c# - 如何读取 cookie

Question

我正在尝试保存一个 cookie 然后读取它。无法编译，因为行代码中存在错误 (readcookie[....] )-

Response.Write("USERNAME: " + readCookie["userInfo"]["userName"].ToString());

它说 - “string.this[int] 的最佳重载方法匹配具有无效参数。

如果我写，

 Response.Write("USERNAME: " + readCookie["userInfo"][0].ToString());

然后我就可以编译了。它在 save_click 上显示“数据已保存”消息，但在 read_click 上显示错误 - 对象引用无效。首先是否正确保存了 cookie。我怎样才能从中读取。这是我的代码:

protected void btnSaveCookie_Click(object sender, EventArgs e)
    {
        HttpCookie myCookie = new HttpCookie("userInfo");
        myCookie.Values["userName"] = "Patrick";
        myCookie.Values["lastVisit"] = DateTime.Now.ToString();
        Response.Cookies.Add(myCookie);
        Response.Write("Data Stored Into Cookie....");
    }

protected void btnReadCookie_Click(object sender, EventArgs e)
    {
        HttpCookie readCookie = Request.Cookies.Get("userInfo");
        Response.Write("USERNAME: " + readCookie["userInfo"]["userName"].ToString());
        Response.Write("LAST VISIT: " + readCookie["userInfo"]["lastVisit"].ToString());
    }

Answer 1

这是读取和写入 cookie 的辅助方法。

/// <summary>
/// Sets cookie.
/// </summary>
/// <param name="cookieName">Cookie name</param>
/// <param name="cookieValue">Cookie value</param>
/// <param name="days">Days to be expired</param>
public static void SetCookie(string cookieName, string cookieValue, int days)
{
    try
    {
        var dt = DateTime.Now;

        var cookie = new HttpCookie(cookieName);
        cookie.Value = cookieValue;
        cookie.Expires = dt.AddDays(days);

        HttpContext.Current.Response.Cookies.Add(cookie);
    }
    catch (Exception ex)
    {
        // Log error
    }
}

/// <summary>
/// Gets cookie string
/// </summary>
/// <param name="cookieName">Cookie name</param>
/// <returns>Cookie string</returns>
public static String GetCookie(String cookieName)
{
    try
    {
        if (HttpContext.Current.Request.Cookies[cookieName] == null)
            return String.Empty;

        return HttpContext.Current.Request.Cookies[cookieName].Value;
    }
    catch (Exception ex)
    {
        // Log error
        return String.Empty;
    }
}

用法

protected void btnSaveCookie_Click(object sender, EventArgs e)
{
    SetCookie("userName", "Patrick", 1); // Save for one day
    SetCookie("lastVisit", DateTime.Now.ToString(), 1);
}

protected void btnReadCookie_Click(object sender, EventArgs e)
{
    Response.Write("USERNAME: " + GetCookie("userName"));
    Response.Write("LAST VISIT: " + GetCookie("lastVisit"));
}

---

原始问题的答案

如果您使用多值 Cookie(子键)，您希望检索值作为 readCookie["xxx"]。

protected void btnSaveCookie_Click(object sender, EventArgs e)
{
    HttpCookie myCookie = new HttpCookie("userInfo");
    myCookie.Values["userName"] = "Patrick";
    myCookie.Values["lastVisit"] = DateTime.Now.ToString();
    Response.Cookies.Add(myCookie);
    Response.Write("Data Stored Into Cookie....");
}

protected void btnReadCookie_Click(object sender, EventArgs e)
{
    HttpCookie readCookie = Request.Cookies.Get("userInfo");

    Response.Write("USERNAME: " + readCookie["userName"]);
    Response.Write("LAST VISIT: " + readCookie["lastVisit"]);
}