flink自定义窗口分配器

背景

我们知道处理常用的滑动窗口分配器，滚动窗口分配器，全局窗口分配器，会话窗口分配器外，我们可以实现自己的自定义窗口分配器，以实现我们的自己的窗口逻辑

自定义窗口分配器的实现

package wikiedits.assigner;

import com.google.common.collect.Lists;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.windowing.assigners.GlobalWindows;
import org.apache.flink.streaming.api.windowing.assigners.WindowAssigner;
import org.apache.flink.streaming.api.windowing.triggers.EventTimeTrigger;
import org.apache.flink.streaming.api.windowing.triggers.Trigger;
import org.apache.flink.streaming.api.windowing.windows.GlobalWindow;
import org.apache.flink.streaming.api.windowing.windows.TimeWindow;

import java.util.Collection;
import java.util.Collections;

public class IntervalWindowAssigner
        extends WindowAssigner<Object, TimeWindow> {
    private static final long serialVersionUID = 1L;
    private long windowSize = 60 * 1000L;

    private IntervalWindowAssigner() {}

    @Override
    public Collection<TimeWindow> assignWindows(
            Object element, long timestamp, WindowAssignerContext context) {

        long startTime = timestamp -  (timestamp % windowSize);
        long endTime = startTime + windowSize;

        return Lists.newArrayList(new TimeWindow(startTime, endTime));
    }

    @Override
    public Trigger<Object, TimeWindow> getDefaultTrigger(StreamExecutionEnvironment env) {
        return EventTimeTrigger.create();
    }

    @Override public TypeSerializer<TimeWindow> getWindowSerializer(ExecutionConfig executionConfig) {
        return new TimeWindow.Serializer();
    }

    @Override public boolean isEventTime() {
        return true;
    }
}

注意，TimeWindow时间窗口是左边右开的形式，参见下图所示

代码里面是以maxTimeStamp()为准的