flink窗口函数ReduceFunction、AggregateFunction、ProcessFunction实例
1、ReduceFunction增量,输入、状态、输出类型相同importorg.apache.flink.api.common.eventtime.SerializableTimestampAssigner;importorg.apache.flink.api.common.eventtime.WatermarkStrategy;importorg.apache.flink.api.common