| /* |
| * 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.examples.java.wordcount; |
| |
| import org.apache.flink.api.common.functions.FlatMapFunction; |
| import org.apache.flink.api.java.DataSet; |
| import org.apache.flink.api.java.ExecutionEnvironment; |
| import org.apache.flink.api.java.tuple.Tuple2; |
| import org.apache.flink.examples.java.wordcount.util.WordCountData; |
| import org.apache.flink.util.Collector; |
| |
| /** |
| * Implements the "WordCount" program that computes a simple word occurrence histogram |
| * 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 simple Flink program. |
| * <li>use Tuple data types. |
| * <li>write and use user-defined functions. |
| * </ul> |
| * |
| */ |
| @SuppressWarnings("serial") |
| public class WordCount { |
| |
| // ************************************************************************* |
| // PROGRAM |
| // ************************************************************************* |
| |
| public static void main(String[] args) throws Exception { |
| |
| if(!parseParameters(args)) { |
| return; |
| } |
| |
| // set up the execution environment |
| final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment(); |
| |
| // get input data |
| DataSet<String> text = getTextDataSet(env); |
| |
| DataSet<Tuple2<String, Integer>> counts = |
| // split up the lines in pairs (2-tuples) containing: (word,1) |
| text.flatMap(new Tokenizer()) |
| // group by the tuple field "0" and sum up tuple field "1" |
| .groupBy(0) |
| .sum(1); |
| |
| // emit result |
| if(fileOutput) { |
| counts.writeAsCsv(outputPath, "\n", " "); |
| // execute program |
| env.execute("WordCount Example"); |
| } else { |
| counts.print(); |
| } |
| |
| |
| } |
| |
| // ************************************************************************* |
| // USER FUNCTIONS |
| // ************************************************************************* |
| |
| /** |
| * Implements the string tokenizer that splits sentences into words as a user-defined |
| * FlatMapFunction. The function takes a line (String) and splits it into |
| * multiple pairs in the form of "(word,1)" ({@code Tuple2<String, Integer>}). |
| */ |
| public static final class Tokenizer implements FlatMapFunction<String, Tuple2<String, Integer>> { |
| |
| @Override |
| public void flatMap(String value, Collector<Tuple2<String, Integer>> out) { |
| // normalize and split the line |
| String[] tokens = value.toLowerCase().split("\\W+"); |
| |
| // emit the pairs |
| for (String token : tokens) { |
| if (token.length() > 0) { |
| out.collect(new Tuple2<String, Integer>(token, 1)); |
| } |
| } |
| } |
| } |
| |
| // ************************************************************************* |
| // 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 DataSet<String> getTextDataSet(ExecutionEnvironment env) { |
| if(fileOutput) { |
| // read the text file from given input path |
| return env.readTextFile(textPath); |
| } else { |
| // get default test text data |
| return WordCountData.getDefaultTextLineDataSet(env); |
| } |
| } |
| } |