模仿人人网 拖动滚动条到页面底端时加载新消息[AJAX、jQuery、web service]
当页面滚动到低端时，执行ajax方法从web service获取更多微博，并加载到页面上
GetMicroblogs.js
@H_404_20@/// <reference path="../Scripts/jquery-1.4.1-vsdoc.js" />
$(function () {
var i = 0;
$(window).bind("scroll",function (event) {
滚动条到网页头部的 高度，兼容ie,ff,chrome
var top = document.documentElement.scrollTop + document.body.scrollTop; ??????网页的高度var textheight = $(document).height();
网页高度-top-当前窗口高度 if (textheight - top - $(window).height() <= 100) {
if (i >= 25) {
return; 控制最大只能加载到100条
}
$('#divContent').css("height",$(document).height() + 400);
i++;
可以根据实际情况，获取ajax动态数据加载到 divContent中
var dataParas = '{ pageIdx:"' + i.toString() + '"}'; 这里要直接使用JOSN作为webService参数
$.ajax({
type: "POST",dataType: "json",contentType: "application/json",data: dataParas,url: "../MicroBlog.asmx/GetMicroBlogs",success: function (data) {
将获取到的JSON对象数组转换为js对象
var blogs = eval("MicroBlogs = " + data.d);
遍历微博对象数组，追加到divContent中for (var j = 0; j < 4; j++) {
$('<div>' + blogs.MicroBlogs[j].Sender + '</div>').appendTo($('#divContent'));
}
},error: function () {
alert("error occured!");
}
});
}
});
});
页面加载时引发
$(document).ready(doc_ready);
页面加载时加载前4条微博
function doc_ready() {
var jsonParas = '{ pageIdx:"0"}';
$.ajax({
type: "POST",data: jsonParas,255)">function (data) {
var blogs = eval("MicroBlogs = " + data.d);
var j = 0; j < 4; j++) {
$('<div>' + blogs.MicroBlogs[j].Sender + '</div>').appendTo($('#divContent'));
}
},error: ajax_error()
});
}
function ajax_error() {
alert("The call to webService is Failed!!!!!");
}
ScrollLoadMicroBlog.aspx :
<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage/Site.Master" AutoEventWireup="true" CodeBehind="ScrollLoadMicroBlog.aspx.cs" Inherits="MicroBlogs_WEB.拉动滚动条加载微博.ScrollLoadMicroBlog" %>
asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">
script src="../Scripts/jquery-1.4.1.js" type="text/javascript"></script="getMicroBlogs.js">
style>
#divContent div{ font-size:100px; background:#ccc;margin-top:5px}
</>
asp:Content="Content2"="MainContent"%-- 显示微博的区域 --%>
div ="height: 600px;" id="divContent">
div>
使用ajax方法从web service获得json数据：
MicroBlog.asmx :
1 using System.Runtime.Serialization;
2 using System.Web.Script.Serialization;
3
4 namespace microblog_WEB
5 {
6 /// <summary> 7 MicroBlog 的摘要说明
8 </summary>
9 [WebService(Namespace = "http://tempuri.org/")]
10 [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
11 [System.ComponentModel.ToolBoxItem(false)]
12 [System.Web.Script.Services.ScriptService]
13 public class MicroBlog : System.Web.Services.WebService
14 {
15
16 [WebMethod]
17 string HelloWorld ()
18 {
19 return Hello World";
20 }
21
22 [WebMethod]
23 string GetMicroBlogs ( uint pageIdx )
24 {
25 string jsonStr = string.Empty;
26 uint i = pageIdx * 4; i < (pageIdx * 4) + 4; i++)
27 {
28 MicroBlogModel blg = new MicroBlogModel();
29 blg.Sender = sender" + i;
30 blg.Content = content:31 jsonStr += (blg.ToJson()+,");
32 }
33 return ({ \"MicroBlogs\": [" + jsonStr.Remove(jsonStr.Length - 1) + ] }34 }
35
36 }
37
38 [Serializable]
39 class MicroBlogModel
40 {
41 private string _sender = 42
43 string Sender
44 {
45 get { return _sender; }
46 set { _sender = value; }
47 }
48 uint _senderID = 0;
49
50 uint SenderID
51 {
52 return _senderID; }
53 set { _senderID = value; }
54 }
55 string _content = 56
57 string Content
58 {
59 return _content; }
60 set { _content = value; }
61 }
62 private DateTime sendtime;
63
64 public DateTime Sendtime
65 {
66 return sendtime; }
67 set { sendtime = value; }
68 }
69
70 string ToJson ()
71 {
72 JavaScriptSerializer jsSerializer = new JavaScriptSerializer();
73 return jsSerializer.Serialize(this);
74 }
75
76 }
77 }
