3-flink api概述

1、抽象分層

3.1-api抽象分層.png
  1. ProcessFunction:提供對時(shí)間、事件、狀態(tài)的細(xì)粒度控制,用于處理一些復(fù)雜事件的邏輯上,易用性較低
  2. DataStreamApi&DataSet:核心api,提供對流/批數(shù)據(jù)的操作處理,基于函數(shù)式的,簡單易用
  3. SQL&TableApi:flink sql的集成基于apache calcite,使用比其他api更靈活方便

2、datastream api

datastream api主要包含以下3塊內(nèi)容

1、datasource

數(shù)據(jù)的輸入來源,來源方式主要有以下幾種

  1. 來自文件:讀取文本文件,將符合TextInputFormat規(guī)范的文件,將字符串返回

    StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
    DataStream<String> text = env.readTextFile("file:///filePath");
    
  2. 來自集合:fromCollection(Collection),fromElements(T ...)等

  3. 來自socket

    StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
    DataStreamSource<String> text = env.socketTextStream(hostname, port, delimiter);
    
  4. 自定義輸入

    自定義輸入源有兩種方式:

    • 實(shí)現(xiàn)SourceFunction接口來自定義無并行度的數(shù)據(jù)源

      demo:每一秒產(chǎn)生一條數(shù)據(jù)的source

      package streaming.source;
      
      import org.apache.flink.streaming.api.functions.source.SourceFunction;
      
      
      /**
       * @author xiaolong
       */
      public class InputSource implements SourceFunction<Long> {
      
          private boolean isRunning = true;
      
          private Long counter = 1L;
      
      
          @Override
          public void cancel() {
              isRunning = false;
          }
      
      
          @Override
          public void run(SourceContext<Long> context) throws Exception {
              while (isRunning) {
                  context.collect(counter);
                  counter++;
                  Thread.sleep(1000);
              }
      
          }
      }
      
  • 實(shí)現(xiàn)ParallelSourceFunction接口或者繼承RichParallelSourceFunction來自定義具有并行度的數(shù)據(jù)源

2、transform

flink提供了很多算子,經(jīng)常使用的有以下這些:

  • Map:輸入一個(gè)元素,可以進(jìn)行邏輯運(yùn)算,輸出一個(gè)元素

  • FlatMap:輸入一個(gè)元素,輸出多個(gè)或零個(gè)元素

  • Filter:元素過濾,符合條件的會保留

  • Union:合并多個(gè)流,必須保證合并的流必須是格式一致的

    修改InputSource的類型為String,再新增一個(gè)InputStringSource

    package streaming.source;
    
    import org.apache.flink.streaming.api.functions.source.SourceFunction;
    
    import java.util.Arrays;
    import java.util.List;
    import java.util.Random;
    
    
    /**
     * @author xiaolong
     */
    public class InputStringSource implements SourceFunction<String> {
    
        private boolean isRunning = true;
    
        private List<String> alphabet = Arrays.asList("a", "b", "c", "d", "e", "f", "g");
    
    
        @Override
        public void cancel() {
            isRunning = false;
        }
    
    
        @Override
        public void run(SourceContext<String> ctx) throws Exception {
            while (isRunning) {
                Random random = new Random();
                ctx.collect(alphabet.get(random.nextInt(alphabet.size())));
                Thread.sleep(1000);
            }
        }
    }
    

    測試代碼:

    import org.apache.flink.streaming.api.datastream.DataStreamSource;
    import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
    
    import streaming.source.InputSource;
    import streaming.source.InputStringSource;
    
    
    /**
     * @author xiaolong
     */
    public class TestSource {
    
        public static void main(String[] args) throws Exception {
            StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
            DataStreamSource<String> source = env.addSource(new InputSource());
            DataStreamSource<String> source2 = env.addSource(new InputStringSource());
            source.union(source2).print();
            env.execute("testInputSource");
        }
    }
    

    輸出結(jié)果如下:

3.2-合并流輸出結(jié)果.png
  • Connect:只能合并兩個(gè)流,可以不必保證流的格式一致性

  • coMap/coFlatMap:在ConnectedStream中使用這種函數(shù),類似于Map和FlatMap

    import org.apache.flink.streaming.api.datastream.DataStream;
    import org.apache.flink.streaming.api.datastream.DataStreamSource;
    import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
    import org.apache.flink.streaming.api.functions.co.CoFlatMapFunction;
    import org.apache.flink.util.Collector;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import streaming.source.InputSource;
    import streaming.source.InputStringSource;
    
    /**
     * @author xiaolong
     */
    public class TestSource {
    
        public static void main(String[] args) throws Exception {
            StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
            DataStreamSource<Long> intSource = env.addSource(new InputSource());
            DataStreamSource<String> strSource = env.addSource(new InputStringSource());
            DataStream<List<String>> result = intSource.connect(strSource).flatMap(new CoFlatMapFunction<Long, String, List<String>>() {
                List<String> list = new ArrayList<>();
    
                @Override
                public void flatMap1(Long aLong, Collector<List<String>> collector) throws Exception {
                    list.add(aLong.toString());
                    collector.collect(list);
                }
    
                @Override
                public void flatMap2(String s, Collector<List<String>> collector) throws Exception {
                    list.add(s);
                    collector.collect(list);
                }
            });
            result.print();
            env.execute("testInputSource");
        }
    }
    
    

測試結(jié)果:


3.4-合并不同流輸出結(jié)果.png
  • Split:根據(jù)規(guī)則把一個(gè)流切分為多個(gè)流

  • Select:選擇切分后的流,與Split配合使用

  • KeyBy:根據(jù)指定的Key進(jìn)行分組,Key相同的數(shù)據(jù)會進(jìn)入到同一個(gè)分區(qū)

  • Aggregation:聚合算子,例如sum,max等

  • Reduce:將上一條數(shù)據(jù)與當(dāng)前數(shù)據(jù)進(jìn)行聚合操作,返回一條新數(shù)據(jù)

    import org.apache.flink.api.common.functions.ReduceFunction;
    import org.apache.flink.api.java.tuple.Tuple2;
    import org.apache.flink.streaming.api.datastream.DataStreamSource;
    import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
    import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
    
    
    /**
     * @author xiaolong
     */
    public class TestSource {
    
        public static void main(String[] args) throws Exception {
            StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
            DataStreamSource<Tuple2<Integer, Integer>> source = env.fromElements(Tuple2.of(1, 10), Tuple2.of(2, 20), Tuple2.of(2, 21), Tuple2.of(1, 11), Tuple2.of(2, 22));
            SingleOutputStreamOperator<Tuple2<Integer, Integer>> reduce = source.keyBy(0).reduce(new ReduceFunction<Tuple2<Integer, Integer>>() {
                @Override
                public Tuple2<Integer, Integer> reduce(Tuple2<Integer, Integer> t2, Tuple2<Integer, Integer> t1) throws Exception {
                    return new Tuple2<>(t1.f0, t2.f1 + t1.f1);
                }
            });
            reduce.print();
            env.execute("testInputSource");
        }
    }
    

    測試結(jié)果:

3.3-reduce輸出.png
  • 分區(qū):

    1. 隨機(jī)分區(qū):dataStream.shuffle();

    2. 重新平衡:dataStream.rebalance(),對數(shù)據(jù)進(jìn)行再平衡、重分區(qū)和消除數(shù)據(jù)傾斜

    3. 重新調(diào)節(jié):dataStream.rescale

      2和3的區(qū)別是rebalance會產(chǎn)生全量重分區(qū),rescale重新調(diào)節(jié)的過程是,如果上游有4個(gè)并發(fā)操作,下游有2個(gè)并發(fā),重新調(diào)節(jié)后上游的2個(gè)并發(fā)會分配給下游的1個(gè)并發(fā)操作,反之亦然。

    4. 自定義分區(qū):自定義分區(qū)需要實(shí)現(xiàn)partitionCustom方法

      import org.apache.flink.api.common.functions.MapFunction;
      import org.apache.flink.api.common.functions.Partitioner;
      import org.apache.flink.api.java.tuple.Tuple1;
      import org.apache.flink.streaming.api.datastream.DataStreamSource;
      import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
      
      import java.util.Arrays;
      import java.util.List;
      
      import streaming.source.InputStringSource;
      
      
      /**
       * @author xiaolong
       */
      public class TestSource {
      
          public static void main(String[] args) throws Exception {
              StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
              DataStreamSource<String> strSource = env.addSource(new InputStringSource());
              List<String> list = Arrays.asList("a", "b", "c", "d");
              strSource.map(new MapFunction<String, Tuple1<String>>() {
                  @Override
                  public Tuple1<String> map(String s) throws Exception {
                      return new Tuple1<>(s);
                  }
              }).partitionCustom(new Partitioner<String>() {
                  @Override
                  public int partition(String s, int i) {
                      System.out.println("分區(qū)個(gè)數(shù):" + i);
                      if (list.contains(s)) {
                          return 0;
                      }else {
                          return 1;
                      }
                  }
              }, 0).print();
              env.execute("testFlinkJob");
          }
      }
      

      測試結(jié)果:


      3.5-自定義分區(qū).png

3、sink

flink有如下幾種sink操作:

  1. 標(biāo)準(zhǔn)輸出:print()/printToErr()

  2. 輸出到文檔或socket:writeAsCsv,writeAsText,writeToSocket

  3. 寫入到flink第三方存儲:ElasticSearch,Redis,kafkaProducer等

    測試從socket讀取數(shù)據(jù),寫入到kafka

    import org.apache.flink.streaming.api.datastream.DataStreamSource;
    import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
    import org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer011;
    import org.apache.flink.streaming.connectors.kafka.internals.KeyedSerializationSchemaWrapper;
    import org.apache.flink.streaming.util.serialization.SimpleStringSchema;
    
    import java.util.Properties;
    
    
    /**
     * @author xiaolong
     */
    public class TestSource {
    
        public static void main(String[] args) throws Exception {
            StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
            DataStreamSource<String> strSource = env.socketTextStream("localhost", 9000, "\n");
            Properties properties = new Properties();
            properties.put("bootstrap.servers", "xxxxxx"); // brokers地址
            properties.put("transaction.timeout.ms", 15 * 60 * 1000); // 設(shè)置FlinkKafkaProducer011的超時(shí)時(shí)間,默認(rèn)是1h, kafka服務(wù)默認(rèn)事務(wù)超時(shí)時(shí)間是15min,如果不設(shè)置會報(bào)錯(cuò)
            FlinkKafkaProducer011<String> myProducer = new FlinkKafkaProducer011<String>(
                    "kafkaDruid",  // kafka topic
                    new KeyedSerializationSchemaWrapper<String>(new SimpleStringSchema()),  // 序列化
                    properties,      // properties
                    FlinkKafkaProducer011.Semantic.EXACTLY_ONCE);  // kafka語義
    
            // 0.10+ 版本的 Kafka 允許在將記錄寫入 Kafka 時(shí)附加記錄的事件時(shí)間戳;
            // 此方法不適用于早期版本的 Kafka
            myProducer.setWriteTimestampToKafka(true);
            strSource.addSink(myProducer);
            strSource.print();
            env.execute("testFlinkJob");
    
        }
    }
    

    socket輸入:

3.7-socket輸入.png

測試結(jié)果,到kafka平臺上可查看到最新的消息:

3.6-數(shù)據(jù)寫入到kafka.png
  1. 自定義輸出,實(shí)現(xiàn)SinkFunction或RichSInkFunction接口
最后編輯于
?著作權(quán)歸作者所有,轉(zhuǎn)載或內(nèi)容合作請聯(lián)系作者
【社區(qū)內(nèi)容提示】社區(qū)部分內(nèi)容疑似由AI輔助生成,瀏覽時(shí)請結(jié)合常識與多方信息審慎甄別。
平臺聲明:文章內(nèi)容(如有圖片或視頻亦包括在內(nèi))由作者上傳并發(fā)布,文章內(nèi)容僅代表作者本人觀點(diǎn),簡書系信息發(fā)布平臺,僅提供信息存儲服務(wù)。

友情鏈接更多精彩內(nèi)容