概述
先看效果:
本人数据库:数据库名bookclass, 列名有:BookClassID,BookClassMC。请大家修改对应的数据库
下面开始教程:(项目名:Paging)
第一步:
1.在pom.xml中加入依赖:
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.22</version>
</dependency>
2.写一个实体类entity 封装定义的要查询的字段:
package com.sve.dao;
public class entity {
public static final int PAGE_SIZE = 5;//每页显示的条数
private int bookid;
private String boookname;
public int getBookid() {
return bookid;
}
public void setBookid(int bookid) {
this.bookid = bookid;
}
public String getBoookname() {
return boookname;
}
public void setBoookname(String boookname) {
this.boookname = boookname;
}
}
第二步:
写一个dao类 PagDao:
package com.sve.dao;
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;
public class PagDao {
public static void main(String [] args) throws SQLException {
List<entity> listentitys = new PagDao().find(1);
}
public Connection getConnection() throws SQLException {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306";
String username = "root";
String password = "******";
conn = DriverManager.getConnection(url,username,password);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}
public List<entity> find(int page) throws SQLException{
List<entity> list = new ArrayList<entity>();
Connection conn = getConnection();
String sql = "select * from library.bookclass order by BookClassID asc limit ?,?";
try {
PreparedStatement ps = conn.prepareStatement(sql);
ps.setInt(1, (page-1)*entity.PAGE_SIZE);
ps.setInt(2, entity.PAGE_SIZE);
ResultSet rs = ps.executeQuery();
while(rs.next()) {
entity e = new entity();
e.setBookid(rs.getInt("BookClassID"));
e.setBoookname(rs.getString("BookClassMC"));
list.add(e);
}
rs.close();
ps.close();
conn.close();
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
return list;
}
public int findCount() throws SQLException {
int count = 0;
Connection conn = getConnection();
String sql = "select count(*) from library.bookclass";
Statement sm = (Statement)conn.createStatement();
ResultSet rs = sm.executeQuery(sql);
if(rs.next()) {
count = rs.getInt(1);
}
rs.close();
conn.close();
return count;
}
}
第三步:
写一个servlet类:
public class PagServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public PagServlet() {
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
//当前页
int currPage = 1;
//判断页面是否有效
if(request.getParameter("page") != null) {
currPage = Integer.parseInt(request.getParameter("page"));
}
PagDao dao = new PagDao();
try {
//查询所有书籍
List<entity> list = dao.find(currPage);
request.setAttribute("list", list);
//总页数
int pages;
//总记录数
int count = dao.findCount();
//总页数
if(count % entity.PAGE_SIZE == 0) {
pages = count / entity.PAGE_SIZE;
}else {
pages = count / entity.PAGE_SIZE+1;
}
StringBuffer sb = new StringBuffer();
//
for(int i = 1;i <= pages;i++) {
//是否当前页
if(i==currPage) {
//构建分页
sb.append("【"+i+"】");
}else {
sb.append("<a href='PagServlet?page="+i+"'>"+i+"</a>");
}
sb.append(" ");
}
request.setAttribute("bar", sb.toString());
request.getRequestDispatcher("entity_list.jsp").forward(request, response);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* @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);
}
第四步:
新建一个index.jsp (模仿功能)
<%@ 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>Insert title here</title>
</head>
<body>
<a href="PagServlet">查看所有书籍</a>
</body>
</html>
第五步:
1.新建一个entity_list.jsp 显示数据页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.util.List,com.sve.dao.*" %>
<!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>所有书籍</title>
<style type="text/css">
td{font-size: 12px;}
h2{margin: 0px}
</style>
</head>
<body>
<table align="center" width="300" border="1" height="180" bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1">
<tr bgcolor="white">
<td align="center" colspan="5">
<h2>所有商品信息</h2>
</td>
</tr>
<tr align="center" bgcolor="#e1ffc1" >
<td><b>ID</b></td>
<td><b>书籍名称</b></td>
</tr>
<%
List<entity> list = (List<entity>)request.getAttribute("list");
for(entity e : list){
%>
<tr align="center" bgcolor="white">
<td><%=e.getBookid()%></td>
<td><%=e.getBoookname()%></td>
</tr>
<%} %>
<tr>
<td align="center" colspan="2" bgcolor="white">
<%=request.getAttribute("bar")%>
</td>
</tr>
</table>
</body>
</html>
2.web.xml
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Application</display-name>
<servlet>
<servlet-name>PagServlet</servlet-name>
<display-name>PagServlet</display-name>
<description></description>
<servlet-class>com.sve.servlet.PagServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>PagServlet</servlet-name>
<url-pattern>/PagServlet</url-pattern>
</servlet-mapping>
</web-app>
最后:http://localhost:8080/Paging/index.jsp
最后
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