轉換 transformation

map

一對一，輸入為一，輸出為一

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 MapTest {public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();DataStreamSource<String> dataStreamSource = env.readTextFile("xxx\hello.txt");SingleOutputStreamOperator<String> map = dataStreamSource.map(new MapFunction<String, String>() {@Overridepublic String map(String value) throws Exception {return value.split("\t")[0];}});map.print();env.execute("map test");} }

flatMap

一對多，一行進，多行出

import org.apache.flink.api.common.functions.FlatMapFunction; import org.apache.flink.streaming.api.datastream.DataStreamSource; import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator; import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment; import org.apache.flink.util.Collector;public class FlatMapTest {public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();DataStreamSource<String> dataStreamSource = env.readTextFile("xxx\hello.txt");SingleOutputStreamOperator<String> flatMap = dataStreamSource.flatMap(new FlatMapFunction<String, String>() {@Overridepublic void flatMap(String value, Collector<String> out) throws Exception {for (String word : value.split(" ")) {out.collect(word);}}});flatMap.print();env.execute("flatMap test");} }

filter

設置過濾條件

import org.apache.flink.streaming.api.datastream.DataStreamSource; import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator; import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment; import org.apache.flink.streaming.api.functions.sink.PrintSinkFunction;public class FilterTest {public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();DataStreamSource<String> dataStreamSource = env.readTextFile("xxx\hello.txt");SingleOutputStreamOperator<String[]> filter = dataStreamSource.map(text -> text.split(" ")).filter(text -> text[0].equals("001"));SingleOutputStreamOperator<String> map = filter.map(text -> text[1]);map.addSink(new PrintSinkFunction<>());env.execute("filter test");} }

keyBy

聚合，dataStream中用keyBy， dataSet中用groupBy

import org.apache.flink.api.common.functions.FlatMapFunction; import org.apache.flink.api.java.tuple.Tuple2; import org.apache.flink.streaming.api.datastream.DataStreamSource; import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator; import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment; import org.apache.flink.streaming.api.functions.sink.PrintSinkFunction; import org.apache.flink.util.Collector;public class KeyByTest {public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();env.setParallelism(1);DataStreamSource<String> dataStreamSource = env.readTextFile("xxx\hello.txt");SingleOutputStreamOperator<Tuple2<String, Integer>> sum = dataStreamSource.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {@Overridepublic void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {String[] strings = value.split(" ");for (String field : strings) {out.collect(new Tuple2<>(field, 1));}}}).keyBy(0).sum(1);sum.addSink(new PrintSinkFunction<>());env.execute("keyBy test");} }

reduce

import org.apache.flink.api.common.functions.FlatMapFunction; import org.apache.flink.api.common.functions.ReduceFunction; import org.apache.flink.api.java.tuple.Tuple2; import org.apache.flink.streaming.api.datastream.DataStreamSource; import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator; import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment; import org.apache.flink.util.Collector;public class ReduceTeset {public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();DataStreamSource<String> dataStreamSource = env.readTextFile("D:\\ifeng\\flinkTest\\src\\main\\java\\com\\ifeng\\zgx\\exercise\\data\\hello.txt");SingleOutputStreamOperator<Tuple2<String, Integer>> reduce = dataStreamSource.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {@Overridepublic void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {String[] strings = value.split(" ");for (String str : strings) {out.collect(new Tuple2<>(str, 1));}}}).keyBy(0).reduce(new ReduceFunction<Tuple2<String, Integer>>() {@Overridepublic Tuple2<String, Integer> reduce(Tuple2<String, Integer> value1, Tuple2<String, Integer> value2) throws Exception {return new Tuple2<>(value2.f0, value1.f1 + value2.f1);}});reduce.print();env.execute("reduce test");} }

hello.txt

ref

flink transformations
flink Basic API

總結

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