| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.flink.streaming.examples.java8.wordcount; |
| |
| import org.apache.flink.api.java.tuple.Tuple2; |
| import org.apache.flink.examples.java.wordcount.util.WordCountData; |
| import org.apache.flink.streaming.api.datastream.DataStream; |
| import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment; |
| import org.apache.flink.util.Collector; |
| |
| import java.util.Arrays; |
| |
| /** |
| * Implements the streaming "WordCount" program that computes a simple word occurrences |
| * over text files. |
| * |
| * <p>The input is a plain text file with lines separated by newline characters. |
| * |
| * <p>Usage: <code>WordCount <text path> <result path></code><br> |
| * If no parameters are provided, the program is run with default data from {@link WordCountData}. |
| * |
| * <p>This example shows how to: |
| * <ul> |
| * <li>write a compact Flink Streaming program with Java 8 Lambda Expressions. |
| * </ul> |
| * |
| */ |
| public class WordCount { |
| |
| // ************************************************************************* |
| // PROGRAM |
| // ************************************************************************* |
| |
| public static void main(String[] args) throws Exception { |
| |
| if (!parseParameters(args)) { |
| return; |
| } |
| |
| // set up the execution environment |
| final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); |
| |
| // get input data |
| DataStream<String> text = getTextDataStream(env); |
| |
| DataStream<Tuple2<String, Integer>> counts = |
| // normalize and split each line |
| text.map(line -> line.toLowerCase().split("\\W+")) |
| // convert split line in pairs (2-tuples) containing: (word,1) |
| .flatMap((String[] tokens, Collector<Tuple2<String, Integer>> out) -> { |
| // emit the pairs with non-zero-length words |
| Arrays.stream(tokens) |
| .filter(t -> t.length() > 0) |
| .forEach(t -> out.collect(new Tuple2<>(t, 1))); |
| }) |
| // group by the tuple field "0" and sum up tuple field "1" |
| .keyBy(0) |
| .sum(1); |
| |
| // emit result |
| if (fileOutput) { |
| counts.writeAsCsv(outputPath); |
| } else { |
| counts.print(); |
| } |
| |
| // execute program |
| env.execute("Streaming WordCount Example"); |
| } |
| |
| // ************************************************************************* |
| // UTIL METHODS |
| // ************************************************************************* |
| |
| private static boolean fileOutput = false; |
| private static String textPath; |
| private static String outputPath; |
| |
| private static boolean parseParameters(String[] args) { |
| |
| if (args.length > 0) { |
| // parse input arguments |
| fileOutput = true; |
| if (args.length == 2) { |
| textPath = args[0]; |
| outputPath = args[1]; |
| } else { |
| System.err.println("Usage: WordCount <text path> <result path>"); |
| return false; |
| } |
| } else { |
| System.out.println("Executing WordCount example with built-in default data."); |
| System.out.println(" Provide parameters to read input data from a file."); |
| System.out.println(" Usage: WordCount <text path> <result path>"); |
| } |
| return true; |
| } |
| |
| private static DataStream<String> getTextDataStream(StreamExecutionEnvironment env) { |
| if (fileOutput) { |
| // read the text file from given input path |
| return env.readTextFile(textPath); |
| } else { |
| // get default test text data |
| return env.fromElements(WordCountData.WORDS); |
| } |
| } |
| } |