Flink 开发指南

package org.apache.flink.streaming.examples.socket;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.typeinfo.Types;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.windowing.assigners.TumblingProcessingTimeWindows;
import org.apache.flink.streaming.api.windowing.time.Time;

/**
 * Implements a streaming windowed version of the "WordCount" program.
 *
 * <p>This program connects to a server socket and reads strings from the socket. The easiest way to
 * try this out is to open a text server (at port 12345) using the <i>netcat</i> tool via
 *
 * <pre>
 * nc -l 12345 on Linux or nc -l -p 12345 on Windows
 * </pre>
 *
 * <p>and run this example with the hostname and the port as arguments.
 */
public class SocketWindowWordCount {

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

        // the host and the port to connect to
        final String hostname;
        final int port;
        try {
            final ParameterTool params = ParameterTool.fromArgs(args);
            hostname = params.has("hostname") ? params.get("hostname") : "localhost";
            port = params.getInt("port");
        } catch (Exception e) {
            System.err.println(
                    "No port specified. Please run 'SocketWindowWordCount "
                            + "--hostname <hostname> --port <port>', where hostname (localhost by default) "
                            + "and port is the address of the text server");
            System.err.println(
                    "To start a simple text server, run 'netcat -l <port>' and "
                            + "type the input text into the command line");
            return;
        }

        // get the execution environment
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // get input data by connecting to the socket
        DataStream<String> text = env.socketTextStream(hostname, port, "\n");

        // parse the data, group it, window it, and aggregate the counts
        DataStream<WordWithCount> windowCounts =
                text.flatMap(
                                (FlatMapFunction<String, WordWithCount>)
                                        (value, out) -> {
                                            for (String word : value.split("\\s")) {
                                                out.collect(new WordWithCount(word, 1L));
                                            }
                                        },
                                Types.POJO(WordWithCount.class))
                        .keyBy(value -> value.word)
                        .window(TumblingProcessingTimeWindows.of(Time.seconds(5)))
                        .reduce((a, b) -> new WordWithCount(a.word, a.count + b.count))
                        .returns(WordWithCount.class);

        // print the results with a single thread, rather than in parallel
        windowCounts.print().setParallelism(1);

        env.execute("Socket Window WordCount");
    }

    // ------------------------------------------------------------------------

    /** Data type for words with count. */
    public static class WordWithCount {

        public String word;
        public long count;

        @SuppressWarnings("unused")
        public WordWithCount() {}

        public WordWithCount(String word, long count) {
            this.word = word;
            this.count = count;
        }

        @Override
        public String toString() {
            return word + " : " + count;
        }
    }
}

Flink SQL 如下：

```sql
create table UserOrder(
  user_id int,
  money_amount int,
  ts AS localtimestamp,
  WATERMARK FOR ts AS ts
) with (
  'connector' = 'datagen',
  'rows-per-second' = '1',
  'fields.user_id.min' = '1',
  'fields.user_id.max' = '10',
  'fields.money_amount.min' = '1',
  'fields.money_amount.max' = '100'
);

create table UserMoneyAmount (
  user_id int,
  total_amount int,
  primary key (user_id) not enforced
) with ('connector' = 'print');

insert into
  UserMoneyAmount
select
  user_id,
  sum(money_amount) as total_amount
from
  UserOrder
group by
  user_id;