ASP.NET MVC2 项目经验错杂谈

我们在做项目的时候经常会遇到传附件的问题，一是如果附件不符合格式要求，我们要清空input file。二是点击附件超链接的时候如果附件不在，应该提示附件不存在。下来我们就看看怎么实现。先看一个控制器

/// <summary>
       /// 检查文件是否存在
       /// </summary>
       /// <param name="id"></param>
       /// <returns></returns>
       public JsonResult CheckFileExist(string id)
       {
           Appurtenances appurtenances = messageEntities.appurtenances.FirstOrDefault(app => app.serial == id);
           string fileName = appurtenances.file_name;
           string filePath = Server.MapPath(appurtenances.file_path);
           if (!System.IO.File.Exists(filePath))
           {
               strJson = "{suc:0,msg:'文件不存在'}";
           }
           else
           {
               strJson = "{suc:1,msg:'文件存在'}";
           }
           return Json(strJson, JsonRequestBehavior.AllowGet);
       }

/// <summary>
       /// 附件下载
       /// </summary>
       /// <param name="id"></param>
       /// <returns></returns>
       public ActionResult GetFile(string id)
       {
           Appurtenances appurtenances = messageEntities.appurtenances.FirstOrDefault(app => app.serial == id);
           string fileName = appurtenances.file_name;
           string filePath = Server.MapPath(appurtenances.file_path);
           FileStream f = new FileStream(filePath, FileMode.Open);
           byte[] bytes = new byte[(int)f.Length];
           f.Read(bytes, 0, bytes.Length);
           f.Close();
           Response.ContentType = "application/octet-stream";
           Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName + appurtenances.file_path.Substring(appurtenances.file_path.LastIndexOf(".")), System.Text.Encoding.UTF8));
           Response.BinaryWrite(bytes);
           Response.Flush();
           Response.End();
           return null;
       }

再看看js

function checkFileExist(myId) {

    $.ajax({
        url: "/Message/CheckFileExist/" + myId,
        datatype: "json", // 返回的数据类型
        type: "post",
        //async:false,
        success: function (data) {
            var json = eval("(" + data + ")");
            new BaseUtil(json).parsJSONError;
            if (json.suc == 0) {
                jAlert(json.msg, "提示信息");
            } else {
                $("#downLoadSendMsg" + myId).attr("href", "/Message/GetFile/" + myId);
                $("#downLoadSendMsg" + myId).removeAttr("onclick");
                if (window.ActiveXObject) {//IE
                    document.getElementById("downLoadSendMsg" + myId).click();
                }
            }
        }
    });
}

function readedMesAddUpdateAppendix(readedMesNum, rowid, readedMesUrl, readAppdName) {
    var readedMesNum = readedMesNum + 1;
    var mesupdNewRow = "<tr><td width='430px' height='15px' align='left'>附件" + readedMesNum + ":&nbsp;&nbsp;";
    mesupdNewRow += "<a href='javascript:void(0);' id='downLoadSendMsg" + rowid + "' onclick=checkFileExist('" + rowid + "')>" + readAppdName + "<\/a><\/td><\/tr>";
    jQuery("#readedMesShowAppdTabl").append(mesupdNewRow);
}

function deleteFile(file) {
    var ie = (navigator.appVersion.indexOf("MSIE") != -1); //IE
    var ff = (navigator.userAgent.indexOf("Firefox") != -1); //Firefox

    if (ie)
        refreshUploader($("input[name=" + file + "]")[0]);
    else
        $("input[name=" + file + "]").attr("value", "");
}

function refreshUploader(file) {
    var file2 = file.cloneNode(false);
    file2.onchange = file.onchange;
    file.parentNode.replaceChild(file2, file);
}

调用的时候仅需要传一个input file的name值即可。

最后来个实惠的，把sql转化为linq

select sourseware_id,COUNT(*) as num from cours_ewares as a  group by a.sourseware_id having COUNT(*) >1

List<IGrouping<string,EPA_Cours_Ewares>> courseEwaresList = (from ce in examinationPlanArrangementsEntities.cours_ewares
                                            group ce by ce.sourseware_id into c where c.Count()>1
                                            select c).ToList();

 关于分页，在写分页的时候先得到IQueryable<T>类型，然后再获得其count(),算出总页数和总记录数后，将IQueryable<T>转化为List<T>,因为IQueryable不会向数据库发送sql命令。