基础上手

项目创建

创建一个 maven 项目，引入以下两个依赖

1、基础上手

1.1 项目创建

创建一个 maven 项目，引入以下两个依赖

  <dependencies>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-streaming-java</artifactId>
        <version>1.18.0</version>
    </dependency>

    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-clients</artifactId>
        <version>1.18.0</version>
    </dependency>

</dependencies>

1.2 样例

编写一段流式处理的代码，利用 nc 工具来模拟数据流。可以发现我们输入数据，该数据就被 flink 接收到并产生结果

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

        //todo 1、创建执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        //todo 2、获取数据源
        DataStreamSource<String> inputData = env.socketTextStream("8.140.207.120",8081);
        //todo 3、处理数据
        SingleOutputStreamOperator<Tuple2<String, Integer>> result = inputData.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
            @Override
            public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
                String[] words = value.split(" ");
                for (String word : words) {
                    Tuple2<String, Integer> tuple2 = Tuple2.of(word, 1);
                    out.collect(tuple2);
                }
            }
        });

        //分组
        KeyedStream<Tuple2<String, Integer>, String> kbStream = result.keyBy(new KeySelector<Tuple2<String, Integer>, String>() {
            @Override
            public String getKey(Tuple2<String, Integer> value) throws Exception {
                //返回第一个元素
                return value.f0;
            }
        });
        //聚合
        SingleOutputStreamOperator<Tuple2<String,Integer>> data = kbStream.sum(1);
        //todo 4、输出数据
        data.print();
        //todo 5、执行
        env.execute();
    }