flink基于事件时间的滑动窗口

// 创建一个滑动窗口DataStream
DataStream<Event> stream = ...

// 使用时间分配器指定事件时间戳
stream.assignTimestampsAndWatermarks(new MyTimestampExtractor());

// 定义滑动窗口的大小和间隔
Time windowSize = Time.minutes(5);
Time slideInterval = Time.minutes(2);

// 使用滑动窗口进行计算
DataStream<WindowedEvent> windowedStream = stream
    .window(SlidingEventTimeWindows.of(windowSize, slideInterval))
    .apply(new MyWindowFunction());

// 定义事件类
public class Event {
    public long timestamp;
    ...
}

// 定义带有窗口信息的事件类
public class WindowedEvent {
    public long windowStart;
    public long windowEnd;
    ...
}

// 定义时间分配器
public class MyTimestampExtractor implements AssignerWithPunctuatedWatermarks<Event> {
    public long extractTimestamp(Event element, long previousTimestamp) {
        return element.timestamp;
    }

    public Watermark checkAndGetNextWatermark(Event lastElement, long extractedTimestamp) {
        return new Watermark(extractedTimestamp - windowSize.toMilliseconds());
    }
}

// 定义窗口函数
public class MyWindowFunction extends WindowFunction<Event, WindowedEvent, Long, TimeWindow> {
    public void apply(Long key, TimeWindow window, Iterable<Event> input, Collector<WindowedEvent> out) {
        long windowStart = window.getStart();
        long windowEnd = window.getEnd();

        for (Event event : input) {
            WindowedEvent windowedEvent = new WindowedEvent();
            windowedEvent.windowStart = windowStart;
            windowedEvent.windowEnd = windowEnd;
            ...

            out.collect(windowedEvent);
        }
    }
}