Word Count Batch

package com.atguigu.wc;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.operators.AggregateOperator;
import org.apache.flink.api.java.operators.DataSource;
import org.apache.flink.api.java.operators.FlatMapOperator;
import org.apache.flink.api.java.operators.UnsortedGrouping;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;

/**
 * TODO DataSet API 实现 wordcount（不推荐）
 */
public class WordCountBatchDemo {
    public static void main(String[] args) throws Exception {
        // TODO 1. 创建执行环境
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        // TODO 2.读取数据：从文件中读取
        DataSource<String> lineDS = env.readTextFile("input/word.txt");

        // TODO 3.切分、转换 （word，1）
        FlatMapOperator<String, Tuple2<String, Integer>> wordAndOne = lineDS.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
            @Override
            public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
                // TODO 3.1 按照 空格 切分单词
                String[] words = value.split(" ");
                // TODO 3.2 将 单词 转换为 （word，1）
                for (String word : words) {
                    Tuple2<String, Integer> wordTuple2 = Tuple2.of(word, 1);
                    //TODO 3.3 使用 Collector 向下游发送数据
                    out.collect(wordTuple2);
                }
            }
        });

        // TODO 4.按照 word 分组
        UnsortedGrouping<Tuple2<String, Integer>> wordAndOneGroupBy = wordAndOne.groupBy(0);
        // TODO 5.各分组内聚合
        AggregateOperator<Tuple2<String, Integer>> sum = wordAndOneGroupBy.sum(1); // 1是位置，表示第二个元素

        // TODO 6.输出
        sum.print();
    }
}