docs: function(val, index, rule){
      //存在url，并且url不是http方式
      var isHttpUrl = val.indexOf('//') > -1;
      var ret = false;
      if (!isHttpUrl){
        var uri = imageUrlReg.exec(val);
        if (uri){
          var imgurl = url.parse(uri[1], true);
          var params = imgurl.query;
          var id = params['id'] || 0;
          ret = imgurl.pathname.replace(/\\+/g, '/');
          //过滤图片
          if (!(PARAMS['nosprite'] in params)){
            //设置第一个图片为sprite图片位置
            if (!this.get('imgPath')){
              this.set('imgPath', path.dirname(ret));
            }
  
            var preParam = this.get('preParam');
            var _id = this.get('id');
            if (_id == id){
              this.initSpriteConf(params);
              //依次初始化图片配置
              preParam.forEach(this.initSpriteConf, this);
              preParam = [];
            } else if (_id < id){
              //如果id提前出现，既id为0的图片没有出现之前，id是1的已经出现了，把
              //当前参数存在数组preParam中
              var isNewImg = preParam.every(function(params){
                return params.id < id;
              });
              if (isNewImg) preParam.push(params);
            }
            this.set('preParam', preParam);
          } else {
            var cssImgs = this.get('cssImgs');
            cssImgs.push(ret);
            rule.value[index] = val.replace(imgurl.pathname, ret);
            ret = false;
          }
        }
      }
  
      return ret;
    }