在ProcessWindowFunction上实现onTimer功能

import org.apache.flink.api.common.state.ValueState;
import org.apache.flink.api.common.state.ValueStateDescriptor;
import org.apache.flink.streaming.api.functions.windowing.ProcessWindowFunction;
import org.apache.flink.streaming.api.windowing.windows.TimeWindow;
import org.apache.flink.util.Collector;

public class MyProcessWindowFunction extends ProcessWindowFunction<InputType, OutputType, KeyType, TimeWindow> {

    private ValueState<Boolean> timerRegistered;

    @Override
    public void process(KeyType key, Context context, Iterable<InputType> elements, Collector<OutputType> out) throws Exception {
        // 在窗口中的每个元素到达时被调用

        // 注册定时器
        if (timerRegistered.value() == null) {
            long timerTime = context.window().getEnd(); // 获取窗口的结束时间
            context.timerService().registerEventTimeTimer(timerTime);
            timerRegistered.update(true);
        }

        // 处理窗口中的元素
        // ...

    }

    @Override
    public void onTimer(long timestamp, OnTimerContext ctx, Collector<OutputType> out) throws Exception {
        // 定时器触发时调用

        // 实现特定的操作
        // ...

    }

    @Override
    public void open(Configuration parameters) throws Exception {
        // 初始化状态
        ValueStateDescriptor<Boolean> timerRegisteredDescriptor = new ValueStateDescriptor<>("timerRegistered", Boolean.class);
        timerRegistered = getRuntimeContext().getState(timerRegisteredDescriptor);
    }
}