Flink学习(一)

一、Linux上部署Flink

1.先在服务器上安装jdk1.8

2.下载Flink

wget https://archive.apache.org/dist/flink/flink-1.12.1/flink-1.12.1-bin-scala_2.11.tgz

3.解压Flink并进入到目录

tar -xvf flink-1.12.1-bin-scala_2.11.tgz
cd /usr/local/src/flink-1.12.1

4.启动Flink

./bin/start-cluster.bat

通过 http://localhost:8081 访问 Flink 的 web 页面，该站点用于查看运行环境和资源、提交和监控 Flink 作业。

二、在idea上创建Flink的工程

1.在 IDEA 中创建 Flink 应用的模板工程

在如上的页面点击 “Add Archetype…”，然后再弹出的对话框填写如下内容

2.创建测试类

3.将官网的WordCount例子的代码拷贝到自己的项目中

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.streaming.api.datastream.DataStream;
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 FirstCase {
    public static void main(String[] args) throws Exception {

        // the port to connect to
        final int port = 8090;

        // get the execution environment
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // get input data by connecting to the socket
        DataStream<String> text = env.socketTextStream("192.168.109.138", port, "\n");

        // parse the data, group it, window it, and aggregate the counts
        DataStream<WordWithCount> windowCounts = text
                .flatMap(new FlatMapFunction<String, WordWithCount>() {
                    @Override
                    public void flatMap(String value, Collector<WordWithCount> out) {
                        for (String word : value.split("\\s")) {
                            out.collect(new WordWithCount(word, 1L));
                        }
                    }
                })
                .keyBy("word")
                .timeWindow(Time.seconds(5), Time.seconds(1))
                .reduce(new ReduceFunction<WordWithCount>() {
                    @Override
                    public WordWithCount reduce(WordWithCount a, WordWithCount b) {
                        return new WordWithCount(a.word, a.count + b.count);
                    }
                });

        // print the results with a single thread, rather than in parallel
        windowCounts.print().setParallelism(1);

        env.execute("Socket Window WordCount");
    }

    // Data type for words with count
    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 word + " : " + count;
        }
    }
}

4.启动 netcat 用于发数据

安装nc命令

yum install -y nc

启动 netcat 用于发数据

启动idea上的java程序用于接收netcat文本发送的

为什么控制台输出5次a,因为代码中的这句.timeWindow(Time.seconds(5), Time.seconds(1))
定义了一个滑动窗口，窗口大小为5秒，每1秒滑动一次

三、遇到的问题

问题：java项目启动的时候报错

解决方案：点击编辑配置

"Include dependencies with “Provided” scope"选择该项