Flink入门（一）

本地执行Flink demo

• 开发工具IDEA
• maven配置

 <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <flink.version>1.4.2</flink.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-java</artifactId>
            <version>${flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_2.11</artifactId>
            <version>${flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients_2.11</artifactId>
            <version>${flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-wikiedits_2.11</artifactId>
            <version>${flink.version}</version>
        </dependency>
    </dependencies>

---

demo与官网的quick-start一样，只是启动用local模式，我这里写的是参考官网java代码,启动参数为 –port 9999

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 SocketWindowWordCount {

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

        final int port;
        try{
            final ParameterTool params=ParameterTool.fromArgs(args);
            port=params.getInt("port");
        }catch (Exception e){
            System.err.println("No port specified.Pleas run 'SocketWindowCount --port <port>'");
            return ;
        }

//        final StreamExecutionEnvironment env=StreamExecutionEnvironment.getExecutionEnvironment();

        //local模式
        final StreamExecutionEnvironment env=StreamExecutionEnvironment.createLocalEnvironment();

        DataStream<String> text=env.socketTextStream("localhost",port,"\n");

        DataStream<WordWithCount> windowCounts=text.flatMap(new FlatMapFunction<String, WordWithCount>() {
            @Override
            public void flatMap(String value, Collector<WordWithCount> out) throws Exception {
                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) throws Exception {
                return new WordWithCount(a.word,a.count+b.count);
            }
        });

        windowCounts.print().setParallelism(1);
        env.execute("Socket Window WordCount");
    }

    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;
        }
    }
}

模拟server发送消息。

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

//模拟服务端发送消息

public class ServerDemo {

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

        //本机localhost
        System.out.println(InetAddress.getLocalHost());
        ServerSocket server=new ServerSocket(9999);
        Socket client=server.accept();
        BufferedReader in =new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out=new PrintWriter(client.getOutputStream());
        while(true){
            String str=in.readLine();
            System.out.println(str);
            out.println(str);
            out.flush();
            if(str.equals("end"))
                break;
        }

        client.close();
    }
}