Servlet+mysql实现分页技术
先让数据库中的数据显示出来
数据库信息：
然后通过Servlet，使数据库中的信息在浏览器中通过表格的形式显示出来：
package com.page.one;
import javafx.print.Printer;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Page extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
request.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
try{
//1.注册驱动
Class.forName("com.mysql.jdbc.Driver");
//2.获得数据库连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","123456");
//3.创建句柄
Statement stmt = conn.createStatement();
//4.执行SQL语句
ResultSet rs = stmt.executeQuery("SELECT * FROM users");
//5.处理执行结果
out.println("");
out.println("ID 用户名 电子邮件 等级 "+rs.getInt("id")+" "+
rs.getString("username")+" "+
rs.getString("email")+" "+
rs.getInt("grade")+"
");
}catch (SQLException e){
e.printStackTrace();
}catch (ClassNotFoundException e){
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}
显示内容：
添加分页
定义分页变量：
1. pagenow:表示第几页 (由用户来决定， 因此变化)
2. pageSize：每页显示多少条记录 (有程序制定，也可以让用户来定制)
3. pageCount: 表示共有多少页 (这是计算出来的)
4. rowCount: 共有多少条记录 (通过查询数据库得到的)
先设置变量：
//设置总页数变量
int pageCount=1;
//设置总行数变量
int rowCount=1;
//设置目前所在页面
int pageNow=1;
//设置每页信息行数
int pageSize=4;
求出信息总行数
//执行SQL语句，来确定总信息数量
ResultSet rs2 = stmt.executeQuery("SELECT count(*) FROM users");
rs2.next();
rowCount = rs2.getInt(1);
求出总页数
//计算PageCount
pageCount = rowCount%pageSize==0 ? rowCount/pageSize : rowCount/pageSize+1;
执行语句显示本页面的信息
ResultSet rs = stmt.executeQuery("SELECT * FROM users ORDER BY ID LIMIT "+(pageNow-1)*pageSize+","+pageSize);
在表下方显示页面
for(int i = 1; i <= pageCount; i++){
out.println("<"+i+">");
}
接收超链接所提交的页面选项
String spageNow = request.getParameter("pageNow");
if(spageNow != null){
pageNow = Integer.parseInt(spageNow);
}
因为没有选的时候接收到的是空值，直接不需要转换，使用初定义就行了。
page2.java
public class Page extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
request.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
//设置总页数变量
int pageCount=1;
//设置总行数变量
int rowCount=1;
//设置目前所在页面
int pageNow=1;
//设置每页信息行数
int pageSize=4;
String spageNow = request.getParameter("pageNow");
if(spageNow != null){
pageNow = Integer.parseInt(spageNow);
}
try{
//1.注册驱动
Class.forName("com.mysql.jdbc.Driver");
//2.获得数据库连 接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","123456");
//3.创建句柄
Statement stmt = conn.createStatement();
//执行SQL语句，来确定总信息数量
ResultSet rs2 = stmt.executeQuery("SELECT count(*) FROM users");
rs2.next();
rowCount = rs2.getInt(1);
out.println("rowCount = "+rowCount);
//计算PageCount
pageCount = rowCount%pageSize==0 ? rowCount/pageSize : rowCount/pageSize+1;
//执行SQL语句
ResultSet rs = stmt.executeQuery("SELECT * FROM users ORDER BY ID LIMIT "+(pageNow-1)*pageSize+","+pageSize);
//处理执行结果
out.println("");
out.println("ID 用户名 电子邮件 等级 "+rs.getInt("id")+" "+
rs.getString("username")+" "+
rs.getString("email")+" "+
rs.getInt("grade")+"
");
for(int i = 1; i <= pageCount; i++){
out.println("<"+i+">");
}
}catch (SQLException e){
e.printStackTrace();
}catch (ClassNotFoundException e){
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}
结果显示
当然也可以完善一些，添加上上一页与下一页，以及跳转页数，但是要注意上一页到第一页与下一页到最后一页的情况，以及跳转时输入不在范围内的情况：
直接上代码吧。。
上下一页：
//当到第一页时就没有上一页这个选项了
if(pageNow!=1){
out.println("上一页");
}
for(int i = 1; i <= pageCount; i++){
out.println("<"+i+">");
}
//当到最后一页时就没有下一页这个选项了
if(pageNow!=pageCount){
out.println("下一页");
}
显示分页信息：
//显示分页信息
out.println(" 当前页:"+pageNow+"| 总页数:"+pageCount);
跳转：
out.println("
");
out.println("跳转到第 ");
JavaScript语言来实现跳转：
//添加JavaScript代码
out.println("");
注意超出范围的情况：
String spageNow = request.getParameter("pageNow");
if(spageNow!=null){
int temp = Integer.parseInt(spageNow);
if(temp<=pageCount&&temp>=1){
pageNow = temp;
}else{
out.println("");
}
}
page.java
public class Page extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
request.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
//添加JavaScript代码
out.println("");
//设置总页数变量
int pageCount=1;
//设置总行数变量
int rowCount=1;
//设置目前所在页面
int pageNow=1;
//设置每页信息行数
int pageSize=4;
try{
//1.注册驱动
Class.forName("com.mysql.jdbc.Driver");
//2.获得数据库连 接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","123456");
//3.创建句柄
Statement stmt = conn.createStatement();
//执行SQL语句，来确定总信息数量
ResultSet rs2 = stmt.executeQuery("SELECT count(*) FROM users");
rs2.next();
rowCount = rs2.getInt(1);
out.println("rowCount = "+rowCount);
//计算PageCount
pageCount = rowCount%pageSize==0 ? rowCount/pageSize : rowCount/pageSize+1;
String spageNow = request.getParameter("pageNow");
if(spageNow!=null){
int temp = Integer.parseInt(spageNow);
if(temp<=pageCount&&temp>=1){
pageNow = temp;
}else{
out.println("");
}
}
//执行SQL语句
ResultSet rs = stmt.executeQuery("SELECT * FROM users ORDER BY ID LIMIT "+(pageNow-1)*pageSize+","+pageSize);
//处理执行结果
out.println("");
out.println("ID 用户名 电子邮件 等级 "+rs.getInt("id")+" "+
rs.getString("username")+" "+
rs.getString("email")+" "+
rs.getInt("grade")+"
");
//当到第一页时就没有上一页这个选项了
if(pageNow!=1){
out.println("上一页");
}
for(int i = 1; i <= pageCount; i++){
out.println("<"+i+">");
}
//当到最后一页时就没有下一页这个选项了
if(pageNow!=pageCount){
out.println("下一页");
}
//显示分页信息
out.println(" 当前页:"+pageNow+"| 总页数:"+pageCount);
out.println("
");
out.println("跳转到第 ");
}catch (SQLException e){
e.printStackTrace();
}catch (ClassNotFoundException e){
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}
结果：