访问过的最后五页 Cookie

Question

所以，我有一系列产品页面，我想做的只是将最近查看的 5 个产品存储在 cookie 中，以便可以将其显示为网站历史记录。我遇到的问题不是将五个初始项目添加到 cookie 中，而是当他们查看 6、7 或 10 个项目时。有没有人对如何解决这个问题有任何真正体面的建议？

目前我有这个有缺陷的逻辑（为简洁起见，我已经替换了 cookie 名称 (xxx)）；

Dim i As Integer = 0
        Dim productcount As Integer = 0

        If HttpContext.Current.Request.Cookies("xxx") Is Nothing Then
            Dim gingernuts As New HttpCookie("xxx")
            gingernuts.Values("productcount") = 0
            gingernuts.Expires = DateTime.Now.AddDays(365)
            HttpContext.Current.Response.Cookies.Add(gingernuts)
        End If

        productcount = HttpContext.Current.Request.Cookies("xxx")("productcount")

        For i = 0 To productcount
            If HttpContext.Current.Request.Cookies("xxx")("product" & i & "") = "" Then
                HttpContext.Current.Response.Cookies("xxx")("product" & i & "") = Request.QueryString("id")
            Else
                HttpContext.Current.Response.Cookies("xxx")("product" & i & "") = HttpContext.Current.Request.Cookies("xxx")("product" & i & "")
            End If
        Next

        If productcount = 5 Then
            HttpContext.Current.Response.Cookies("xxx")("productcount") = 5
            HttpContext.Current.Response.Cookies("xxx")("product0") = ""
        Else
            HttpContext.Current.Response.Cookies("xxx")("productcount") = productcount + 1
        End If

欢迎和赞赏建议和批评。

克里斯

Answer 1

只需使用一个简单的 cookie 值，即最近查看的产品 ID 的逗号分隔列表。 （注意我的 VB.NET 就是这么强大）。

MostRecentIDs as String() '' // Instance level variables
Const ListSize = 5

'' // in a method somewhere
context As HttpContext = HttpContext.Current
cookie As HttpCookie = context.Request.Cookies("mri")
mri As Queue(Of String)

If cookie Is Nothing Then
    mri = New Queue(Of String)(cookie.Value.Split(",".ToCharArray())
Else
    mri = New Queue(Of String)
    cookie = New HttpCookie("mri")
End If

If mri.Contains(Request.QueryString("id")) Then

    If mri.Count >= ListSize Then mri.Dequeue()

    mri.Enqueue(Request.QueryString("id"))

End If

MostRecentIDs = mri.ToArray();

cookie.Value = String.Join(",", MostRecentIDs)
cookie.Expires = DateTime.Now.AddDays(365)

context.Response.Add(cookie)

• 现在您可以通过简单的字符串数组访问最新的产品 ID。
• 此代码处理尚未创建 cookie 的情况。
• cookie 本身要小得多。
• 可以轻松地对列表大小的管理进行参数化。

上面的代码基于我放入一个空的 ASPX 文件的下面经过测试的 C# 代码：-

const int listSize = 8;
string[] _mru;

protected void Page_Load(object sender, EventArgs e)
{
    HttpCookie cookie = Request.Cookies["mru"];
    Queue<string> mru;
    if (cookie != null)
    {
        mru = new Queue<string>(cookie.Value.Split(','));
    }
    else
    {
        mru = new Queue<string>();
        cookie = new HttpCookie("mru"); 
    }

    if (!mru.Contains(Request.QueryString["id"]))
    {
        if (mru.Count >= listSize) mru.Dequeue();

        mru.Enqueue(Request.QueryString["id"]);
    }

    _mru = mru.ToArray();

    cookie.Value = String.Join(",", _mru);
    cookie.Expires = DateTime.Now.AddDays(365);

    Response.Cookies.Add(cookie);

}

Answer 2

如果我正确理解您的问题，我将这样做:)
如果产品数量少于 5 个，只需添加新产品。否则将 product0 替换为 product1 直到 4，然后在 4 处添加新产品

    If productcount < 5 Then 'Do the null value check before this
        HttpContext.Current.Response.Cookies("xxx")("productcount") = productCount + 1
        HttpContext.Current.Response.Cookies("xxx")("product" & productCount + 1) = ""

    Else
        For i = 0 To productcount - 1
           'Replace product 0 with 1, 1 with 2...till 3 with 4 
            HttpContext.Current.Response.Cookies("xxx")("product" & i & "") = HttpContext.Current.Response.Cookies("xxx")("product" & i + 1& "")

       Next
       HttpContext.Current.Response.Cookies("xxx")("product" & 4 & "") =  Request.QueryString("id")
    End If

Answer 3

Anthony 完美地回答了这个问题，但为了将来参考和使用 VB 的人，代码如下：

    Imports System.Collections.Generic

    Const listSize As Integer = 5
    Private _mru As String()

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim cookie As HttpCookie = Request.Cookies("mru")

        Dim mru As Queue(Of String)
        If cookie IsNot Nothing Then
            mru = New Queue(Of String)(cookie.Value.Split(","c))
        Else
            mru = New Queue(Of String)()
            cookie = New HttpCookie("mru")
        End If

        If mru.Count >= listSize Then
            mru.Dequeue()
        End If

        mru.Enqueue(Request.QueryString("id"))

        _mru = mru.ToArray()

        cookie.Value = [String].Join(",", _mru)
        cookie.Expires = DateTime.Now.AddDays(365)


        Response.Cookies.Add(cookie)
End Sub

也非常感谢这里的所有贡献者。