jsp分页

左手的ㄟ右手 2022-06-04 08:24 225阅读 0赞

效果如下:

![这里写图片描述][SouthEast]

jsp

<%@page import="com.cyh.test.Student"%>
    <%@ page language="java" contentType="text/html; charset=gb2312" %>
    <%@ page language="java" import="java.util.*" %>
          <title></title>
        </head>
    <html>
    
        <% List<Student> list = (ArrayList<Student>)request.getAttribute("list"); if (list == null){System.out.println("为null");%>
             <jsp:forward page="/myServlet?page=1"/>
       <% } %>
        <body>
           <table border="1">
                <tr>
                    <td>编号</td>
                    <td>学号</td>
                    <td>姓名</td>
                    <td>年龄</td>
                </tr>
                    <% for (Student stu : list){%>
                        <tr>
                            <td><%=stu.getId()%></td>
                            <td><%=stu.getNumber() %></td>
                            <td><%=stu.getName() %></td>
                            <td><%=stu.getAge() %></td>
                        </tr>
                        <% } %>
                    <td>
                        <%=request.getAttribute("bar") %>
                    </td>
                </tr>
           </table>
        </body>
    </html>

dao类

public class Dao { 
        public Connection getConnection(){
            Connection conn = null;
            try {
                Class.forName("com.mysql.jdbc.Driver");
                String url = "jdbc:mysql://localhost:3307/student";
                String user="root";
                String password="1234";
                conn = DriverManager.getConnection(url,user,password);
            } catch (Exception e) {
                // TODO 自动生成的 catch 块
                e.printStackTrace();
            }
            return conn;
        }
        /** * 查询指定页（page这页）的记录 * @param page * @return */
        public List<Student> find(int page){
            List<Student> list = new ArrayList<Student>();
            Connection conn = getConnection();
            String sql = "select * from tb_stu limit ?,?";
            try {
                PreparedStatement ps = conn.prepareStatement(sql);
    
                ps.setInt(1, (page-1)*Student.PAGE_SIZE);
                ps.setInt(2, Student.PAGE_SIZE);
                ResultSet rs = ps.executeQuery();
                while(rs.next()){
                    Student stu = new Student();
                    stu.setId(rs.getInt("id"));
                    stu.setNumber(rs.getInt("number"));
                    stu.setName(rs.getString("name"));
                    stu.setAge(rs.getInt("age"));
                    list.add(stu);
                }
                rs.close();
                ps.close();
                conn.close();
    
            } catch (Exception e) {
                // TODO 自动生成的 catch 块
                e.printStackTrace();
            }
    
            return list;
        }
    
        /** * 总记录数 * @return */
        public int findCount(){
            int count = 0;
            Connection conn = getConnection();
            String sql = "select count(*) from tb_stu";
            Statement sta;
            try {
                sta = conn.createStatement();
                ResultSet rs = sta.executeQuery(sql);
                if (rs.next()){
                    count = rs.getInt(1);
                }
                rs.close();
                sta.close();
                conn.close();
            } catch (Exception e) {
                // TODO 自动生成的 catch 块
                e.printStackTrace();
            }
            return count;
        }
    }

servlet

import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.List;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class MyServlet extends HttpServlet { 
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            int currPage = 1;
            if (request.getParameter("page") == null){
                currPage = 1;
            }else{
                currPage = Integer.parseInt(request.getParameter("page"));
            }
            System.out.println(currPage+","+request.getParameter("page"));
            Dao dao = new Dao();
            List<Student> list = dao.find(currPage);
            request.setAttribute("list", list);
            int pages;
            int count = dao.findCount();
            if (count % Student.PAGE_SIZE == 0){
                pages = count/Student.PAGE_SIZE; //分为几页
            }else{
                pages = count / Student.PAGE_SIZE+1; //多余的增加一列
            }
            StringBuffer sb = new StringBuffer();
    
            if (currPage != 1){
                sb.append("<a href='myServlet?page="+(currPage-1)+"'>"+"上一页"+"</a>");
                sb.append(" ");
            }
            for (int i=1; i<= pages; i++){
                if(i == currPage){
                    sb.append("["+i+"]");
                }else{
                    sb.append("<a href='myServlet?page="+i+"'>"+i+"</a>");
                    sb.append(" ");
                }
            }
            if (currPage != pages){
                sb.append("<a href='myServlet?page="+(currPage+1)+"'>"+"下一页"+"</a>");
            }
            System.out.println(sb.toString());
            System.out.println("当前"+currPage);
            request.setAttribute("bar", sb.toString());
            request.getRequestDispatcher("").forward(request, response);
        }
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
        }
    
    }

bean类

public class Student {
        public static final int PAGE_SIZE=2; //每页显示的数量
    
        private int id;
        private int number;
        private String name;
        private int age;
    
        public int getNumber() {
            return number;
        }
        public void setNumber(int number) {
            this.number = number;
        }
        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;
        }
    
    }

[SouthEast]: /images/20220604/bdb1900bcf3443ea91e528d860182528.png