三、使用 nc -lk 监听socketTextStream

 linux命令

[root@localhost ~]# nc -lk 7777
-bash: nc: command not found

 yum install -y nc

[root@localhost ~]# nc -lk 7777      
hello world nihao are you

代码

package com.robert.flink.wcTest;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.typeinfo.Types;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

public class FlinStreamSocketWordCountPrintTest {

    public static void main(String[] args) throws Exception {

        //get runtime environment
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        //read content into dataset from file
        DataStream stringDataSet = env.socketTextStream("192.168.56.10",7777);


        //count word appeared times
        DataStream> sum = stringDataSet.flatMap((FlatMapFunction>) (value, collector) -> {

            String[] words = value.split(" ");
            for (String word : words) {
                collector.collect(new Tuple2<>(word, 1));
            }
        }).returns(Types.TUPLE(Types.STRING, Types.INT)).keyBy(0).sum(1);

        //print content of dataset
        sum.print();

        env.execute();

    }

}

流程：1.先运行以上linux命令 中的nc -lk 7777  如果没有nc则yum安装

          2.然后运行java代码开启flink的socket流监听

         然后输入数据

效果：输入单词 以空格分开 一次换行打印一次 分组统计出现次数如下