02. Flink 快速上手

1、创建项目导入依赖

pom文件：

<properties><flink.version>1.17.0</flink.version>
</properties><dependency><groupId>org.apache.flink</groupId><artifactId>flink-streaming-java</artifactId><version>${flink.version}</version>
</dependency>
<dependency><groupId>org.apache.flink</groupId><artifactId>flink-clients</artifactId><version>${flink.version}</version>
</dependency>

2、需求

批处理基本思路：先逐行读取文本，在根据空格进行单词拆分，最后再去统计每个单词出现的频率。

（1）数据准备

在工程目录下新建文件夹input，新建文本words.txt。

文件输入：

hello world
hello flink
hello java

2.1 批处理

代码编写（使用DataSet API实现）

java">package com.company.onedayflink.demo;import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.operators.AggregateOperator;
import org.apache.flink.api.java.operators.DataSource;
import org.apache.flink.api.java.operators.FlatMapOperator;
import org.apache.flink.api.java.operators.UnsortedGrouping;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;public class FlinkBatchWords {public static void main(String[] args) throws Exception {// 1、创建执行环境ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();// 2、从文件中读取数据DataSource<String> lineDS = env.readTextFile("one-day-flink/input/words.txt");// 3、切分、转换FlatMapOperator<String, Tuple2<String, Integer>> wordAndOne = lineDS.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {/**** @param value     读取到的输入* @param out       返回的内容，Tuple2是一个二元分组，（字符串，个数）。* @throws Exception*/@Overridepublic void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {// 3.1 切分for (String s : value.split(" ")) {// 3.2 将单组转为二元组Tuple2<String, Integer> tuple = Tuple2.of(s, 1);// 3.3 将二元组发送给下游out.collect(tuple);}}});// 4、按照 word 分组UnsortedGrouping<Tuple2<String, Integer>> wordAndOneGroup = wordAndOne.groupBy(0); // 0 表示下标为0的参数，也就是二元组的String单词// 5、各分组聚合AggregateOperator<Tuple2<String, Integer>> sum = wordAndOneGroup.sum(1);//1 表示下标1的元素，即单词个数// 6、输出sum.print();}
}

运行结果：

2.2 流处理

2.2.1 有界流

代码编写（使用DataStream API实现，读取文件属于有界流）

java">package com.company.onedayflink.demo;import lombok.extern.slf4j.Slf4j;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.KeyedStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.Collector;@Slf4j
public class FlinkStreamWords {public static void main(String[] args) throws Exception {// 1、创建执行环境StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();// 2、从文件中读取数据DataStreamSource<String> lineDS = env.readTextFile("one-day-flink/input/words.txt");// 3、处理数据（切换、转换、分组、聚合）// 3.1 切换、转换SingleOutputStreamOperator<Tuple2<String, Integer>> wordAndOne = lineDS.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {@Overridepublic void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {for (String s : value.split(" ")) {// 构建二元组Tuple2<String, Integer> tuple = Tuple2.of(s, 1);// 通过采集器向下游发送数据out.collect(tuple);}}});// 3.2 分组, KeySelector<IN, KEY> 中 IN 表示输入的类型，KEY 表示分组key的类型KeyedStream<Tuple2<String, Integer>, String> wordAndOneKS = wordAndOne.keyBy((KeySelector<Tuple2<String, Integer>, String>) value -> value.f0); // value.f0 表示二元组的第一个元素// 3.3 聚合SingleOutputStreamOperator<Tuple2<String, Integer>> sum = wordAndOneKS.sum(1);  // 1 表示二元组的第二个元素// 4、输出数据sum.print();// 5、执行env.execute();}
}

执行结果：

2> (java,1)
3> (hello,1)
3> (hello,2)
3> (hello,3)
6> (world,1)
8> (flink,1)

前面的编号是并行度，线程数。

2.2.2 无界流

（1）使用 netcat 监听7777端口，建立stream流

安装 netcat

brew install netcat

监听 7777 端口

nc -lk 7777

（2）代码编写（使用DataStream API实现，读取stream流属于无界流）

java">package com.company.onedayflink.demo;import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.typeinfo.Types;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.KeyedStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.Collector;public class FlinkSteamSocketWords {public static void main(String[] args) throws Exception {// 1、创建执行环境StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();// 2、读取数据（其中hostname 是需要监听的主机名称，mac电脑可以在终端使用hostname命令查看）DataStreamSource<String> socketDS = env.socketTextStream("zgyMacBook-Pro.local", 7777);// 3、数据处理（切割、转换、分组、聚合）SingleOutputStreamOperator<Tuple2<String, Integer>> sum = socketDS.flatMap((String value, Collector<Tuple2<String, Integer>> out) -> {// 3.1 切分for (String s : value.split(" ")) {// 3.2 将单组转为二元组Tuple2<String, Integer> tuple = Tuple2.of(s, 1);// 3.3 将二元组发送给下游out.collect(tuple);}}).returns(Types.TUPLE(Types.STRING, Types.INT)).keyBy(value -> value.f0).sum(1);// 4、输出sum.print();// 5、执行env.execute();}
}

（3）测试

在终端发送消息

hello flink
hello world

观察程序控制台打印

8> (flink,1)
3> (hello,1)
6> (world,1)
3> (hello,2)