图书管理系统MVC模式_分页（EL&JSTL)

野性酷女 2022-05-19 05:12 181阅读 0赞

登陆页面login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <!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>登陆页面</title>
    </head>
    <body>
    <% String flag = (String)request.getAttribute("flag"); if(flag!=null){ out.print("<div style='font-size:36px;color:red;text-align:center'>"+flag+"</div>"); } %>
    <form action="LoginServlet01" method="get">
        <table align="center" width="500px" frame="box" rules="rows">
            <tr><td>用户名</td><td><input type="text" size="20" name="username"></td></tr>
            <tr><td>密码</td><td><input type="password" size="20" name="password"></td></tr>
            <tr><td colspan="2"><input type="submit" value="登录"></td></tr>
        </table>
    </form>
    </body>
    </html>

model包下建Book.java

package model;
    
    public class Book { 
        private String id;
        private String name;
        private String author;
        private String publish;
        private Double price;
        private String des;
    
        public Book() {
            super();
        }
        public String getId() {
            return id;
        }
        public void setId(String id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getAuthor() {
            return author;
        }
        public void setAuthor(String author) {
            this.author = author;
        }
        public String getPublish() {
            return publish;
        }
        public void setPublish(String publish) {
            this.publish = publish;
        }
        public Double getPrice() {
            return price;
        }
        public void setPrice(Double price) {
            this.price = price;
        }
        public String getDes() {
            return des;
        }
        public void setDes(String des) {
            this.des = des;
        }
    }

注：其中调用JdbcUtil.java工具类，详细参考本人CSDN博客文章[JdbcUtil工具类][JdbcUtil]

package controller;
    
    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.Statement;
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.junit.Test;
    
    import JdbcUtil.JdbcUtil;
    import model.Book;
    
    /** * Servlet implementation class LoginServlet */
    @WebServlet("/LoginServlet01")
    public class LoginServlet01 extends HttpServlet { 
        JdbcUtil jdbc=new JdbcUtil();
        /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //设置请求的编码格式
            request.setCharacterEncoding("UTF-8");
            String username=request.getParameter("username");
            String passward=request.getParameter("password");
    
            boolean flag=query(username,passward);
    
            if(flag) {
                //将request转为session保存用户名
                request.getSession().setAttribute("username", username);
                //页面跳转QueryServlet作页码查询控制操作
                request.getRequestDispatcher("QueryServlet").forward(request,response);
            }else {
                request.setAttribute("flag", "用户名或密码错误，请重新输入");
                request.getRequestDispatcher("login.jsp").forward(request, response);
            }
        }
    
    
        public List<Book> query_book() {
            try {
                String sql="select * from tb_book";
                ResultSet rs=jdbc.Query(sql,null);
                List<Book> books=new ArrayList<Book>();
                while(rs.next()) {
                    Book book=new Book();
                    book.setId(rs.getString(1));
                    book.setName(rs.getString(2));
                    book.setAuthor(rs.getString(3));
                    book.setPublish(rs.getString(4));
                    book.setPrice(rs.getDouble(5));
                    book.setDes(rs.getString(6));
                    books.add(book);
                }
                return books;
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                jdbc.close();
            }
            return null;
        }
    
    
        public boolean query(String username,String password) {
            try {
    
                String sql="select * from tb_users where username=? and password=?";
                ResultSet rs=jdbc.Query(sql, username,password);
                if(rs.next()) {
                    return true;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }   finally {
                jdbc.close();
            }
            return false;
        }
    
        /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request, response);
        }
    
    }

flag为false时跳转QueryServlet(注解的跳转地址)，同在controller下的QueryServlet.java

package controller;
    
    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.junit.Test;
    
    import JdbcUtil.JdbcUtil;
    import model.Book;
    import util.CommonUtil;
    
    /** * Servlet implementation class LoginServlet */
    @WebServlet("/QueryServlet")
    public class QueryServlet extends HttpServlet { 
        JdbcUtil jdbc=new JdbcUtil();
        /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            try {
                String index=request.getParameter("pageIndex");
                int pageindex=1;
                if(index!=null) {
                    pageindex=Integer.parseInt(index);
                }
                //传递页码到jsp页面
                request.setAttribute("pageIndex", pageindex);
    
                String sql="select * from tb_book limit " +(pageindex-1)*CommonUtil.pageSize+","+CommonUtil.pageSize+"";
                ResultSet rs=jdbc.Query(sql,null);
                List<Book> books=new ArrayList<Book>();
                while(rs.next()) {
                    Book book=new Book();
                    book.setId(rs.getString(1));
                    book.setName(rs.getString(2));
                    book.setAuthor(rs.getString(3));
                    book.setPublish(rs.getString(4));
                    book.setPrice(rs.getDouble(5));
                    book.setDes(rs.getString(6));
                    books.add(book);
                }
    
                //求总页数
                int totalCount=totalCount();
                int totalPage=totalCount%CommonUtil.pageSize==0?totalCount/CommonUtil.pageSize:totalCount/CommonUtil.pageSize+1;
    
                request.setAttribute("pageIndex", pageindex);
                request.setAttribute("totalPage", totalPage);
                //传递列表结果集到JSP页面
                request.setAttribute("books", books);
                //传递列表的结果集到JSP页面
                request.getRequestDispatcher("index.jsp").forward(request, response);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                jdbc.close();
            }
    
        }
    
        private int totalCount() {
            try {
                String sql="select count(*) from tb_book";
                ResultSet rs=jdbc.Query(sql, null);
                int totalCount=0;
                if(rs.next()) {
                    totalCount=rs.getInt(1);
                }
                return totalCount;
            } catch (SQLException e) {
                e.printStackTrace();
            }
            return 0;
        }
    
    
        /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request, response);
        }
    
    }

util包下的CommonUtil.java设置每页显示的条数

package util;
    
    public class CommonUtil {
        public static int pageSize=5;//每页显示5条
    }

成功页面index.jsp(EL&JSTL)

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" import="java.util.*,model.*"%>
    <%@ 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>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>成功登陆页面</title>
    </head>
    <body>
        欢迎用户：${username }  登陆系统!!!
        <table align="center" frame="box" rules="all" width="600px">
            <thead>
            <th>id</th>
            <th>name</th>
            <th>author</th>
            <th>publish</th>
            <th>price</th>
            <th>des</th>
            </thead>
            <tbody>
            <c:forEach items="${books}" var="book">
            <tr>
                <td>${book.id }</td>
                <td>${book.name }</td>
                <td>${book.author }</td>
                <td>${book.publish }</td>
                <td>${book.price }</td>
                <td>${book.des }</td>
            </tr>
            </c:forEach>
            </tbody>
        </table>
        <a href="QueryServlet?pageIndex=1">首页</a>  
    
        <c:if test="${pageIndex!=1 }">
        <a href="QueryServlet?pageIndex=${pageIndex-1 }">上一页</a>  
        </c:if>
    
        
        <c:forEach begin="1" end="${totalPage }" varStatus="status">
            <a href="QueryServlet?pageIndex=${status.index }">${status.index }</a>  
        </c:forEach>
        ...  
        <c:if test="${pageIndex!=totalPage }">
        <a href="QueryServlet?pageIndex=${pageIndex+1 }">下一页</a>  
        <a href="QueryServlet?pageIndex=${totalPage }">尾页</a>  
        </c:if>
    </body>
    </html>

[JdbcUtil]: https://blog.csdn.net/qq_41589293/article/details/81138070