共计 583 个字符，预计需要花费 2 分钟才能阅读完成。
| StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); | |
| env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime); | |
| dataStream.filter(data -> "test".equals(data.getTag())).keyBy("userId"); | |
| ...... |
执行报错：
| Exception in thread "main" org.apache.flink.api.common.InvalidProgramException: This type (GenericType<com.zixi.User>) cannot be used as key. | |
| at org.apache.flink.api.common.operators.Keys$ExpressionKeys.<init>(Keys.java:330) | |
| at org.apache.flink.streaming.api.datastream.DataStream.keyBy(DataStream.java:340) | |
| at com.zixi.main(UserTest.java:58) |
解决办法：
1. 提供默认无参构造函数
2. 字段名必须申明为 public
正文完
