Flink DataStream之Union合并流

• 新建类

package test01;

import jdk.nashorn.internal.runtime.regexp.joni.Config;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

public class TestUnion {

    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment executionEnvironment = StreamExecutionEnvironment.getExecutionEnvironment(new Configuration());
        executionEnvironment.setParallelism(1);

        //Union合并流的流数据类型必须一致，如果不一致，需要在合并前先转换类型，使其一致

        //创建要合并的流
        DataStreamSource stream1 = executionEnvironment.fromElements("a", "b", "c");
        DataStreamSource stream2 = executionEnvironment.fromElements("aa", "bb", "cc");
        DataStreamSource stream3 = executionEnvironment.fromElements("aaa", "bbb", "ccc");

        //方式一：多次调用union
        //DataStream union = stream1.union(stream2).union(stream3);

        //方式二：一次调用，中间用逗号隔开
        DataStream union = stream1.union(stream2, stream3);
        union.print();

        executionEnvironment.execute();


    }
}

• 运行程序

方式一：

 方式二：