请给我举一个AggregateFunction和ProcessAkllWindowFunction一起使用的例子
时间: 2024-02-12 15:08:49 浏览: 17
好的,一个例子是计算在一个时间窗口内某个字段的平均值。具体实现可以使用ProcessAllWindowFunction来计算总和和计数,然后使用AggregateFunction计算平均值。以下是一个示例代码:
```
public static class AverageFunction implements AggregateFunction<Integer, Tuple2<Integer, Integer>, Double> {
@Override
public Tuple2<Integer, Integer> createAccumulator() {
return new Tuple2<>(0, 0);
}
@Override
public Tuple2<Integer, Integer> add(Integer value, Tuple2<Integer, Integer> accumulator) {
return new Tuple2<>(accumulator.f0 + value, accumulator.f1 + 1);
}
@Override
public Double getResult(Tuple2<Integer, Integer> accumulator) {
return (double) accumulator.f0 / accumulator.f1;
}
@Override
public Tuple2<Integer, Integer> merge(Tuple2<Integer, Integer> a, Tuple2<Integer, Integer> b) {
return new Tuple2<>(a.f0 + b.f0, a.f1 + b.f1);
}
}
public static class MyProcessAllWindowFunction extends ProcessAllWindowFunction<Integer, Double, TimeWindow> {
@Override
public void process(Context context, Iterable<Integer> elements, Collector<Double> out) throws Exception {
Tuple2<Integer, Integer> sumAndCount = new Tuple2<>(0, 0);
for (Integer element : elements) {
sumAndCount.f0 += element;
sumAndCount.f1++;
}
Double avg = new AverageFunction().getResult(sumAndCount);
out.collect(avg);
}
}
DataStream<Integer> stream = ...;
stream.windowAll(TumblingEventTimeWindows.of(Time.seconds(10)))
.aggregate(new AverageFunction(), new MyProcessAllWindowFunction());
```
在这个例子中,`AverageFunction`是一个计算平均值的`AggregateFunction`,而`MyProcessAllWindowFunction`是一个使用`AverageFunction`计算平均值的`ProcessAllWindowFunction`。在`MyProcessAllWindowFunction`中,我们首先计算窗口内所有元素的总和和计数,然后使用`AverageFunction`计算平均值,并将结果发射到下游。