[转载]ASP.NET MVC 3 开发的20个秘诀（十七）[20 Recipes for Programming MVC 3]：卷帘式分页加载

@model IEnumerable<MvcApplication4.Models.BookComment>
@{
    ViewBag.Title = "Home Page";
}
<h2>@ViewBag.Message</h2>
<p>
    To learn more about ASP.NET MVC visit
    <a href="http://asp.net/mvc"
    title="ASP.NET MVC Website">
    http://asp.net/mvc </a>.
</p>
<script type="text/javascript">
    var lastY = 0;
    var currentY = 0;
    var page = 1;
    var maxPages = @ViewBag.maxPages;
    $(window).scroll(function () {
        if (page < maxPages) {
            currentY = $(window).scrollTop();
            if (currentY - lastY > 200 * (page - 1)) {
                lastY = currentY;
                page++;
                $.get('CommentFeed/Comments?page=' + page,
                    function(data) {
                        $('#comments').append(data);
                });
            }
        }
    });
</script>
<div id="comments">
    <h2>Recent Comments</h2>
    @Html.Partial("../CommentFeed/Comments", Model)

</div>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Globalization;
using System.Data.Entity;
using MvcApplication4.Models;
namespace MvcApplication4.Controllers
{
    public class HomeController : Controller
    {
        private BookDBContext db = new BookDBContext();
        public ActionResult Index()
        {
            ViewBag.Message = "Welcome to ASP.NET MVC!";
            
            // Get our recent comments
            var bookcomments = db.BookComments.Include(
                b => b.Book).OrderByDescending(b => b.Created).
                    Take(3);
            var count = db.BookComments.Count();
            ViewBag.maxPages = count / 3 + 1;
            return View(bookcomments);
        }
        ...
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using MvcApplication4.Models;
using System.Data.Entity;

namespace MvcApplication4.Controllers
{
    public class CommentFeedController : AsyncController
    {
        private BookDBContext db = new BookDBContext();
        public void CommentsAsync(int page)
        {
            AsyncManager.OutstandingOperations.Increment();
            
            AsyncManager.Sync(() =>
            {
                var bookcomments = db.BookComments.Include(
                    b => b.Book).OrderByDescending(b =>
                        b.Created).Skip(page * 3).Take(3);
                AsyncManager.Parameters["bookcomments"] =
                    bookcomments;
                AsyncManager.OutstandingOperations.Decrement();
            });
        }
        
        public ActionResult CommentsCompleted(
            IEnumerable<BookComment> bookcomments)
        {
            return PartialView(bookcomments);
        }
    }
}

@model IEnumerable<MvcApplication4.Models.BookComment>
@foreach (var item in Model) {
    <h3><a href="@Url.Action("Details", "Books", new {
            ID=item.Book.ID } )">
        @Html.DisplayFor(modelItem => item.Book.Title)
    </a></h3>
    <h4>Comment Posted: @Html.DisplayFor(
        modelItem => item.Created)</h4>
    <p>@MvcHtmlString.Create(Html.Encode(item.Comment).Replace(
        Environment.NewLine, "<br />"))</p>

}