【Flink】Source入门

1 预定义Source

import org.apache.flink.api.common.RuntimeExecutionMode;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

import java.util.Arrays;

public class SourceExamples {
    
    
    public static void main(String[] args) throws Exception {
    
    
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setRuntimeMode(RuntimeExecutionMode.STREAMING);
        // 基于可变参数
        DataStream<String> ds1 = env.fromElements("hadoop,spark,flink", "hadoop spark hdfs", "flink");
        // 基于集合
        DataStream<String> ds2 = env.fromCollection(Arrays.asList("hadoop,spark,flink", "hadoop spark hdfs", "flink"));
        // 基于文件
        DataStream<String> ds3 = env.readTextFile("SourceExamples.java");
        // 基于文件-HDFS
        DataStream<String> ds4 = env.readTextFile("hdfs://localhost:9000/user/hadoop/flink/wordcount/output.txt");
        // 基于Socket
        DataStream<String> ds5 = env.socketTextStream("localhost", 9999);

        ds1.print();
        ds2.print();
        ds3.print();
        ds4.print();
        ds5.print();

        env.execute();
    }
}

2 自定义Source

2.1 自定义类为Source

Source 类继承 RichParallelSourceFunction 并重写 run 方法

import org.apache.flink.api.common.RuntimeExecutionMode;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.source.RichParallelSourceFunction;

import java.util.Random;

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

        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        env.setRuntimeMode(RuntimeExecutionMode.AUTOMATIC);

        DataStream<User> userDS = env.addSource(new UserSource());

        userDS.print();

        env.execute();
    }
}

class User {
    
    
    private int id;
    private int gender;

    public User(int id, int gender) {
    
    
        this.id = id;
        this.gender = gender;
    }

    @Override
    public String toString() {
    
    
        return "User{" +
                "id=" + id +
                ", gender=" + gender +
                '}';
    }
}

class UserSource extends RichParallelSourceFunction<User> {
    
    

    private Boolean flag = true;

    @Override
    public void run(SourceContext<User> out) throws Exception {
    
    
        Random random = new Random();
        while (flag){
    
    
            Thread.sleep(1000);
            int id = random.nextInt(100);
            int gender = random.nextInt(2);
            out.collect(new User(id,gender));
        }
    }

    @Override
    public void cancel() {
    
    
        flag = false;
    }
}