三之二分页

一、分页代码类结构：

二、每个类具体代码

1、DbConfig.properties：

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/mydb3
user=root
password=root

2、IUserDao.java：

package com.gnnuit.web.fy.dao;

import java.util.List;

import com.gnnuit.web.fy.domain.UserInfo;

public interface IUserDao {
    // 获取每一页的详细信息
    public List<UserInfo> find(int start, int size);

    // 获取总记录数
    public int getAllRecordNo();
}

3、UserDao.java：

package com.gnnuit.web.fy.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.gnnuit.web.fy.domain.UserInfo;
import com.gnnuit.web.fy.util.JdbcUtill;

public class UserDao implements IUserDao {

    @Override
    public List<UserInfo> find(int start, int size) {
        List<UserInfo> userInfos = new ArrayList<>();
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql = "select * from user limit ?,?";
        try {
            conn = JdbcUtill.getMySqlConnection();
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, start);
            pstmt.setInt(2, size);
            rs = pstmt.executeQuery();
            while (rs.next()) {
                UserInfo info = new UserInfo();
                String id = rs.getString("id");
                String username = rs.getString("username");
                String password = rs.getString("password");
                java.sql.Date birthday = rs.getDate("birthday");
                int salary = rs.getInt("salary");

                info.setBirthday(birthday);
                info.setId(Integer.parseInt(id));
                info.setPassword(password);
                info.setSalary(salary);
                info.setUsername(username);

                userInfos.add(info);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return userInfos;
    }

    @Override
    public int getAllRecordNo() {
        int sum = 0;
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql = "select count(*) from user";
        try {
            conn = JdbcUtill.getMySqlConnection();
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            if(rs.next()){
                sum=rs.getInt(1);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JdbcUtill.close(rs);
            JdbcUtill.close(pstmt);
            JdbcUtill.close(conn);
        }
        return sum;
    }

}

4、Page.java：

package com.gnnuit.web.fy.domain;

import java.util.ArrayList;
import java.util.List;

public class Page {
    private int allRecordNo;// 总记录数
    private int perPageNo = 5;// 每页显示多少条记录
    private int allPageNo;// 总页数
    private int currentPageNo = 1;// 显示的当前页号
    private List<UserInfo> userinfos = new ArrayList<>();// 当前页的所有信息

    public Page() {

    }

    public int getAllRecordNo() {
        return allRecordNo;
    }

    public void setAllRecordNo(int allRecordNo) {
        this.allRecordNo = allRecordNo;
        if (allRecordNo % perPageNo == 0) {
            this.allPageNo = allRecordNo / perPageNo;
        } else {
            this.allPageNo = allRecordNo / perPageNo + 1;
        }
    }

    public int getPerPageNo() {
        return perPageNo;
    }

    public void setPerPageNo(int perPageNo) {
        this.perPageNo = perPageNo;
    }

    public int getAllPageNo() {
        return allPageNo;
    }

    public void setAllPageNo(int allPageNo) {
        this.allPageNo = allPageNo;
    }

    public int getCurrentPageNo() {
        return currentPageNo;
    }

    public void setCurrentPageNo(int currentPageNo) {
        this.currentPageNo = currentPageNo;
    }

    public List<UserInfo> getUserinfos() {
        return userinfos;
    }

    public void setUserinfos(List<UserInfo> userinfos) {
        this.userinfos = userinfos;
    }

}

5、UserInfo.java：

package com.gnnuit.web.fy.domain;

import java.util.Date;

public class UserInfo {
    private int id;
    private String username;
    private String password;
    private Date birthday;
    private int salary;

    public UserInfo() {

    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public int getSalary() {
        return salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }

}

6、DaoFactory.java：

package com.gnnuit.web.fy.factory;

import com.gnnuit.web.fy.dao.IUserDao;
import com.gnnuit.web.fy.dao.UserDao;

//操作数据库的工厂（单例）
public class DaoFactory {
    private static DaoFactory daoFactory;

    public static DaoFactory getDaoFactory() {
        if (daoFactory == null) {
            daoFactory = new DaoFactory();
        }
        return daoFactory;
    }

    private DaoFactory() {

    }

    public IUserDao getDao() {
        return new UserDao();
    }
}

7、UserService.java：

package com.gnnuit.web.fy.service;

import java.util.List;

import com.gnnuit.web.fy.dao.IUserDao;
import com.gnnuit.web.fy.domain.Page;
import com.gnnuit.web.fy.domain.UserInfo;
import com.gnnuit.web.fy.factory.DaoFactory;

public class UserService {
    private IUserDao dao = DaoFactory.getDaoFactory().getDao();

    // 获取当前页的详细信息
    public Page find(int currentPageNo) {
        Page page = new Page();
        page.setCurrentPageNo(currentPageNo);
        int allRecordNo = dao.getAllRecordNo();
        page.setAllRecordNo(allRecordNo);
        int size = page.getPerPageNo();
        int start = (page.getCurrentPageNo() - 1) * size;
        List<UserInfo> userinfos = dao.find(start, size);
        page.setUserinfos(userinfos);
        return page;
    }
}

8、JdbcUtill.java

package com.gnnuit.web.fy.util;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

//操作JDBC的工具类
public final class JdbcUtill {
    private static String driver;
    private static String url;
    private static String user;
    private static String password;

    // 静态代码块：读取配置文件
    static {
        Properties prop = new Properties();
        InputStream is = JdbcUtill.class.getClassLoader().getResourceAsStream(
                "com/gnnuit/web/fy/config/DbConfig.properties");
        try {
            prop.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver = prop.getProperty("driver");
        url = prop.getProperty("url");
        user = prop.getProperty("user");
        password = prop.getProperty("password");
    }

    // 静态代码块：建立数据库的连接
    static {
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取MySql数据库的连接
     * 
     * @return Connection对象
     * @throws SQLException
     */
    public static Connection getMySqlConnection() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    /**
     * 关闭与数据库的连接
     * 
     * @param rs
     * @throws SQLException
     */
    public static void close(ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public static void close(Statement stmt) {
        if (stmt != null) {
            try {
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public static void close(Connection conn) {
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

9、UserPageServlet.java：

package com.gnnuit.web.fy.web;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gnnuit.web.fy.domain.Page;
import com.gnnuit.web.fy.service.UserService;

public class UserPageServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String method = request.getParameter("method");
        if (method != null) {
            if("fy".equals(method)){
                this.fy(request, response);
            }
        } else {
            // 第一次访问没带参数，默认调用分页方法
            this.fy(request, response);
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

    }

    private void fy(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String currentPageNo = request.getParameter("currentPageNo");
        UserService userService = new UserService();
        if (currentPageNo == null) {
            // 第一次访问，不带参数,直接访问第一页
            Page page = userService.find(1);
            request.setAttribute("page", page);
            request.getRequestDispatcher("/fy.jsp").forward(request, response);
        } else {
            Page page = userService.find(Integer
                    .parseInt(currentPageNo));
            request.setAttribute("page", page);
            request.getRequestDispatcher("/fy.jsp").forward(request, response);
        }
    }

}

10、fy.jsp：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'fy.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">

<script type="text/javascript">
    function fy(i){
        var uri="/day13/UserPageServlet?method=fy&currentPageNo="+i;
        window.location.href=uri;
    }
</script>

</head>

<body>
    <table border="1" align="center" width="60%">
        <caption>用户详细信息</caption>
        <tr>
            <th>编号</th>
            <th>用户名</th>
            <th>密码</th>
            <th>生日</th>
            <th>期望薪水</th>
        </tr>
        <c:forEach var="user" items="${page.userinfos }">
            <tr>
                <td>${user.id }</td>
                <td>${user.username }</td>
                <td>${user.password }</td>
                <td>${user.birthday }</td>
                <td>${user.salary }</td>
            </tr>
        </c:forEach>
    </table>
    <c:forEach var="i" begin="1" end="${page.allPageNo }" step="1">
        <a href="/day13/UserPageServlet?method=fy&currentPageNo=${i }"
            style="text-decoration: none;">[${i }]&nbsp;</a>
    </c:forEach>
    <select onchange="fy(this.value)">
        <c:forEach var="i" begin="1" end="${page.allPageNo }">
            <option value="${i }" ${i==page.currentPageNo?'selected':'' }>${i }</option>
        </c:forEach>
    </select>
    <br/>
    当前第${page.currentPageNo }页/共${page.allPageNo }页/每页显示${page.perPageNo }条记录
</body>
</html>