Map

package com.atguigu.transfrom;

import com.atguigu.bean.WaterSensor;
import com.atguigu.functions.MapFunctionImpl;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

public class MapDemo {
    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(1);

        DataStreamSource<WaterSensor> sensorDS = env.fromElements(
                new WaterSensor("s1", 1L, 1),
                new WaterSensor("s2", 2L, 2),
                new WaterSensor("s3", 3L, 3)
        );

        // TODO map算子： 一进一出

        // TODO 方式一： 匿名实现类
//        SingleOutputStreamOperator<String> map = sensorDS.map(new MapFunction<WaterSensor, String>() {
//            @Override
//            public String map(WaterSensor value) throws Exception {
//                return value.getId();
//            }
//        });

        // TODO 方式二： lambda表达式
//        SingleOutputStreamOperator<String> map = sensorDS.map(sensor -> sensor.getId());

        // TODO 方式三： 定义一个类来实现MapFunction
//        SingleOutputStreamOperator<String> map = sensorDS.map(new MyMapFunction());
        SingleOutputStreamOperator<String> map = sensorDS.map(new MapFunctionImpl());
        map.print();

        env.execute();
    }

    public static class MyMapFunction implements MapFunction<WaterSensor,String>{
        @Override
        public String map(WaterSensor value) throws Exception {
            return value.getId();
        }
    }
}