DataStream Transformations

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

        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

//        filterFunction(env);

//        unionFunction(env);

//        splitSelectFunction(env);

        env.execute("JavaDataStreamTransformationApp");

    }

filter:

public static void filterFunction(StreamExecutionEnvironment env){

    DataStreamSource<Long> data = env.addSource(new JavaCustomNonParallelSourceFunction());

    data.map(new MapFunction<Long, Long>() {

        public Long map(Long value) throws Exception {

            System.out.println("value = [" + value + "]");

            return value;

        }

    }).filter(new FilterFunction<Long>() {

        public boolean filter(Long value) throws Exception {

            return value % 2 == 0;

        }

    }).print().setParallelism(1);

}

结果：

value = [1]

value = [2]

2

value = [3]

value = [4]

4

value = [5]

value = [6]

6

。。。

union:

public static void unionFunction(StreamExecutionEnvironment env) {

    DataStreamSource<Long> data1 = env.addSource(new JavaCustomNonParallelSourceFunction());

    DataStreamSource<Long> data2 = env.addSource(new JavaCustomNonParallelSourceFunction());

    data1.union(data2).union(data1).print().setParallelism(3);

}

3> 1

2> 1

2> 1

1> 2

3> 2

2> 2

1> 3

1> 3

3> 3

。。。

split select:

public static void splitSelectFunction(StreamExecutionEnvironment env) {

    DataStreamSource<Long> data = env.addSource(new JavaCustomNonParallelSourceFunction());

    SplitStream<Long> splits = data.split(new OutputSelector<Long>() {

        public Iterable<String> select(Long value) {

            List<String> output = new ArrayList<String>();

            if (value % 2 == 0) {

                output.add("even");

            }else {

                output.add("odd");

            }

            return output;

        }

    });

    splits.select("even").print().setParallelism(2);

}

1> 2

2> 4

1> 6

2> 8

1> 10

2> 12

1> 14

2> 16

1> 18

2> 20

。。。