Content-Disposition 響應頭，設置文件在瀏覽器打開還是下載

Content-Disposition屬性有兩種類型：inline 和 attachment

inline ：將文件內容直接顯示在頁面

attachment：彈出對話框讓用戶下載

code:

　　context.Response.ContentType = "text/plain";
        string fileName = context.Request["fileName"];
        if(fileName!=null)
        {
            context.Response.AddHeader("Content-Disposition", "attachment;filename="+fileName);
            context.Response.WriteFile("downLoad/" + fileName);
        }