angular项目中由于某些原因设置了以下代码：

    // $locationProvider.html5Mode(true);

    $httpProvider.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded;charset=utf-8';

    /**
     * The workhorse; converts an object to x-www-form-urlencoded serialization.
     * @param {Object} obj
     * @return {String}
     */
    var param = function (obj) {
      var query = '', name, value, fullSubName, subName, subValue, innerObj, i;

      for (name in obj) {
        value = obj[name];

        if (value instanceof Array) {
          for (i = 0; i < value.length; ++i) {
            subValue = value[i];
            fullSubName = name + '[' + i + ']';
            innerObj = {};
            innerObj[fullSubName] = subValue;
            query += param(innerObj) + '&';
          }
        }
        else if (value instanceof Object) {
          for (subName in value) {
            subValue = value[subName];
            fullSubName = name + '[' + subName + ']';
            innerObj = {};
            innerObj[fullSubName] = subValue;
            query += param(innerObj) + '&';
          }
        }
        else if (value !== undefined && value !== null)
          query += encodeURIComponent(name) + '=' + encodeURIComponent(value) + '&';
      }

      return query.length ? query.substr(0, query.length - 1) : query;
    };

    // Override $http service's default transformRequest
    $httpProvider.defaults.transformRequest = [function (data) {
      return angular.isObject(data) && String(data) !== '[object File]' ? param(data) : data;
    }];

结果导致现在文件不能上传，最简单的一个form表单提交都不行：

  

    
    提交
  

向各位大神求助，怎么样能正常上传图片？急，很急啊，项目都已经延期一天了……谢谢！