使用flink 写一个wordcount

可以使用以下代码实现基于 Flink 的 WordCount：

import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.util.Collector;

public class WordCount {
  public static void main(String[] args) throws Exception {
    final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

    DataSet<String> text = env.fromElements(
      "To be, or not to be, that is the question",
      "Whether 'tis nobler in the mind to suffer",
      "The slings and arrows of outrageous fortune",
      "Or to take arms against a sea of troubles");

    DataSet<Tuple2<String, Integer>> counts =
      text.flatMap(new LineSplitter())
          .groupBy(0)
          .sum(1);

    counts.print();
  }

  public static final class LineSplitter implements FlatMapFunction<String, Tuple2<String, Integer>> {
    @Override
    public void flatMap(String value, Collector<Tuple2<String, Integer>> out) {
      for (String word : value.split("\\s")) {
        out.collect(new Tuple2<String, Integer>(word, 1));
      }
    }
  }
}

这个程序会读取一个包含多行文本的数据集，对每个单词进行计数，并输出每个单词出现的次数。