Java——分页 Servlet + Jsp+Jdbc 有点瑕疵

1.创建数据库，插入多条数据

2.java连接DB

3.Person类：

package com.phome.po;

public class Person {
    private int id;
    private int age;
    private String name; 
    private String sex;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
　　//...Setter() And Getter();
}

4.Dao操作类：

public class PersonDao {
    /**
     * ADD
     * @param person
     * @return
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    public boolean add(Person person) throws ClassNotFoundException, SQLException {
        String sql = "Insert into Persons(name,age,sex) values(?,?,?)";
        Connection conn = null;
        PreparedStatement ps = null;
        boolean success = false;
        try {
            conn = DbUtil.getConnection();
            ps = conn.prepareStatement(sql);
            //设置参数
            ps.setString(1, person.getName());
            ps.setInt(2, person.getAge());
            ps.setString(3, person.getSex());
            //执行sql语句
            success = (ps.executeUpdate() > 0);
        } catch (SQLException e) {
            System.out.println("【PersonDao -> add()发生异常】
【异常信息】" + e.getErrorCode());
            throw e;
        } finally {
            DbUtil.close(ps);
            DbUtil.close(conn);
        }
        return success;
    }
    /**
     * Page List
     * @param pageIndex
     * @param pageSize
     * @param condition
     * @return
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    public List<Person> findByPaging(int pageIndex,int pageSize,String condition) throws ClassNotFoundException, SQLException{
        String sql = "Select * From Persons";
        if(condition != null){
            sql += " Where " + condition;
        }
        sql += " limit " + ((pageIndex - 1) * pageSize) + "," + pageSize ;
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        List<Person> persons = new ArrayList<Person>();
        try {
            conn = DbUtil.getConnection();
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
            while (rs.next()) {
                persons.add(rs2Person(rs));
            }
        } catch (SQLException e) {
            System.out.println("【PersonDao -> findByPaging()发生异常】" + "
【异常信息】"
                    + e.getMessage());
            throw e;
        } finally {
            DbUtil.close(rs);
            DbUtil.close(ps);
            DbUtil.close(conn);
        }
        return persons;
    }
    /**
     * 得到总数
     * @param condition
     * @return
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    public int getCount(String condition) throws ClassNotFoundException, SQLException{
        String sql = "Select count(*) From Persons";
        if(condition != null){
            sql += " Where " + condition;
        }
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        int count = 0;
        try {
            conn = DbUtil.getConnection();
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
            if(rs.next()){
                count = rs.getInt(1);
            }
        } catch (SQLException e) {
            System.out.println("【PersonDao ->getCount()发生异常】" + "
【异常信息】"
                    + e.getMessage());
            throw e;
        } finally {
            DbUtil.close(rs);
            DbUtil.close(ps);
            DbUtil.close(conn);
        }
        return count;
    }
    /**
     * 查询Person的结果集
     * @param rs
     * @return
     * @throws SQLException
     */
    private Person rs2Person(ResultSet rs) throws SQLException {
        Person person = null;
        try {
            person = new Person();
            person.setId(rs.getInt("Id"));
            person.setName(rs.getString("Name"));
            person.setAge(rs.getInt("Age"));
            person.setSex(rs.getString("Sex"));
        } catch (SQLException e) {
            System.out.println("【PersonDao -> rs2Person()发生异常】" + "
【异常信息】"
                    + e.getMessage());
            throw e;
        }
        return person;
    }
}

5.Servlet类：

public class ShowPageServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        
        int pageIndex = 1;
        int count = 0;
        int pageSize = 10;
        PersonDao dao = new PersonDao();
        List<Person> list= new ArrayList<Person>();
        
        if(req.getParameter("pageIndex") != null){
            pageIndex = Integer.parseInt(req.getParameter("pageIndex"));;
        }
        try {
            count = dao.getCount(null);
            list = dao.findByPaging(pageIndex, pageSize, null);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        int pageCount = count/10;
        
        req.setAttribute("pageCount", pageCount);//共 页
        req.setAttribute("list", list);
        req.setAttribute("pageIndex", pageIndex);//第 页
        req.setAttribute("count", count);
        req.getRequestDispatcher("showpage.jsp").forward(req, resp);
    }
        
}

6.xml文件配置

<servlet>
    <servlet-name>page</servlet-name>
    <servlet-class>com.phome.servlet.ShowPageServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>page</servlet-name>
    <url-pattern>/page</url-pattern>
  </servlet-mapping>

7.Jsp

Index.jsp

<form action="${pageContext.request.contextPath}/page" method="post" >
           <input type="submit" value="分页显示" />
       </form>

showpage.jsp

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

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>分页管理页面</title>
    <style>
        *{
            font-size:12px;
        }
        table{
            width:100%;
            height:100%;
            border-collapse:collapse;
            border:1px solid #78C0D4;
        }
        td,th{
            border:1px solid #78C0D4;
        }
        .first-line{
            height:20px;
            background-color:#A5D5E2;
        }
    </style>
  </head>
  
  <body>
      <div style="600px;height:400px;margin-left:300px;">
        <table align="center" width="300px">
            <tr class="first-line">
                <th>
                    Id
                </th>
                <th>
                    姓名
                </th>
                <th>
                    年龄
                </th>
                <th>
                    性别
                </th>
            </tr>
            
            <c:forEach var="person" items="${list}" varStatus="s">
                <tr <c:if test="${s.index mod 2 != 0}">style="background-color:#eee"</c:if> >
                    <td>
                        ${person.id}
                    </td>
                    <td>
                        ${person.name}
                    </td>
                    <td>
                        ${person.age}
                    </td>
                    <td>
                        ${person.sex}
                    </td>
                </tr>
            </c:forEach>
        </table>
    </div>
    <div style="600px;height:400px;margin-left:500px;">
        <a href="page?pageIndex=1">首页</a>&nbsp;
        <a href="page?pageIndex=${pageIndex<=1 ? 1:pageIndex-1 }">上页</a>&nbsp;
        <a style="color:red;">第${pageIndex }页</a>&nbsp;/&nbsp;
        <a style="color:red;">共${pageCount+1 }页</a>&nbsp;
        <a href="page?pageIndex=${pageIndex>=pageCount+1 ? pageCount+1:pageIndex+1 }">下页</a>&nbsp;
        <a href="page?pageIndex=${pageCount+1 }">尾页</a>&nbsp;
        <form action="${pageContext.request.contextPath}/page">
            跳转至<input type="text" name="pageIndex" style="25px;"/>页
            <input type="submit" value="跳转" />
        </form>
    </div>
  </body>
</html>

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效果图：