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如何用jsp+mysql實現網頁的分頁查詢

發布時間:2022-02-09 16:25:54 來源:億速云 閱讀:172 作者:iii 欄目:開發技術

本篇內容介紹了“如何用jsp+mysql實現網頁的分頁查詢”的有關知識,在實際案例的操作過程中,不少人都會遇到這樣的困境,接下來就讓小編帶領大家學習一下如何處理這些情況吧!希望大家仔細閱讀,能夠學有所成!

一、實現分頁查詢的核心sql語句

(1)查詢數據庫的記錄總數的sql語句:

select count(*) from +(表名);

(2)每次查詢的記錄數的sql語句:

其中:0是搜索的索引,2是每次查找的條數。

select * from 表名 limit 0,2;

二、代碼實現

*上篇寫過這兩個類 , DBconnection類:用于獲取數據庫連接,Author對象類。這兩個類的代碼點擊連接查看。點擊鏈接查看 DBconnection類和Author對象類

(1)登錄頁面:index.jsp。

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Insert title here</title>
</head>
<body>
    <a href="AuthorListPageServlet">用戶列表分頁查詢</a>
</body>
</html>

(2)顯示頁面:userlistpage.jsp。

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>查詢頁面</title>
</head>
<body>
<table border="1">
  <tr>
    <td>編號</td>
    <td>名稱</td>
    <td>價格</td>
    <td>數量</td>
    <td>日期</td>
    <td>風格</td>
  </tr>
  <c:forEach items="${pageBean.list}" var="author">
  <tr>
    <td>${author.id}</td>
    <td>${author.name }</td>
    <td>${author.price }</td>
    <td>${author.num }</td>
    <td>${author.dates}</td>
    <td>${author.style}</td>
  </tr>
  </c:forEach>
</table>
<c:if test="${ pageBean.record>0}">
<div>
      
      <c:if test="${pageBean.currentPage <= 1}">
      <span>首頁</span>
      <span>上一頁</span>
      <a href ="AuthorListPageServlet?currPage=${pageBean.currentPage + 1 }">下一頁</a>
      <a href ="AuthorListPageServlet?currPage=${pageBean.totalPage }">尾頁</a>
      </c:if>
      
      <c:if test="${pageBean.currentPage > 1 && pageBean.currentPage < pageBean.totalPage  }">
       <a href ="AuthorListPageServlet?currPage=1">首頁</a>
      <a href ="AuthorListPageServlet?currPage=${pageBean.currentPage - 1 }">上一頁</a>
      <a href ="AuthorListPageServlet?currPage=${pageBean.currentPage + 1 }">下一頁</a>
      <a href ="AuthorListPageServlet?currPage=${pageBean.totalPage }">尾頁</a>
      </c:if>
     
     <c:if test="${ pageBean.currentPage >= pageBean.totalPage}">
      <a href ="AuthorListPageServlet?currPage=1">首頁</a>
      <a href ="AuthorListPageServlet?currPage=${pageBean.currentPage - 1 }">上一頁</a>
     <span>下一頁</span>
     <span>尾頁</span>
     </c:if>
</div>
</c:if>
</body>
</html>

(3)功能實現:AuthorDao.java。

package com.dao;

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

import com.entity.Author;

public class AuthorDao {
    
     public  Author check(String username ,int  password ) {
         
         Author obj = null ;
         try {
            DBConnection db = new DBConnection();
            //獲取數據庫連接
            Connection conn = db.getConn();
            
            String sql="select *from furnitures where name = ? and id = ?";
            
            PreparedStatement ps=conn.prepareStatement(sql);
            //設置用戶名和密碼作為參數放入sql語句
            ps.setString(1,username);
            ps.setInt(2,password);
            //執行查詢語句
            ResultSet rs = ps.executeQuery();
            //用戶名和密碼正確,查到數據  歐式風格  茶幾
            if(rs.next()) {
                obj = new Author();
                obj.setId(rs.getInt(1));
                obj.setName(rs.getString(2));
                obj.setPrice(rs.getInt(3));
                obj.setNum(rs.getInt(4));
                obj.setDates(rs.getString(5));
                obj.setStyle(rs.getString(6));
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
         return obj;
     }
     /**
      * 用戶列表信息查詢
      * @return
      */
     public List<Author> queryAuthorList(){
         Author obj = null ;
         List<Author> list = new ArrayList<Author>();
         try {
            DBConnection db = new DBConnection();
            //獲取數據庫連接
            Connection conn = db.getConn();
            
            String sql="select *from furnitures";
            
            PreparedStatement ps=conn.prepareStatement(sql);
    
            //執行查詢語句
            ResultSet rs = ps.executeQuery();
            //用戶名和密碼正確,查到數據  歐式風格  茶幾
            //循環遍歷獲取用戶信息
            while(rs.next()) {
                
                obj = new Author();
                obj.setId(rs.getInt(1));
                obj.setName(rs.getString(2));
                obj.setPrice(rs.getInt(3));
                obj.setNum(rs.getInt(4));
                obj.setDates(rs.getString(5));
                obj.setStyle(rs.getString(6));
                //將對象加入list里邊
                list.add(obj);
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
         return list;
     }
     
     
     /**
      * 查詢用戶表總記錄數
      * @return
      */
     public int queryUserListCount() {
         DBConnection db;
        try {
             db = new DBConnection();
             Connection conn = db.getConn();
             String sql = "select count(*) from furnitures";
             
             PreparedStatement ps = conn.prepareStatement(sql);
             ResultSet rs = ps.executeQuery();
             
             
             if(rs.next()) {
                 return rs.getInt(1);
             }
             
             
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
         return 0;
     }
     /**
      * 查詢用戶分頁數據
      * @param pageIndex數據起始索引
      * @param pageSize每頁顯示條數
      * @return
      */
     public List<Author>queryUserListPage(int pageIndex,int pageSize){
         
         Author obj = null;
         List<Author> list = new ArrayList<Author>();
         
         try {
            Connection conn = new DBConnection().getConn();
            String sql = "select * from furnitures limit ?,?;";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setObject(1, pageIndex);
            ps.setObject(2,pageSize);
            
            ResultSet rs = ps.executeQuery();
            //遍歷結果集獲取用戶列表數據
            
            while(rs.next()) {
                obj = new Author();
                
                obj.setId(rs.getInt(1));
                obj.setName(rs.getString(2));
                obj.setPrice(rs.getInt(3));
                obj.setNum(rs.getInt(4));
                obj.setDates(rs.getString(5));
                obj.setStyle(rs.getString(6));
                
                list.add(obj);
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
         return list;
     }
     /**
      * 用戶新增
      * @param obj
      */
     public void add(Author obj) {
        
        try {
            
            DBConnection db = new DBConnection();
            //獲取數據庫連接
            Connection conn = db.getConn();
            
            String sql="insert into furnitures values(id,?,?,?,?,?)";
            
            PreparedStatement ps=conn.prepareStatement(sql);
            ps.setObject(1, obj.getName());
            ps.setObject(2, obj.getPrice());
            ps.setObject(3, obj.getNum());
            ps.setObject(4,obj.getDates());
            ps.setObject(5, obj.getStyle());
            
            //執行sql語句
           ps.execute();
           
            
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
            
     }
     //刪除用戶
     public void del(int id) {
         try {
                
                DBConnection db = new DBConnection();
                //獲取數據庫連接
                Connection conn = db.getConn();
                
                String sql="delete from furnitures where id = ?";
                
                PreparedStatement ps=conn.prepareStatement(sql);
                
                ps.setObject(1, id);
                
                //執行sql語句
               ps.execute();
               
                
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
                
     }
    
}

(4)交互層:AuthorListPageServlet.java。

package com.servlet;

import java.io.IOException;
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 com.dao.AuthorDao;
import com.entity.Author;
import com.util.PageBean;

/**
 * Servlet implementation class AuthorListPageServlet
 */
@WebServlet("/AuthorListPageServlet")
public class AuthorListPageServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public AuthorListPageServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        int pageSize = 2;
        AuthorDao ad = new AuthorDao();
        //總記錄數
        int record = ad.queryUserListCount();
        //接收頁面傳入的頁碼
        String strPage = request.getParameter("currPage");
        int currPage = 1;//默認第一頁
        if(strPage != null) {
            currPage = Integer.parseInt(strPage);
    
        }
        
        PageBean<Author> pb = new PageBean<Author>(currPage,pageSize,record);
        //查詢某一頁的結果集
        List<Author> list = ad.queryUserListPage(pb.getPageIndex(), pageSize);
        pb.setList(list);
        request.setAttribute("pageBean", pb);
        request.getRequestDispatcher("userlistpage.jsp").forward(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

(5)工具類:PageBean.java。作用是:獲取結果集。

package com.util;

import java.util.List;

public class PageBean<T>{
    private int currentPage;//當前頁碼
    private int pageIndex;//數據起始索引
    private int pageSize;//每頁條數
    
    
    private int record;//總記錄數
    private int totalPage;//總頁數
    
    private List<T>list;//每頁顯示的結果集
    /**
     * 構造方法初始化pageIndex和totalPage
     * @param currentPage
     * @param pageIndex
     * @param pageSize
     */
    public PageBean(int currentPage,int pageSize,int record) {
        
        this.currentPage = currentPage;
        this.pageSize = pageSize;
        this.record = record;
        
        //總頁數
        if(record % pageSize == 0) {
            //整除,沒有多余的頁
            this.totalPage = record / pageSize;
            
        }
        else {
            //有多余的數據,在增加一頁
            this.totalPage = record / pageSize + 1;
        }
        
        //計算數據起始索引pageIndex
        if(currentPage < 1) {
            this.currentPage = 1;
        }
        else if(currentPage > this.totalPage) {
            this.currentPage = this.totalPage;
        }
        this.pageIndex = (this.currentPage -1)*this.pageSize;
    }
    
    public int getCurrentPage() {
        return currentPage;
    }

    public void setCurrentPage(int currentPage) {
        this.currentPage = currentPage;
    }

    public int getPageIndex() {
        return pageIndex;
    }

    public void setPageIndex(int pageIndex) {
        this.pageIndex = pageIndex;
    }

    public int getPageSize() {
        return pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getRecord() {
        return record;
    }

    public void setRecord(int record) {
        this.record = record;
    }

    public int getTotalPage() {
        return totalPage;
    }

    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }

    public List<T> getList() {
        return list;
    }

    public void setList(List<T> list) {
        this.list = list;
    }
    
}

三、運行結果

(1)首頁:

如何用jsp+mysql實現網頁的分頁查詢

(2)中間頁:

如何用jsp+mysql實現網頁的分頁查詢

(3)尾頁:

如何用jsp+mysql實現網頁的分頁查詢

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