请给出一个MVC模式下用Servlet和jsp分页的HelloWord实际的例子?
3.MVC模式下分页:
马克-to-win:像淘宝百度这样的类似网页,我们用了很多很多。基本上就 是输入查询条件以后,符合查询条件的结果可能会成千上万。我们不能一下子把所有这些结果都列出来,只能一次显示一页。当用户按下一页的时候,才会把下一页 的内容列出来。这样不至于内存崩溃。要达到这样的效果,要用到分页技术。分页技术的核心思想就是把所有的结果放在一个ArrayList的当中(在我们的 例子当中就是ArrayList ret)。马克-to-win:这个ArrayList连同相关参数比如一共有多少行(totalNumberOfRowsInDB),每页有多少行(pageSize),当 前显示是第几页(currentPageNumber),一共有多少页(totalNumberOfPages),都放在Session当中。马克-to -win:返回到jsp后,再从Session当中取出所有这些数据,把它显示出来。注意这里数据库的每行数据都对应一个RegisterRow实例。把 所有这些实例都放在ArrayList当中。如果你觉得全部把结果放在Session当中浪费空间的话,你甚至一次只放5页,当用户访问第5页的时候,你 就再一次访问数据库,把数据放在Session当中。算法由你自己定义,据情况而定。当然,为简单起见,我们的例子是把所有符合条件的数据都给取出来。
例1.3.1:
home.jsp:
<%@ page contentType="text/html; charset=GBK" %>
<html>
<form method="post" action="MarkToWinServlet">
每页 <input type="text" name="pagesize" value="2">条
第 <input type="text" name="pageno" value="3">页
查id小于 <input type="text" name="id" value="8">
<input type="submit" name="Submit" value="Submit">
</form>
<hr>
既然这是首页,像淘宝首页一样,这底下是首页的一些泛泛信息。
</html>
package com;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ServletHello1 extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("GBK");
String pageno = request.getParameter("pageno");
String pagesize = request.getParameter("pagesize");
String id = request.getParameter("id");
MyBean mb = new MyBean();
try {
mb.getData(pageno, pagesize, id);
} catch (Exception e) {
e.printStackTrace();
}
request.getSession().setAttribute("myBean", mb);
response.sendRedirect("show.jsp");
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
}
MyBean.java:
package com;
import java.sql.*;
import java.util.ArrayList;
public class MyBean {
/* 下面一大堆变量,jsp中都需要取到,所以是类变量, 非局部 */
private int totalNumberOfRowsInDB; // 数据表中总共存储了多少行
private int pageSize;
private int currentPageNumber;
private int totalNumberOfPages;
private int id;
private ArrayList ret;
public void getData(String curpage, String pagesizeS, String idS)
throws Exception {
Connection con;
/*
* MysqlConnectionPoolDataSource ds is always in the memory once it is
* created becasue it is static..
*/
con = DatabaseConn.getConnection();
if (curpage == null) {
currentPageNumber = 1; // 如果“PAGE”为NULL时将当前页面设置为1
} else {
currentPageNumber = Integer.parseInt(curpage);
if (currentPageNumber < 1) { // 如果当前页小于1,将当前页设置为1
currentPageNumber = 1;
}
}
id = Integer.parseInt(idS);
pageSize = Integer.parseInt(pagesizeS);
int i = 0;
ret = new ArrayList();
Statement stm = null;
ResultSet rs = null;
stm = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
String sql = "select * from register where id<" + id;
rs = stm.executeQuery(sql);
rs.last();
public void setAge(int age) {
this.age = age;
}
}
更多内容请见原文,文章转载自:https://blog.csdn.net/qq_44594371/article/details/103181543