//对某列而言，要细化到某个单元格可以判断rowIndex, columnIndex
{ header: "数量", dataIndex: "Number", sortable: true, width: 120,
        renderer: function(data, metadata, record, rowIndex, columnIndex, store) {
            if () {
                var tip =  "当前数量不足！";
                metadata.attr = 'ext:qtip="' + tip + '"';
                return '<span style="color:red;"><B>' + record.data["Number"] + '</B></span>';
            } else {
                return record.data["Number"];
            }
        }
},