下拉自动刷新数据

当有多条信息需要在前端展示的时候，通常的做法是做成翻页列表的形式，下拉自动刷新是翻页显示的一种，但是相较于传统的方式要更加人性化，所以今天就实现了一下下拉自动刷新的翻页形式。

 直接上代码：

<%@page import="java.util.List"%> <%@page import="java.util.ArrayList"%> <%@page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

后端处理servlet:

package com.js.test; import java.io.IOException; import java.io.PrintWriter; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import javax.servlet.ServletContext; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import net.sf.json.JSONObject; public class NewsList extends HttpServlet implements ServletContextListener{ private static final long serialVersionUID = 1L; @Override public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } @Override public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String str=request.getServletPath(); int index=str.lastIndexOf("/"); int end=str.lastIndexOf("."); String methodname=str.substring(index+1, end); Class cla=this.getClass(); Method[] method=cla.getMethods(); for(Method m:method) { if(m.getName().equals(methodname)) { try { m.invoke(this, request,response); } catch (Exception e) { System.out.println("调用错误"); } } } } public void updatemessage(HttpServletRequest request,HttpServletResponse response) throws IOException { int currentpage=Integer.parseInt(request.getParameter("currentpage")); int start=currentpage*100; List page_list=new ArrayList(); Map> info=new HashMap>(); @SuppressWarnings("unchecked") List message=(List) request.getServletContext().getAttribute("message"); if(message==null) { page_list.add("获取数据失败"); }else if(currentpage==10){ page_list.add("没有更多数据啦"); }else { page_list=message.subList(start, start+100); } info.put("message", page_list); JSONObject array=JSONObject.fromMap(info); response.setContentType("application/json"); response.setCharacterEncoding("utf-8"); PrintWriter out= response.getWriter(); out.print(array); out.flush(); }      public void Ready_message(ServletContext application) { List news=new ArrayList(); for(int i=0;i<1000;i++) { String str="这是第"+i+"条信息"; news.add(str); } application.setAttribute("message", news); } @Override public void contextDestroyed(ServletContextEvent arg0) { System.out.println("应用关闭"); } @Override public void contextInitialized(ServletContextEvent arg0) { Ready_message(arg0.getServletContext()); System.out.println("应用创建完成"); } }

由于没有从数据库中查询数据，所以这儿在应用启动的时候，先创建了一下数据，后面每次的翻页请求都从这些数据中获取。