Flink-1.9流计算开发：五、keyBy、sum、print函数

public class StreamTest {
    private static final Logger LOG = LoggerFactory.getLogger(StreamTest.class);
    private static final String[] TYPE = { "苹果", "梨", "西瓜", "葡萄", "火龙果" };

    public static void main(String[] args) throws Exception {
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        //添加自定义数据源,每秒发出一笔订单信息{商品名称,商品数量}
        DataStreamSource<Tuple2<String, Integer>> orderSource = env.addSource(new SourceFunction<Tuple2<String, Integer>>() {
            private volatile boolean isRunning = true;
            private final Random random = new Random();
            @Override
            public void run(SourceContext<Tuple2<String, Integer>> ctx) throws Exception {
                while (isRunning) {
                    TimeUnit.SECONDS.sleep(1);
                    ctx.collect(Tuple2.of(TYPE[random.nextInt(TYPE.length)], 1));
                }
            }
            @Override
            public void cancel() {
                isRunning = false;
            }

        }, "order-info");

        orderSource
        //将订单流按Tuple的第一个字段分区--商品名称
        .keyBy(0)
        //累加订单流Tuple的第二个字段--商品数量
        .sum(1)
        //将流中的每个元素按标准输出打印
        .print();

        env.execute("Flink Streaming Java API Skeleton");
    }
}

3> (苹果,1)
3> (西瓜,1)
2> (火龙果,1)
2> (火龙果,2)
1> (葡萄,1)
3> (梨,1)
2> (火龙果,3)
3> (苹果,2)
3> (苹果,3)
3> (西瓜,2)
1> (葡萄,2)
2> (火龙果,4)
3> (苹果,4)
......

https://github.com/chaoxxx/learn-flink-stream-api/blob/master/src/main/java/fun/cosmozhu/session5/StreamTest.java