分页

　　OK~~第一次来博客园扯扯淡。

　　分页其实很简单，就是在action中对数据进行切割，然后用page判断拿第几块的数据，然后将数据扔到view中显示。很简单~~有木有。

　　下面是代码：

public ActionResult Index(int? page)
        {
            //获取搜索信息
            int userId = (string.IsNullOrEmpty(Request.Params["userid"]) ? 0 : Convert.ToInt32(Request.Params["userid"]));
            string productname = string.IsNullOrEmpty(Request.Params["productname"]) ? "" : Request.Params["productname"].Trim();
            string status = string.IsNullOrEmpty(Request.Params["status"]) ? "" : Request.Params["status"].Trim();

            var orders = from x in context.PurchaseOrders
                          where x.Product.Name.Contains(productname == "" ? x.Product.Name : productname) &&
                                    x.Status == (status == "" ? x.Status : status)&&
                                    x.IsDelete == false &&
                                    x.CreateBy == (userId == 0 ? x.CreateBy : userId)
                          select x;
            ViewBag.User = context.Users.ToList();
            return View(orders.OrderByDescending(x => x.CreateAt).ToPagedList(page ?? 1, 30));
        }

 

　　其中int? page是指这个page可为null的int类型。如果url是www.xxx.com/home/index?page=12,就是说第12页。后面的page??1,30是指page为空时传入1，不为空时传入page的值，后面的30是ToPagedList的第二个参数，下面会给出ToPagedList的代码。还有就是说这个数据在分页前要排序一下，不然会出错地喽。

　　下面是ToPagedList的代码：

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Collections.Generic;
using System.Text;
using System.Web.Mvc;
using System.Text.RegularExpressions;

namespace Purchase.Helpers
{
    public class PagedList<T> : List<T> {

        public int CurrentPageIndex { get; set; }
        public int PageSize { get; set; }
        public int TotalItemCount { get; set; }
        public int TotalPageCount{get; private set;}
        public int StartRecordIndex{get; private set;}
        public int EndRecordIndex{get; private set;}

        public PagedList(IList<T> items,int pageIndex,int pageSize)
        {
            PageSize = pageSize;
            TotalItemCount = items.Count;
            TotalPageCount = (int)Math.Ceiling(TotalItemCount / (double)PageSize);
            CurrentPageIndex = pageIndex;
            StartRecordIndex=(CurrentPageIndex - 1) * PageSize + 1;
            EndRecordIndex = TotalItemCount > pageIndex * pageSize ? pageIndex * pageSize : TotalItemCount;
            for (int i = StartRecordIndex-1; i < EndRecordIndex;i++ )
            {
                Add(items[i]); 
            }
        }

        public PagedList(IEnumerable<T> items, int pageIndex, int pageSize, int totalItemCount)
        {
            AddRange(items);
            TotalItemCount = totalItemCount;
            TotalPageCount = (int)Math.Ceiling(totalItemCount / (double)pageSize);
            CurrentPageIndex = pageIndex;
            PageSize = pageSize;
            StartRecordIndex = (pageIndex - 1) * pageSize + 1;
            EndRecordIndex = TotalItemCount > pageIndex * pageSize ? pageIndex * pageSize : totalItemCount;
        }
    }

    public static class PageLinqExtensions
    {
        public static PagedList<T> ToPagedList<T>(this IQueryable<T> allItems,int pageIndex,int pageSize)
        {
            if (pageIndex < 1)
                pageIndex = 1;
            var itemIndex = (pageIndex - 1) * pageSize;
            var pageOfItems = allItems.Skip(itemIndex).Take(pageSize);
            var totalItemCount = allItems.Count();
            return new PagedList<T>(pageOfItems, pageIndex, pageSize, totalItemCount);
        }
    }



    public static class PagerHelper
    {

        public static string Pager(this HtmlHelper helper, int pageSize, int currentPageIndex, int totalPages, int totalItemCount)
        {
            bool hasPreviousPage = (currentPageIndex > 1);
            bool hasNextPage = (currentPageIndex  < totalPages);

            StringBuilder sb = new StringBuilder();
            string reqUrl = helper.ViewContext.HttpContext.Request.RawUrl;
            string link = "";

            Regex re = new Regex(@"page=(\d+)|page=", RegexOptions.IgnoreCase);

            MatchCollection results = re.Matches(reqUrl);

            if (results.Count > 0)
            {
                link = reqUrl.Replace(results[0].ToString(), "page={0}");
            }
            else if (reqUrl.IndexOf("?") < 0)
            {
                link = reqUrl + "?page={0}";
            }
            else
            {
                link = reqUrl + "&page={0}";
            }

            if (totalItemCount > pageSize)
            {
                sb.Append("<div class=\"pager\">");

                if (hasPreviousPage)
                {
                    sb.Append("<a href=\"" + string.Format(link,(currentPageIndex -1).ToString()) + "\"><img src='/images/left_arrow.gif' alt='上一页' title='上一页' /> 上一页</a>");
                }

                int beginPage = currentPageIndex - 2,endPage = currentPageIndex + 2;

                beginPage = beginPage<1?1:beginPage;
                endPage = endPage > totalPages?totalPages:endPage;

                if (beginPage >= 2)
                {
                    sb.Append("<a href=\"?"+ string.Format(link,"1") +"\">1</a>");
                    if(beginPage >2)
                        sb.Append("...");
                }



                for (int i = beginPage; i <= endPage; i++)
                {
                    if (i == currentPageIndex)
                        sb.Append("<span>").Append(i.ToString()).Append("</span>");
                    else
                        sb.Append("<a href=\"" + string.Format(link,i) + "\">" + i + "</a>");
                }

                if (endPage <= totalPages -1)
                {
                    if(endPage < totalPages -1)
                        sb.Append("...");
                    sb.Append("<a href=\"" + string.Format(link, totalPages) + "\">" + totalPages + "</a>");
                }

                if (hasNextPage)
                {
                    sb.Append("<a href=\"" + string.Format(link, (currentPageIndex + 1).ToString()) + "\">下一页 <img src='/images/right_arrow.gif' alt='下一页' title='下一页' /></a>");
                }

                sb.Append("</div>");
            }

            return sb.ToString();
        }

        public static string Pager<T>(this HtmlHelper helper, PagedList<T> pagedList)
        {
            if (pagedList == null)
                return "";
            return Pager(helper, pagedList.PageSize, pagedList.CurrentPageIndex, pagedList.TotalPageCount, pagedList.TotalItemCount);
        }

    }
}

 

　　记得把这个namespace换成自已的，不要用我的空间名。还有在controllers中引入这个空间。不要说你不会引用,using~~,you know~~。引入这个空间入就可以用ToPagedList了呦。

　　还有个问题是在view中怎么获取这个模型呢。

　　

@model PagedList<PurchaseOrder>
@using Purchase.Models
@using Purchase.Helpers

　　直接在view的头部写入这个 当然这个helpers类要写喽 如果你之前的空间名改了的话就写你的空间名喽。模型就是PagedList类型，别给写错了。

　　下面是显示第几页的html

<h3 style="float:right;margin:20px;">@Html.Raw(Html.Pager(Model))</h3>

　　OK了。这个h3标签你可以自已改。