JDBC实现分页查询
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在MySQL中使用关键字limit控制查询的起始位置和返回的记录数量来实现分页，limit arg1,arg2.java
示例以下：mysql
起始页index.jsp：web
<%@page import="java.net.URLDecoder"%> <%@ page language="java" import="java.util.*" import="com.home.web.dto.*" 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>起始页</title> </head> <body> <a href="FindServlet">查看全部商品信息</a> </body> </html>
查询数据的FindServlet：sql
package com.home.web.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.home.web.dao.book.BookDao;
import com.home.web.dto.Book;
/**
* Servlet implementation class AddServlet
*/
@WebServlet("/FindServlet")
public class FindServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public FindServlet() {
super();
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int curPage=1;
if(request.getParameter("page")!=null){
curPage=Integer.parseInt(request.getParameter("page"));
}
BookDao dao = new BookDao();
List<Book> list = dao.find(curPage);
request.setAttribute("list", list);
int pages;
int count = dao.findCount();
// 计算页数
if (count % Book.PAGE_SIZE == 0) {
pages = count / Book.PAGE_SIZE;
} else {
pages = count / Book.PAGE_SIZE + 1;
}
// 构建分页条
StringBuffer sb = new StringBuffer();
for (int i = 1; i <= pages; i++) {
if (i == curPage) {
sb.append("【" + i + "】");
} else {
sb.append("<a href='FindServlet?page=" + i + "'>" + i + "</a>");
}
sb.append(" ");
}
request.setAttribute("bar", sb.toString());
request.getRequestDispatcher("result.jsp").forward(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
展现页面result.jsp：数据库
<%@page import="java.sql.*"%>
<%@ page language="java" import="java.util.*" autoFlush="true"
import="com.home.web.dto.*" 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>Insert title here</title>
</head>
<body>
<table align="center" width="450" border="1">
<tr>
<td colspan="5" align="center">
<h2>全部图书信息</h2>
</td>
</tr>
<tr align="center">
<td><b>ID</b></td>
<td><b>图书名称</b></td>
<td><b>价格</b></td>
<td><b>数量</b></td>
<td><b>做者</b></td>
</tr>
<%
List<Book> list = (List<Book>) request.getAttribute("list");
if (list == null || list.size() < 1) {
out.println("没有数据！");
} else {
for (Book book : list) {
%>
<tr align="center">
<td><%=book.getId()%></td>
<td><%=book.getName()%></td>
<td><%=book.getPrice()%></td>
<td><%=book.getBookCount()%></td>
<td><%=book.getAuthor()%></td>
</tr>
<%
}
}
%>
<tr>
<td align="center" colspan="5"><%=request.getAttribute("bar")%>
</td>
</tr>
</table>
</body>
</html>
实体类Book：app
package com.home.web.dto;
public class Book {
public static final int PAGE_SIZE = 3;
private int id;
private String name;
private double price;
private int bookCount;
private String author;
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 double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public int getBookCount() {
return bookCount;
}
public void setBookCount(int bookCount) {
this.bookCount = bookCount;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
}
数据库操做类BookDao:jsp
package com.home.web.dao.book;
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 com.home.web.dto.Book;
public class BookDao {
public Connection getConnection() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/test";
conn = DriverManager.getConnection(url, "root", "123456");
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
*
* @description 分页查询数据
* @param page
* @return
*/
public List<Book> find(int page) {
List<Book> list = new ArrayList<>();
Connection conn = getConnection();
String sql = "select * from t_books order by id desc limit ?,?";
try {
PreparedStatement ps = conn.prepareStatement(sql);
ps.setInt(1, (page - 1) * Book.PAGE_SIZE);
ps.setInt(2, Book.PAGE_SIZE);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
Book book = new Book();
book.setId(rs.getInt("id"));
book.setName(rs.getString("name"));
book.setPrice(rs.getDouble("price"));
book.setBookCount(rs.getInt("bookCount"));
book.setAuthor(rs.getString("author"));
list.add(book);
}
rs.close();
ps.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
return list;
}
/**
*
* @description 查询总记录数
* @return
*/
public int findCount() {
int count = 0;
Connection conn = getConnection();
String sql = "select count(*) from t_books";
try {
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);
if (rs.next()) {
count = rs.getInt(1);
}
rs.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
return count;
}
}
效果以下：ui