ASP.net WebAPI 上传图片实例

[httppost]
public task<hashtable> imgupload()
{
    // 检查是否是 multipart/form-data
    if (!request.content.ismimemultipartcontent("form-data"))
        throw new httpresponseexception(httpstatuscode.unsupportedmediatype);
    //文件保存目录路径
    string savetemppath = "~/sayplaces/" + "/saypic/saypictemp/";
    string dirtemppath = httpcontext.current.server.mappath(savetemppath);
    // 设置上传目录
    var provider = new multipartformdatastreamprovider(dirtemppath);
    //var queryp = request.getquerynamevaluepairs();//获得查询字符串的键值集合
    var task = request.content.readasmultipartasync(provider).
        continuewith<hashtable>(o =>
        {
            hashtable hash = new hashtable();
            hash["error"] = 1;
            hash["errmsg"] = "上传出错";
            var file = provider.filedata[0];//provider.formdata
            string orfilename = file.headers.contentdisposition.filename.trimstart('"').trimend('"');
            fileinfo fileinfo = new fileinfo(file.localfilename);                    
            //最大文件大小
            int maxsize = 10000000;
            if (fileinfo.length <= 0)
            {
                hash["error"] = 1;
                hash["errmsg"] = "请选择上传文件。";
            }
            else if (fileinfo.length > maxsize)
            {
                hash["error"] = 1;
                hash["errmsg"] = "上传文件大小超过限制。";
            }
            else
            {
                string fileext = orfilename.substring(orfilename.lastindexof('.'));
                //定义允许上传的文件扩展名
                string filetypes = "gif,jpg,jpeg,png,bmp";
                if (string.isnullorempty(fileext) || array.indexof(filetypes.split(','), fileext.substring(1).tolower()) == -1)
                {
                    hash["error"] = 1;
                    hash["errmsg"] = "上传文件扩展名是不允许的扩展名。";
                }
                else
                {
                    string ymd = datetime.now.tostring("yyyymmdd", system.globalization.datetimeformatinfo.invariantinfo);
                    string newfilename = datetime.now.tostring("yyyymmddhhmmss_ffff", system.globalization.datetimeformatinfo.invariantinfo);
                    fileinfo.copyto(path.combine(dirtemppath, newfilename + fileext), true);
                    fileinfo.delete();
                    hash["error"] = 0;
                    hash["errmsg"] = "上传成功";
                }
            }
            return hash;
        });
    return task;
}