Flink:如何在滑动窗口中只处理窗口函数中的特定键

import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.windowing.assigners.SlidingProcessingTimeWindows;
import org.apache.flink.streaming.api.windowing.time.Time;

public class FlinkSlidingWindowExample {
    public static void main(String[] args) throws Exception {
        // 创建执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // 创建数据流
        DataStream<Tuple2<String, Integer>> dataStream = env.fromElements(
                new Tuple2<>("key1", 1),
                new Tuple2<>("key2", 2),
                new Tuple2<>("key1", 3),
                new Tuple2<>("key2", 4),
                new Tuple2<>("key1", 5)
        );

        // 按键分组
        DataStream<Tuple2<String, Integer>> keyedStream = dataStream.keyBy(0);

        // 定义滑动窗口
        DataStream<Tuple2<String, Integer>> windowedStream = keyedStream
                .window(SlidingProcessingTimeWindows.of(Time.seconds(10), Time.seconds(5)))
                .sum(1);

        // 过滤特定键的数据
        DataStream<Tuple2<String, Integer>> filteredStream = windowedStream
                .filter(tuple -> tuple.f0.equals("key1"));

        // 打印结果
        filteredStream.print();

        // 执行任务
        env.execute("Flink Sliding Window Example");
    }
}