the type miss expected process

在scala代码中报错如题目

.keyBy("itemType").process(new ProcessWindowFunction[DataInfo,GetItemTag,String,GlobalWindow] {
      override def process(key: String, context: Context, elements: Iterable[DataInfo], out: Collector[GetItemTag]): Unit = ???
    })

• 解决办法如下
  1、.keyBy 返回的是Tuple key类型
  2、检查引入的包是否正确

.keyBy("itemType").process[GetItemTag](new ProcessWindowFunction[DataInfo,GetItemTag,Tuple,GlobalWindow] {
      override def process(key: Tuple, context: Context, elements: Iterable[DataInfo], out: Collector[GetItemTag]): Unit = {
        
      }
    }

• fastjson在scala中使用，不要使用scala的class对象，全部对象必须使用java，否则报错

    val s = JSON.toJSONString(params,SerializerFeature.WriteMapNullValue)