package ${package};
/*
* 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.
*/
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.Collector;
/**
* This example shows an implementation of WordCount with data from a text
* socket. To run the example make sure that the service providing the text data
* is already up and running.
*
* <p>
* To start an example socket text stream on your local machine run netcat from
* a command line: <code>nc -lk 9999</code>, where the parameter specifies the
* port number.
*
*
* <p>
* Usage:
* <code>SocketTextStreamWordCount <hostname> <port></code>
* <br>
*
* <p>
* This example shows how to:
* <ul>
* <li>use StreamExecutionEnvironment.socketTextStream
* <li>write a simple Flink program
* <li>write and use user-defined functions
* </ul>
*
* @see <a href="www.openbsd.org/cgi-bin/man.cgi?query=nc">netcat</a>
*/
public class SocketTextStreamWordCount {
//
// Program
//
public static void main(String[] args) throws Exception {
if (args.length != 2){
System.err.println("USAGE:\nSocketTextStreamWordCount <hostname> <port>");
return;
}
String hostName = args[0];
Integer port = Integer.parseInt(args[1]);
// set up the execution environment
final StreamExecutionEnvironment env = StreamExecutionEnvironment
.getExecutionEnvironment();
// get input data
DataStream<String> text = env.socketTextStream(hostName, port);
DataStream<Tuple2<String, Integer>> counts =
// split up the lines in pairs (2-tuples) containing: (word,1)
text.flatMap(new LineSplitter())
// group by the tuple field "0" and sum up tuple field "1"
.keyBy(0)
.sum(1);
counts.print();
// execute program
env.execute("Java WordCount from SocketTextStream Example");
}
//
// 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)" (Tuple2<String, Integer>).
*/
public static final class LineSplitter 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));
}
}
}
}
}