flink batch wordcount

1、POJO方式

public class WordCountPojo {
    public static class Word{
        private String word;
        private int frequency;

        public Word() {
        }

        public Word(String word, int frequency) {
            this.word = word;
            this.frequency = frequency;
        }

        public String getWord() {
            return word;
        }

        public void setWord(String word) {
            this.word = word;
        }

        public int getFrequency() {
            return frequency;
        }

        public void setFrequency(int frequency) {
            this.frequency = frequency;
        }

        @Override
        public String toString() {
            return "Word=" + word + " freq=" + frequency;
        }
    }

    /**
     * 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 Word objects.
     */
    public static final class Tokenizer implements FlatMapFunction<String, Word> {

        @Override
        public void flatMap(String value, Collector<Word> 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 Word(token, 1));
                }
            }
        }
    }

    public static void main(String args[]) throws Exception {
        final ParameterTool params = ParameterTool.fromArgs(args);

        // set up the execution environment
        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        // make parameters available in the web interface
        env.getConfig().setGlobalJobParameters(params);

        // get input data
        DataSet<String> text;
        if (params.has("input")) {
            // read the text file from given input path
            text = env.readTextFile(params.get("input"));
        } else {
            // get default test text data
            System.out.println("Executing WordCount example with default input data set.");
            System.out.println("Use --input to specify file input.");
            text = WordCountData.getDefaultTextLineDataSet(env);
        }

        DataSet<Word> counts = text
                // split up the lines into Word objects (with frequency = 1)
                .flatMap(new Tokenizer())
                // group by the field word and sum up the frequency
                .groupBy("word")
                .reduce(new ReduceFunction<Word>() {
                    @Override
                    public Word reduce(Word value1, Word value2) throws Exception {
                        return new Word(value1.word, value1.frequency + value2.frequency);
                    }
                });
        if (params.has("output")) {
            counts.writeAsText(params.get("output"), FileSystem.WriteMode.OVERWRITE);
            // execute program
            env.execute("WordCount-Pojo Example");
        } else {
            System.out.println("Printing result to stdout. Use --output to specify output path.");
            counts.print();
        }
    }

}

2、元组方式

public class WordCount {

    /**
     * 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) throws Exception {
            // 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<>(token, 1));
                }
            }
        }
    }

    public static void main(String args[]) throws Exception {
        final ParameterTool params = ParameterTool.fromArgs(args);

        // set up the execution environment
        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        // make parameters available in the web interface
        env.getConfig().setGlobalJobParameters(params);

        // get input data
        DataSet<String> text;
        if (params.has("input")) {
            // read the text file from given input path
            text = env.readTextFile(params.get("input"));
        } else {
            // get default test text data
            System.out.println("Executing WordCount example with default input data set.");
            System.out.println("Use --input to specify file input.");
            text = WordCountData.getDefaultTextLineDataSet(env);
        }

        DataSet<Tuple2<String,Integer>> counts = text
                // split up the lines in pairs (2-tuples) containing: (word,1)
                .flatMap(new Tokenizer())
                // group by the tuple field "0" and sum up tuple field "1"
                .groupBy(0)
                .reduce(new ReduceFunction<Tuple2<String, Integer>>() {
                    @Override
                    public Tuple2<String, Integer> reduce(Tuple2<String, Integer> value1, Tuple2<String, Integer> value2) throws Exception {
                        return new Tuple2<>(value1.f0,value1.f1+value2.f1);
                    }
                }); //等效于sum(1)
//                .sum(1);
        // emit result
        if(params.has("output")){
            counts.writeAsCsv(params.get("output"),"\n"," ");
            // execute program
            env.execute("WordCount batch");
        }else {
            System.out.println("Printing result to stdout. Use --output to specify output path.");
            counts.print();
        }

    }
}