Maven配置pom文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>com.atguigu</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <flink.version>1.17.0</flink.version>
    </properties>


    <dependencies>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients</artifactId>
            <version>${flink.version}</version>
        </dependency>
    </dependencies>

</project>

java编写wordcount代码

基于DataSet API(过时的,不推荐)
之后用 DataStream API

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;

public class WordCountBatchDemo {
    public static void main(String[] args) throws Exception {
        //1.创建执行环境
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        //2.读取数据，从文件中读取
        DataSource<String> lineDS = env.readTextFile("input/word.txt");
        //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 {
                //Todo3.1 按照空格 切分单词
                String[] words = value.split(" ");
                //Todo3.2 将单词转换为(word,1)
                for (String word : words) {
                    Tuple2<String, Integer> wordTuple2 = Tuple2.of(word, 1);
                    //Todo3.3 调用采集器collector 向下游发送数据
                    out.collect(wordTuple2);

                }
            }
        });
        //4.按照word分组
        UnsortedGrouping<Tuple2<String, Integer>> wordAndOneGroupBy = wordAndOne.groupBy(0);
        //5.各分组内聚合
        AggregateOperator<Tuple2<String, Integer>> sum = wordAndOneGroupBy.sum(1);
        //6.输出
        sum.print();
    }
}