flink详解(flinkml)

max聚合：获取一组数据流中最大的值

示例环境

java.version: 1.8.x
flink.version: 1.11.1

示例数据源 （项目码云下载）

Flink 系例 之 搭建开发环境与数据

Max.java

import com.flink.examples.DataSource;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.typeinfo.Types;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.tuple.Tuple3;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import java.util.List;

public class Max {

    
    public static void main(String[] args) throws Exception {
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        List> tuple3List = DataSource.getTuple3ToList();
        DataStream> dataStream = env.fromCollection(tuple3List)
                .map(new MapFunction, Tuple2>() {
                    @Override
                    public Tuple2 map(Tuple3 tuple3) throws Exception {
                        return new Tuple2<>(tuple3.f1,tuple3.f2);
                    }
                })
                .returns(Types.TUPLE(Types.STRING,Types.INT))
                .keyBy((KeySelector, String>) k ->k.f0)
                //按数量窗口滚动，每3个输入数据流，计算一次
                .countWindow(3)
                .max(1);
        dataStream.print();
        env.execute("flink Max job");
    }
}

打印结果

2> (man,30)
4> (girl,32)