Flink1.8实现wordcount

之前已经记录了在Mac上安装Flink1.8

https://blog.csdn.net/zhangvalue/article/details/93166895

1️⃣、开始创建一个项目名为flink_begin的maven项目

2️⃣、pom.xml文件添加如下dependency：

        
            org.apache.flink
            flink-java
            1.8.0
        
        
        
            org.apache.flink
            flink-streaming-java_2.12
            1.8.0
            provided
        

        
        
            org.apache.flink
            flink-clients_2.12
            1.8.0
        
    

wordcount.java 文件如下：

/**
 * @ Author zhangsf
 * @CreateTime 2019-06-20 - 18:58
 */

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 WordCount {
    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 = 9000;
        }

        //获取运行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        //连接socket获取输入的数据
        DataStreamSource text = env.socketTextStream("127.0.0.1", port, "\n");

        //计算数据
        DataStream windowCount = text.flatMap(new FlatMapFunction() {
            public void flatMap(String value, Collector 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 +
                    '}';
        }
    }


}

此时需要将本机的终端上开一个端口号为9000的监听

nc -l 9000

准备就绪就可以开始run 起来了

可能会出现问题 

java.lang.NoClassDefFoundError: org/apache/flink/streaming/api/datastream/DataStream

 https://blog.csdn.net/zhangvalue/article/details/93165357 解决

启动起来之后在

输入hello hello world world world world flink flink flink flink flink，回车。在IDEA的控制台会显示如下单词和词频的信息