1.实验目的

（1）通过实验掌握基本的Flink编程方法。

（2）掌握用IntelliJ IDEA工具编写Flink程序的方法。

2.实验平台

（1）Ubuntu18.04（或Ubuntu16.04）。

（2）IntelliJ IDEA。

（3）Flink1.9.1。

3.实验步骤

（1）使用IntelliJ IDEA工具开发WordCount程序

在Linux系统中安装IntelliJ IDEA，然后使用IntelliJ IDEA工具开发WordCount程序，并打包成JAR文件，提交到Flink中运行。

WordCountData

import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;

public class WordCountData {
    public static final String[] WORDS=new String[]{"My name is LCZ, I am a college student studying at Shijiazhuang Railway University."};
    public WordCountData() {
    }
    public static DataSet<String> getDefaultTextLineDataset(ExecutionEnvironment env){
        return env.fromElements(WORDS);
    }
}


WordCountTokenizer

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;
public class WordCountTokenizer implements FlatMapFunction<String, Tuple2<String,Integer>>{
    public WordCountTokenizer(){}
    public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
        String[] tokens = value.toLowerCase().split("\\W+");
        int len = tokens.length;
        for(int i = 0; i<len;i++){
            String tmp = tokens[i];
            if(tmp.length()>0){
                out.collect(new Tuple2<String, Integer>(tmp,Integer.valueOf(1)));
            }
        }
    }
}

WordCount

import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.operators.AggregateOperator;
import org.apache.flink.api.java.utils.ParameterTool;
public class WordCount {
    public WordCount(){}
    public static void main(String[] args) throws Exception {
        ParameterTool params = ParameterTool.fromArgs(args);
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        env.getConfig().setGlobalJobParameters(params);
        Object text;

        if(params.has("input")){
            text = env.readTextFile(params.get("input"));
        }else{
            text = WordCountData.getDefaultTextLineDataset(env);
        }
        AggregateOperator counts = ((DataSet)text).flatMap(new WordCountTokenizer()).groupBy(new int[]{0}).sum(1);

        if(params.has("output")){
            counts.writeAsCsv(params.get("output"),"\n", " ");
            env.execute();
        }else{
            counts.print();
        }
    }
}

（2）数据流词频统计

使用Linux系统自带的NC程序模拟生成数据流，不断产生单词并发送出去。编写Flink程序对NC程序发来的单词进行实时处理，计算词频，并把词频统计结果输出。要求首先在IntelliJ IDEA中开发和调试程序，然后，再打成JAR包部署到Flink中运行。

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.util.Collector;
public class TongJi {
    public static void main(String[] args) throws Exception {
//定义socket的端口号
        int port;
        try {
            ParameterTool parameterTool = ParameterTool.fromArgs(args);
            port = parameterTool.getInt("port");
        } catch (Exception e) {
            System.err.println("指定port参数，默认值为9000");
            port = 9001;
        }
//获取运行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
//连接socket获取输入的数据
        DataStreamSource<String> text = env.socketTextStream("127.0.0.1", port, "\n");
//计算数据
        DataStream<WordWithCount> windowCount = text.flatMap(new FlatMapFunction<String, WordWithCount>() {
                    public void flatMap(String value, Collector<WordWithCount> out) throws Exception {
                        String[] splits = value.split("\\s");
                        for (String word : splits) {
                            out.collect(new WordWithCount(word, 1L));
                        }
                    }
                })//打平操作，把每行的单词转为<word,count>类型的数据
                .keyBy("word")//针对相同的word数据进行分组
                .timeWindow(Time.seconds(2), Time.seconds(1))//指定计算数据的窗口大小和滑动窗口大小
                .sum("count");
//把数据打印到控制台
        windowCount.print()
                .setParallelism(1);//使用一个并行度
//注意：因为flink是懒加载的，所以必须调用execute方法，上面的代码才会执行
        env.execute("streaming word count");
    }
    /**
     * 主要为了存储单词以及单词出现的次数
     */
    public static class WordWithCount {
        public String word;
        public long count;
        public WordWithCount() {
        }
        public WordWithCount(String word, long count) {
            this.word = word;
            this.count = count;
        }
        @Override
        public String toString() {
            return "WordWithCount{" +
                    "word='" + word + '\'' +
                    ", count=" + count +
                    '}';
        }
    }
}
Pom.xml
<?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>TongJi</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.apache.flink/flink-java -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-java</artifactId>
            <version>1.9.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.flink/flink-streaming-java -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_2.12</artifactId>
            <version>1.9.2</version>
<!--            <scope>provided</scope>-->
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.flink/flink-clients -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients_2.12</artifactId>
            <version>1.9.2</version>
        </dependency>
    </dependencies>

</project>