Content-Disposition 响应头，设置文件在浏览器打开还是下载

Content-Disposition属性有两种类型：inline 和 attachment

inline ：将文件内容直接显示在页面

attachment：弹出对话框让用户下载

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);
        }