HttpUtility.UrlEncode, HttpUtility.UrlPathEncode, HttpServerUtility.UrlEncode及HttpServerUtility.UrlPathEncode

在網路上看了官方資料和一些其它網友的比較說明，在這做個紀錄

以下是MSDN針對這四個function做的說明
HttpUtility.UrlEncode　HttpUtility.UrlPathEncode
Server.UrlEncode　Server.UrlPathEncode

大略說明一下它們之間的差異

1. HttpUtility.UrlEncode預設是使用UTF8編碼，而Server.UrlEncode是使用系統預設編碼；Server.UrlEncode會使用系統預設編碼做為參數代入並呼叫HttpUtility.UrlEncode做編碼動作，這點可由.NET Reflector來驗証
2. Server.UrlPathEncode會呼叫HttpUtility.UrlEncode做編碼動作，而HttpUtility.UrlEncode預設使用UTF8編碼，所以Server.UrlPathEncode會以UTF8編碼，這點可由.NET Reflector來驗証
3. HttpUtility.UrlEncode將空格編碼為+，而HttpUtility.UrlPathEncode將空格編碼為%20
4. HttpUtility.UrlEncode會針對完整的URL做編碼，包含Query String；Server.UrlPathEncode則不對Query String做編碼
5. HttpUtility.UrlEncode及HttpUtility.UrlPathEncode為靜態函式，而Server.UrlEncode及Server.UrlPathEncode需在ASP.NET中以Page.Server(或直接以Server)取得HttpServerUtility物件後才可以使用^[註1]
6. HttpUtility.UrlEncode會針對冒號(:)或斜線(/)做編碼，如http://會編碼成http%3a%2f%2f。所以HttpUtility.UrlEncode不宜對URL的路徑部份做編碼，以免執行如Response.Rediret功能時，無法導向正確網址，應改由HttpUtility.UrlPathEncode對URL路徑部份做編碼^[註2]

測試範例

UrlEncodeTest.aspx

 <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Redirect to UrlEncodeTest.aspx using HttpUtility.UrlEncode" />
 <p>
 <asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="Redirect to UrlEncodeTest.aspx using HttpUtility.UrlPathEncode" />
 </p>
 <p>
 <asp:Button ID="Button3" runat="server" OnClick="Button3_Click" Text="Redirect to UrlEncodeTest.aspx?param1=參數值1&amp;param2=value2 using HttpUtility.UrlEncode" />
 </p>
 <p>
 <asp:Button ID="Button4" runat="server" OnClick="Button4_Click" Text="Redirect to UrlEncodeTest.aspx?param1=參數值1&amp;param2=value2 using HttpUtility.UrlPathEncode" />
 </p>
 <p>
 <asp:Button ID="Button5" runat="server" OnClick="Button5_Click" Text="Redirect to UrlEncodeTest.aspx?param=我 是 空 白 using HttpUtility.UrlEncode" />
 </p>
 <p>
 <asp:Button ID="Button6" runat="server" OnClick="Button6_Click" Text="Redirect to UrlEncodeTest.aspx?param=我 是 空 白 using HttpUtility.UrlPathEncode" />
 </p>

UrlEncodeTest.aspx.cs

private string url = "http://localhost:10710/UrlEncodeTest.aspx";

protected void Page_Load(object sender, EventArgs e)
{
    if(!string.IsNullOrEmpty(Request.QueryString["param"]))
    {
        Response.Write(Request.QueryString["param"] + "<br>");
    }

    if(!string.IsNullOrEmpty(Request.QueryString["param1"]))
    {
        Response.Write(Request.QueryString["param1"] + "<br>");
    }

    if(!string.IsNullOrEmpty(Request.QueryString["param2"]))
    {
        Response.Write(Request.QueryString["param2"] + "<br>");
    }
}

protected void Button1_Click(object sender, EventArgs e)
{
    Response.Redirect(HttpUtility.UrlEncode(url));
}

protected void Button2_Click(object sender, EventArgs e)
{
    Response.Redirect(HttpUtility.UrlPathEncode(url));
}

protected void Button3_Click(object sender, EventArgs e)
{
    url += "?param1=參數值1&param2=value2";
    Response.Redirect(HttpUtility.UrlEncode(url));
}

protected void Button4_Click(object sender, EventArgs e)
{
    url += "?param1=參數值1&param2=value2";
    Response.Redirect(HttpUtility.UrlPathEncode(url));
}

protected void Button5_Click(object sender, EventArgs e)
{
    url += "?param=我 是 空 白";
    Response.Redirect(HttpUtility.UrlEncode(url));
}

protected void Button6_Click(object sender, EventArgs e)
{
    url += "?param=我 是 空 白";
    Response.Redirect(HttpUtility.UrlPathEncode(url));
}

備註

1. 當然，您也可以在類別庫專案中以HttpContext物件來取得HttpServerUtility，如System.Web.HttpContext.Current.Server
2. 小弟在研究MSDN時發現Server.UrlPathEncode的範例似乎有誤，測試發現Server.UrlPathEncode並不會對冒號(:)或斜線(/)做編碼，而範例顯示是會編碼的