Flink kafka简单示例(一)统计topic中的单词后写入新的topic

最近在调研各种计算框架,在看完Kafka Stream之后也顺便看了一下最流行的Flink,结合我们业务场景试验了一些小demo。下面给出一个简单示例,基本和官方类似。只是使用了最新的版本Flink kafka connector以及最新版本的Flink 1.7.2(截止2019年2月)

示例简要介绍

第一步将kafka topic作为source添加到DataStream
第二步读取topic的内容进行单词统计(统计单词基本上是大数据框架的helloWorld程序)
第三步将统计结果进行转换
第四步将结果存入到kafka另外一个topic中。

关于Flink的connector以及现在=的kafkaconnector,参考https://ci.apache.org/projects/flink/flink-docs-release-1.7/dev/connectors/ 和https://ci.apache.org/projects/flink/flink-docs-release-1.7/dev/connectors/kafka.html

版本
本文试验中使用Flink 1.7.2版本,kafka_2.12-1.0.0。 因此引入了flink-connector-kafka_2.12的1.7.2版本。

由于从kafka读取的内容是string类型,向kafka写入的结果是string,因此DeserializationSchema直接使用自带的SimpleStringSchema。 关于如何使用deserializationSchema以及TypeInformationSerializationSchema 、JsonDeserializationSchema AvroDeserializationSchema 后面有机会再讨论(最近工作非常忙)。

主要代码

pom文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.yq</groupId>
    <artifactId>FlinkDemo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <flink.version>1.7.2</flink.version>
        <scala.binary.version>2.12</scala.binary.version>
    </properties>

    <dependencies>

        <!-- Flink dependencies -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-core</artifactId>
            <version>${flink.version}</version>
        </dependency>


        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-test-utils-junit</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <!-- core dependencies -->

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-scala_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-twitter_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-kafka_2.12</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-shaded-jackson</artifactId>
            <version>2.7.9-6.0</version>
        </dependency>

        <!-- test dependencies -->

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-test-utils_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
            <scope>test</scope>
            <type>test-jar</type>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-statebackend-rocksdb_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.21</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.21</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.20</version>
        </dependency>

        <!-- fastjson-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version> 1.2.31</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <!-- maven-resources-plugin插件 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.3</version>
                <configuration>
                    <!--源码的Java版本-->
                    <source>1.8</source>
                    <!--运行环境的Java版本-->
                    <target>1.8</target>
                    <encoding>UTF8</encoding>
                </configuration>
            </plugin>
 

            <!--simplify the name of example JARs for build-target/examples -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-antrun-plugin</artifactId>
                <version>1.7</version>
                <executions>
                    <execution>
                        <id>rename</id>
                        <phase>package</phase>
                        <goals>
                            <goal>run</goal>
                        </goals>
                        <configuration>
                            <target>
                                <copy file="${project.basedir}/target/FlinkDemo-${version}-KafkaConnector.jar" tofile="${project.basedir}/target/KafkaConnector.jar" />
                                <copy file="${project.basedir}/target/FlinkDemo-${version}-WordCount.jar" tofile="${project.basedir}/target/WordCount.jar" />
                            </target>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>

        <pluginManagement>
            <plugins>
                <!--This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself.-->
                <plugin>
                    <groupId>org.eclipse.m2e</groupId>
                    <artifactId>lifecycle-mapping</artifactId>
                    <version>1.0.0</version>
                    <configuration>
                        <lifecycleMappingMetadata>
                            <pluginExecutions>
                                <pluginExecution>
                                    <pluginExecutionFilter>
                                        <groupId>org.apache.maven.plugins</groupId>
                                        <artifactId>maven-dependency-plugin</artifactId>
                                        <versionRange>[2.9,)</versionRange>
                                        <goals>
                                            <goal>unpack</goal>
                                        </goals>
                                    </pluginExecutionFilter>
                                    <action>
                                        <ignore/>
                                    </action>
                                </pluginExecution>
                            </pluginExecutions>
                        </lifecycleMappingMetadata>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>

    </build>
</project>

主要代码

package com.yq.kafka;


import org.apache.flink.api.common.JobExecutionResult;
import org.apache.flink.api.common.JobID;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.api.java.tuple.Tuple2;
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.connectors.kafka.FlinkKafkaConsumer;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer;
import org.apache.flink.util.Collector;
import org.apache.kafka.clients.consumer.ConsumerConfig;

import java.util.Properties;

/**
 *  className: KafkaConnector
 *
 *  iot-temp topic输入内容类似, hello Java, Hello Test, Hello Python, 先统计为DataStream<Tuple2<String, Integer>>
 *  然后将DataStream<Tuple2<String, Integer>>转换为DataStream<String> , 最后将结果写入到kafka中,结果为Kafka and Flink says: (hello,3)格式
 * @author EricYang
 * @version 2019/3/11 14:50
 */
public class KafkaConnector {
    private static final String KAFKA_BROKERS = "localhost:9092";
    public static void main(String[] args) throws Exception {
        final ParameterTool parameterTool = ParameterTool.fromArgs(args);
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        env.getConfig().setGlobalJobParameters(parameterTool);

        Properties properties = new Properties();
        properties.put("group.id", "flink-kafka-connector");
        properties.put("bootstrap.servers", KAFKA_BROKERS);
        properties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");
        properties.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        properties.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");


        DataStream<String> messageStream = env.addSource(
                new FlinkKafkaConsumer<String>("iot-temp", new SimpleStringSchema(), properties));


        DataStream<Tuple2<String, Integer>> counts =
                // split up the lines in pairs (2-tuples) containing: (word,1)
                messageStream.flatMap(new Tokenizer())
                        // group by the tuple field "0" and sum up tuple field "1"
                        .keyBy(0).sum(1);

        DataStream<String> countsString =
                counts.map(new MapFunction<Tuple2<String, Integer>, String>() {
                    private static final long serialVersionUID = -6867736771747690202L;

                    @Override
                    public String map(Tuple2<String, Integer> value) throws Exception {
                        System.out.println("kafka msg=" + value);
                        return "Kafka and Flink says: " + value;
                    }
                });

        FlinkKafkaProducer<String> myProducer = new FlinkKafkaProducer<String>(
                KAFKA_BROKERS,
                "topic1",
                new SimpleStringSchema());

        myProducer.setWriteTimestampToKafka(true);
        countsString.addSink(myProducer);

      
        if (parameterTool.has("output")) {
            counts.writeAsText(parameterTool.get("output"));
        } else {
            System.out.println("Printing result to stdout. Use --output to specify output path.");
            counts.print();
        }

        // execute program
        JobExecutionResult result = env.execute("Streaming Kafka");
        JobID jobId = result.getJobID();
        System.out.println("jobId=" + jobId);
    }

    public static final class Tokenizer implements FlatMapFunction<String, Tuple2<String, Integer>> {

        @Override
        public void flatMap(String value, Collector<Tuple2<String, Integer>> out) {
            // normalize and split the line
            String[] tokens = value.toLowerCase().split("\\W+");

            // emit the pairs
            for (String token : tokens) {
                if (token.length() > 0) {
                    out.collect(new Tuple2<>(token, 1));
                }
            }
        }
    }

}

效果截图

在这里插入图片描述

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