Sink

一、flink处理的主要过程

从上一节wordcount的示例可以看到，flink的处理过程分为下面3个步骤：

1.1 、添加数据源addSource，这里的数据源可以是文件，网络数据流，MQ，Mysql...

1.2、数据转换(或者称为数据处理)，比如wordcount里的处理过程，就是把一行文本，按空格拆分成单词，并按单词计数

1.3、将处理好的结果，输出(或下沉)到目标系统，这里的目标系统，可以是控制台、MQ、Redis、Mysql、ElasticSearch...

可能有同学有疑问，上节wordcount里，最后的结果只是调用了1个print方法，好象并没有addSink的过程？

org.apache.flink.streaming.api.datastream.DataStream#print() 可以看下这个方法的源码：

	/**
	 * Writes a DataStream to the standard output stream (stdout).
	 *
	 * <p>For each element of the DataStream the result of {@link Object#toString()} is written.
	 *
	 * <p>NOTE: This will print to stdout on the machine where the code is executed, i.e. the Flink
	 * worker.
	 *
	 * @return The closed DataStream.
	 */
	@PublicEvolving
	public DataStreamSink<T> print() {
		PrintSinkFunction<T> printFunction = new PrintSinkFunction<>();
		return addSink(printFunction).name("Print to Std. Out");
	}

其实最后1行，就已经调用了addSink

二、kafka基本操作

下面将把之前WordCount的流式处理版本，其中的Source与Sink改成常用的Kafka：

注：不熟悉kafka的同学，可以参考下面的步骤学习kafka的常用命令行（kafka老手可跳过）

到kafka官网下载最新的版本，并解压到本机。

2.1 启动zookeeper

.\zookeeper-server-start.bat ..\..\config\zookeeper.properties

2.2 启动kafka

.\kafka-server-start.bat ..\..\config\server.properties

2.3 查看topic list

.\kafka-topics.bat --list --zookeeper localhost:2181

2.4 启动procduer

.\kafka-console-producer.bat --broker-list localhost:9092 --topic test1

2.5 启动consumer

.\kafka-console-consumer.bat --bootstrap-server localhost:9092 --topic test1

添加Source

1 <dependency>
2     <groupId>org.apache.flink</groupId>
3     <artifactId>flink-connector-kafka-0.11_2.12</artifactId>
4     <version>1.11.2</version>
5 </dependency>

View Code

代码：

Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("zookeeper.connect", "localhost:2181");
props.put("group.id", "test-read-group");
props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("auto.offset.reset", "latest");

DataStreamSource<String> text = env.addSource(new FlinkKafkaConsumer011<>(
        "test1",
        new SimpleStringSchema(),
        props));

添加Transform

DataStream<Tuple2<String, Integer>> counts = text.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
    @Override
    public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
        //将每行按word拆分
        String[] tokens = value.toLowerCase().split("\\b+");

        //收集(类似:map-reduce思路)
        for (String token : tokens) {
            if (token.trim().length() > 0) {
                out.collect(new Tuple2<>(token.trim(), 1));
            }
        }
    }
})
//按Tuple2里的第0项，即：word分组
.keyBy(value -> value.f0)
//然后对Tuple2里的第1项求合
.sum(1);

添加Sink

counts.addSink(new FlinkKafkaProducer010<>("localhost:9092", "test2",
        (SerializationSchema<Tuple2<String, Integer>>) element -> ("(" + element.f0 + "," + element.f1 + ")").getBytes()));

如上图，程序运行起来后，在kafka的proceduer终端，随便输入一些word，相当于发送消息给flink，然后idea的console控制台，输出的统计结果。

如果此时，再开一个kafka的consumer，可以看到统计结果，也同步发送到了test2这个topic，即实现了kafka的sink.

附：

完整pom文件

  1 <?xml version="1.0" encoding="UTF-8"?>
  2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  3          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  4     <modelVersion>4.0.0</modelVersion>
  5 
  6     <groupId>com.cnblogs.yjmyzz</groupId>
  7     <artifactId>flink-demo</artifactId>
  8     <version>0.0.1-SNAPSHOT</version>
  9 
 10     <properties>
 11         <java.version>1.8</java.version>
 12         <flink.version>1.11.2</flink.version>
 13     </properties>
 14 
 15     <dependencies>
 16         
 17         <!-- flink -->
 18         <dependency>
 19             <groupId>org.apache.flink</groupId>
 20             <artifactId>flink-core</artifactId>
 21             <version>${flink.version}</version>
 22         </dependency>
 23 
 24         <dependency>
 25             <groupId>org.apache.flink</groupId>
 26             <artifactId>flink-java</artifactId>
 27             <version>${flink.version}</version>
 28         </dependency>
 29 
 30         <dependency>
 31             <groupId>org.apache.flink</groupId>
 32             <artifactId>flink-scala_2.12</artifactId>
 33             <version>${flink.version}</version>
 34         </dependency>
 35 
 36         <dependency>
 37             <groupId>org.apache.flink</groupId>
 38             <artifactId>flink-clients_2.12</artifactId>
 39             <version>${flink.version}</version>
 40         </dependency>
 41 
 42         <!--kafka-->
 43         <dependency>
 44             <groupId>org.apache.flink</groupId>
 45             <artifactId>flink-connector-kafka-0.11_2.12</artifactId>
 46             <version>1.11.2</version>
 47         </dependency>
 48 
 49         <dependency>
 50             <groupId>org.apache.flink</groupId>
 51             <artifactId>flink-test-utils-junit</artifactId>
 52             <version>${flink.version}</version>
 53         </dependency>
 54     </dependencies>
 55 
 56     <repositories>
 57         <repository>
 58             <id>central</id>
 59             <layout>default</layout>
 60             <url>https://repo1.maven.org/maven2</url>
 61         </repository>
 62         <repository>
 63             <id>bintray-streamnative-maven</id>
 64             <name>bintray</name>
 65             <url>https://dl.bintray.com/streamnative/maven</url>
 66         </repository>
 67     </repositories>
 68 
 69     <build>
 70         <plugins>
 71             <plugin>
 72                 <artifactId>maven-compiler-plugin</artifactId>
 73                 <version>3.1</version>
 74                 <configuration>
 75                     <source>1.8</source>
 76                     <target>1.8</target>
 77                 </configuration>
 78             </plugin>
 79 
 80             <!-- Scala Compiler -->
 81             <plugin>
 82                 <groupId>net.alchim31.maven</groupId>
 83                 <artifactId>scala-maven-plugin</artifactId>
 84                 <version>4.4.0</version>
 85                 <executions>
 86                     <execution>
 87                         <id>scala-compile-first</id>
 88                         <phase>process-resources</phase>
 89                         <goals>
 90                             <goal>compile</goal>
 91                         </goals>
 92                     </execution>
 93                 </executions>
 94                 <configuration>
 95                     <jvmArgs>
 96                         <jvmArg>-Xms128m</jvmArg>
 97                         <jvmArg>-Xmx512m</jvmArg>
 98                     </jvmArgs>
 99                 </configuration>
100             </plugin>
101 
102         </plugins>
103     </build>
104 
105 </project>

View Code

完整java文件

package com.cnblogs.yjmyzz.flink.demo;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.serialization.SerializationSchema;
import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.api.java.tuple.Tuple2;
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.connectors.kafka.FlinkKafkaConsumer011;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer010;
import org.apache.flink.util.Collector;

import java.util.Properties;

/**
 * @author 菩提树下的杨过(http://yjmyzz.cnblogs.com/)
 */
public class KafkaStreamWordCount {

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

        // 1 设置环境
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // 2. 定义数据
        Properties props = new Properties();
        props.put("bootstrap.servers", "localhost:9092");
        props.put("zookeeper.connect", "localhost:2181");
        props.put("group.id", "test-read-group");
        props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("auto.offset.reset", "latest");

        DataStreamSource<String> text = env.addSource(new FlinkKafkaConsumer011<>(
                "test1",
                new SimpleStringSchema(),
                props));

        // 3. 处理逻辑
        DataStream<Tuple2<String, Integer>> counts = text.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
            @Override
            public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
                //将每行按word拆分
                String[] tokens = value.toLowerCase().split("\\b+");

                //收集(类似:map-reduce思路)
                for (String token : tokens) {
                    if (token.trim().length() > 0) {
                        out.collect(new Tuple2<>(token.trim(), 1));
                    }
                }
            }
        })
        //按Tuple2里的第0项，即：word分组
        .keyBy(value -> value.f0)
        //然后对Tuple2里的第1项求合
         .sum(1);

        // 4. 打印结果
        counts.addSink(new FlinkKafkaProducer010<>("localhost:9092", "test2",
                (SerializationSchema<Tuple2<String, Integer>>) element -> ("(" + element.f0 + "," + element.f1 + ")").getBytes()));
        counts.print();

        // execute program
        env.execute("Kafka Streaming WordCount");

    }
}

posted @ 2020-11-19 22:24 菩提树下的杨过阅读(671) 评论(0) 编辑收藏举报

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