JSP+Servlet+JDBC实现数据分页
环境
MyEclipse 8.6 + MySQL 5.1 + MySQL命令行工具+ JDK 1.6
问题
JSP+Servlet+JDBC实现分页
解决
第一步 创建数据库
以下为数据库导出脚本。
test.sql
-- MySQL dump 10.13 Distrib 5.1.43, for Win32 (ia32) -- -- Host: localhost Database: test -- ------------------------------------------------------ -- Server version 5.1.43-community /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */; /*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */; /*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */; /*!40101 SET NAMES utf8 */; /*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */; /*!40103 SET TIME_ZONE='+00:00' */; /*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */; /*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */; /*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */; /*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */; -- -- Table structure for table `test` -- DROP TABLE IF EXISTS `test`; /*!40101 SET @saved_cs_client = @@character_set_client */; /*!40101 SET character_set_client = utf8 */; CREATE TABLE `test` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(20) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=98 DEFAULT CHARSET=gbk; /*!40101 SET character_set_client = @saved_cs_client */; -- -- Dumping data for table `test` -- LOCK TABLES `test` WRITE; /*!40000 ALTER TABLE `test` DISABLE KEYS */; INSERT INTO `test` VALUES (1,'test1'),(2,'test2'),(3,'test3'),(4,'test4'),(5,'test5'),(6,'test6'),(7,'test7'),(8,'test8'),(9,'test9'),(10,'test10'),(11,'test1'),(12,'test2'),(13,'test3'),(14,'test4'),(15,'test5'),(16,'test6'),(17,'test7'),(18,'test8'),(19,'test9'),(20,'test10'),(26,'test1'),(27,'test2'),(28,'test3'),(29,'test4'),(30,'test5'),(31,'test6'),(32,'test7'),(33,'test8'),(34,'test9'),(35,'test10'),(36,'test1'),(37,'test2'),(38,'test3'),(39,'test4'),(40,'test5'),(41,'test6'),(42,'test7'),(43,'test8'),(44,'test9'),(45,'test10'),(57,'test1'),(58,'test2'),(59,'test3'),(60,'test4'),(61,'test5'),(62,'test6'),(63,'test7'),(64,'test8'),(65,'test9'),(66,'test10'),(67,'test1'),(68,'test2'),(69,'test3'),(70,'test4'),(71,'test5'),(72,'test6'),(73,'test7'),(74,'test8'),(75,'test9'),(76,'test10'),(77,'test1'),(78,'test2'),(79,'test3'),(80,'test4'),(81,'test5'),(82,'test6'),(83,'test7'),(84,'test8'),(85,'test9'),(86,'test10'),(87,'test1'),(88,'test2'),(89,'test3'),(90,'test4'),(91,'test5'),(92,'test6'),(93,'test7'),(94,'test8'),(95,'test9'),(96,'test10'),(97,'900'); /*!40000 ALTER TABLE `test` ENABLE KEYS */; UNLOCK TABLES; /*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */; /*!40101 SET SQL_MODE=@OLD_SQL_MODE */; /*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */; /*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */; /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */; /*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */; /*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */; /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */; -- Dump completed on 2013-01-22 11:17:45
第二步 封装实体类
Test.java
package com.wgb.bean;
public class Test {
private int id;
private String name;
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;
}
}
第三步 编写数据库连接工具类
ConnDB.java
package com.wgb.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* 类名：ConnDB
* 功能：连接数据库的类
* 开发日期：2012年5月21日
* 修复日期：2012年6月9日16:44:01 2012年6月14日20:26:25
* 原因：修改注释 换另一种方式连接数据库
* @since JDK 1.6
* @author Wentasy
* @version 1.0
*/
public class ConnDB {
//数据库连接对象
private static Connection conn = null;
//连接数据库驱动名
private static final String DRIVER_NAME = "com.mysql.jdbc.Driver";
//连接数据库URL
private static final String URL = "jdbc:mysql://localhost/test?useUnicode=true&characterEncoding=UTF-8";
//数据库用户名
private static final String USER_NAME = "root";
//用户密码
private static final String PASSWORD = "root";
/**
* 得到连接
* @return 连接对象
*/
public static Connection getConn(){
try {
Class.forName(DRIVER_NAME);
conn = DriverManager.getConnection(URL, USER_NAME, PASSWORD);
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
* 关闭结果集对象
* @param rs 结果集
* @throws SQLException
*/
public static void close(ResultSet rs) throws SQLException{
if(rs != null){
rs.close();
rs = null;
}
}
/**
* 关闭PreparedStatement对象
* @param pstmt 处理数据的对象
* @throws SQLException
*/
public static void close(PreparedStatement pstmt) throws SQLException{
if(pstmt != null){
pstmt.close();
pstmt = null;
}
}
/**
* 关闭连接对象
* @param conn 连接对象
* @throws SQLException
*/
public static void close(Connection conn) throws SQLException{
if(conn != null){
conn.close();
conn = null;
}
}
}
第四步 编写Servlet并在web.xml中注册
UserAction.java
package com.test.servlet;
import java.io.IOException;
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 javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.wgb.bean.Test;
import com.wgb.util.ConnDB;
public class UserAction extends HttpServlet {
private static final int DATA_PER_PAGE = 5;
/**
* Constructor of the object.
*/
public UserAction() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String cur = (String)request.getParameter("cur");
List<Test> list = new ArrayList<Test>();
list = new UserAction().getAllData(Integer.parseInt(cur));
int totalPage = new UserAction().getTotalPage();
request.setAttribute("tests", list);
request.setAttribute("totalPage", totalPage);
RequestDispatcher rd = request.getRequestDispatcher("test_list.jsp");
rd.forward(request, response);
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
public int getTotalPage(){
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
String sql = "";
int count = 0;
try {
sql = "select count(*) from test";
conn = ConnDB.getConn();
pstmt = conn.prepareStatement(sql);
rs = pstmt.executeQuery();
while(rs.next()){
count = rs.getInt(1);
}
count = (int)Math.ceil((count + 1.0 - 1.0) / DATA_PER_PAGE);
} catch (Exception e) {
e.printStackTrace();
}finally{
try {
ConnDB.close(rs);
ConnDB.close(pstmt);
ConnDB.close(conn);
} catch (SQLException e) {
e.printStackTrace();
}
}
return count;
}
public List<Test> getAllData(int cur){
List<Test> list = new ArrayList<Test>();
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
String sql = "";
try {
sql = "select * from test where 1 limit ?,?";
conn = ConnDB.getConn();
pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, (cur - 1) * DATA_PER_PAGE);
pstmt.setInt(2, DATA_PER_PAGE);
rs = pstmt.executeQuery();
while(rs.next()){
Test test = new Test();
int id = rs.getInt(1);
String name = rs.getString(2);
test.setId(id);
test.setName(name);
list.add(test);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
try {
ConnDB.close(rs);
ConnDB.close(pstmt);
ConnDB.close(conn);
} catch (SQLException e) {
e.printStackTrace();
}
}
return list;
}
public static void main(String[] args) {
System.out.println(new UserAction().getTotalPage());
List<Test> list = new ArrayList<Test>();
list = new UserAction().getAllData(3);
for (Test test : list) {
System.out.println(test.getName());
}
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>UserAction</servlet-name>
<servlet-class>com.test.servlet.UserAction</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UserAction</servlet-name>
<url-pattern>/UserAction</url-pattern>
</servlet-mapping>
</web-app>
因测试，此处把分页要用到的方法写到了Servlet里。MySQL分页无非用到limit关键字，需要当前是多少页，总共的页数和每页显示的页数。当前是多少页可以由页面传递，总共的页数可以有数据库的记录数除以每页显示的页数得到，每页显示的页数此处固定。所以getTotalPage方法用于获得总页数，getAllData根据当前的页数获得数据。MySQL分页参考本文：http://blog.csdn.net/wentasy/article/details/8200512
第五步 编写显示页面
test_list.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'test_list.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<ul>
<c:forEach items="${requestScope.tests}" var="p">
<li>用户名：${p.name}</li>
</c:forEach>
</ul>
<c:if test="${param.cur == 1}">
<a>首页</a>
<a>上一页</a>
</c:if>
<c:if test="${param.cur != 1}">
<a href="UserAction?cur=1">首页</a>
<a href="UserAction?cur=${param.cur - 1}">上一页</a>
</c:if>
<c:if test="${param.cur == requestScope.totalPage}">
<a>下一页</a>
<a>尾页</a>
</c:if>
<c:if test="${param.cur != requestScope.totalPage}">
<a href="UserAction?cur=${param.cur + 1}">下一页</a>
<a href="UserAction?cur=${requestScope.totalPage}">尾页</a>
</c:if>
<p>
当前第${param.cur}页 总共${requestScope.totalPage}页
</p>
</body>
</html>
第六步 测试并调试程序
访问URL：http://localhost:8088/JSP/UserAction?cur=1
参考资料
Mysql导出表结构及表数据mysqldump用法
http://www.cnblogs.com/yuanyouqi/archive/2010/04/28/1722738.html
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