CommunityServer2.0分页控件的优化

记得去年NetFocus在群上说CommunityServer2.0的分页控件存在性能问题，当时没有留意，想不到最近就被我就碰上了，拿Pager类来说，出现问题的代码如下：

        void AddPageLinks()
        {
            // First add the lower page buttons
            //
            //CalculateTotalPages方法是在计算总页数
            pagingHyperLinks = new HyperLink[CalculateTotalPages()];

            // Create the buttons and add them to
            // the Controls collection
            //
            for (int i = 0; i < pagingHyperLinks.Length; i++)
            {
                pagingHyperLinks[i] = new HyperLink();
                pagingHyperLinks[i].EnableViewState = false;
                pagingHyperLinks[i].Text = (i + 1).ToString();
                pagingHyperLinks[i].NavigateUrl = CreatePagerURL((i + 1).ToString());
                Controls.Add(pagingHyperLinks[i]);
            }
        }

从代码中可以看出，程序直接实例化总页数多个的HyperLink，这样如果总页数过多时，必然会导致内存溢出。
可惜当时没有好好听netfocus说，没有记下他的解决方案，只好自己想就去来实现。
我采用的是对原代码影响最小的方式，只要改变原来的两个方法即可，解决的方法如下：
修改AddPageLinks方法：

        void AddPageLinks()
        {
            int totalPages = CalculateTotalPages();
            int lowerBound = 0;
            int upperBound = totalPages;
            if (totalPages > 5)
            {
                lowerBound = (PageIndex - 2);
                upperBound = (PageIndex + 3);

                if (lowerBound <= 0)
                    lowerBound = 0;
                if (PageIndex == 0 || PageIndex == 1)
                {
                    upperBound = 5;
                }
                else if (PageIndex < (totalPages - 2))
                {
                    upperBound = PageIndex + 3;
                }
                else if (PageIndex == (totalPages - 2))
                {
                    lowerBound = totalPages - 5;
                    upperBound = totalPages;
                }
                else if (PageIndex == (totalPages - 1))
                {
                    lowerBound = totalPages - 5;
                    upperBound = totalPages;
                }
            }
            pagingHyperLinks = new HyperLink[upperBound - lowerBound];
            for (int i = 0; i < upperBound - lowerBound; i++)
            {
                pagingHyperLinks[i] = new HyperLink();
                pagingHyperLinks[i].EnableViewState = false;
                pagingHyperLinks[i].Text = (i + lowerBound + 1).ToString();
                pagingHyperLinks[i].NavigateUrl = CreatePagerURL((i + 1 + lowerBound).ToString());
                pagingHyperLinks[i].CssClass = "OtherPage";
                Controls.Add(pagingHyperLinks[i]);
            }
        }

修改RenderButtonRange方法：

        void RenderButtonRange(int start, int end, HtmlTextWriter writer)
        {
            for (int i = 0; i < end - start; i++)
            {
                // Are we working with the selected index?
                //
                int realpage = i + start;
                if (PageIndex == realpage)
                {
                    // Render different output
                    Literal l = new Literal();
                    l.Text = "<span class=""currentPage"">[" + (realpage + 1).ToString() + "]</span>";
                    l.RenderControl(writer);
                }
                else
                {
                    pagingHyperLinks[i].RenderControl(writer);
                }
                if (realpage < (end - 1))
                    writer.Write(" ");
            }
        }