flink从入门到精通系列之：map、flatmap、filter

import org.apache.flink.api.common.functions.FilterFunction;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.Collector;

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

         DataStream inputStream = env.readTextFile("/Users/fei.yang4/k8s/flink.txt");

         //map，把String转换长度输出
        SingleOutputStreamOperator mapStream = inputStream.map(new MapFunction() {

            @Override
            public Integer map(String value) throws Exception {
                return value.length();
            }
        });
        
        //flatmap，按逗号分割字段

        SingleOutputStreamOperator flatMapStream =
                inputStream.flatMap(new FlatMapFunction() {
            @Override
            public void flatMap(String value, Collector out) throws Exception {
                String[] fields = value.split(",");
                for (String field : fields)
                    out.collect(field);
            }
        });

        //filter，筛选
        SingleOutputStreamOperator filterStream = inputStream.filter(new FilterFunction() {
            @Override
            public boolean filter(String value) throws Exception {
                return value.equals("java");
            }
        });


        mapStream.print("map");
        flatMapStream.print("flatMap");
        filterStream.print("filter");

        env.execute();



    }
}