本文主要是为Flink的java客户端使用和flink-sql使用的大致介绍，具体使用查看文档页面。

java client使用

文档

Apache Flink Documentation | Apache Flink

数据处理模型

maven依赖

<?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>org.example</groupId>
    <artifactId>flink_test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <!-- Apache Flink -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-java</artifactId>
            <version>1.15.4</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java</artifactId>
            <version>1.15.4</version>
        </dependency>
        <!-- Apache Flink -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-kafka</artifactId>
            <version>1.15.4</version>
        </dependency>

        <!-- Kafka Client -->
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
            <version>2.8.1</version>
        </dependency>

        <!--json-->
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20210307</version>
        </dependency>

        <!-- 解决 No ExecutorFactory found to execute the application-->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients</artifactId>
            <version>1.15.4</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-jdbc</artifactId>
            <version>1.15.4</version>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.25</version>
        </dependency>

    </dependencies>

<!--build fat jar-->
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.3.0</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>com.KafkaDataProcessor</mainClass>
                        </manifest>
                        <manifestEntries>
                            <Encoding>UTF-8</Encoding>
                        </manifestEntries>
                    </archive>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <compilerArgs>
                        <arg>-Xlint:unchecked</arg>
                        <arg>-Xlint:deprecation</arg>
                    </compilerArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

代码样例

读取kafka并打印结果

KafkaFlinkExample

import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;
import java.util.Properties;
public class KafkaFlinkExample {
    public static void main(String[] args) throws Exception {
        // 设置 Flink 程序的执行环境
        // StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.createLocalEnvironment();
        Properties props = new Properties();
        props.setProperty("bootstrap.servers", "192.168.10.153:9092");
        props.setProperty("group.id", "test");
        FlinkKafkaConsumer<String> consumer = new FlinkKafkaConsumer<>("input-topic", new SimpleStringSchema(), props);
        env.addSource(consumer)
                .map(data -> "Received: " + data)
                .print();
        env.execute("Kafka Flink Example");
    }
}

处理kafka数据并保存结果入新的topic

KafkaDataProcessor

import org.apache.flink.api.common.functions.MapFunction;
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.streaming.util.serialization.SimpleStringSchema;
import org.json.JSONObject;

import java.util.Properties;

public class KafkaDataProcessor {
    public static void main(String[] args) throws Exception {
        // 设置 Flink 程序的执行环境
//        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // 创建一个本地流执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.createLocalEnvironment();

        // 设置 Kafka 的配置信息
        Properties properties = new Properties();
        properties.setProperty("bootstrap.servers", "192.168.10.153:9092");
        properties.setProperty("group.id", "flink-consumer-group");

        // 创建 Kafka 消费者，并从指定的 topic 中读取数据
        FlinkKafkaConsumer<String> kafkaConsumer = new FlinkKafkaConsumer<>("input-topic", new SimpleStringSchema(), properties);
        DataStream<String> kafkaDataStream = env.addSource(kafkaConsumer);

        // 将 JSON 数据解析并添加性别字段
        DataStream<String> processedDataStream = kafkaDataStream.map(new MapFunction<String, String>() {
            @Override
            public String map(String value) throws Exception {
                // 解析 JSON 数据
                JSONObject jsonObject = new JSONObject(value);
                String name = jsonObject.getString("name");
                int id = jsonObject.getInt("id");
                int age = jsonObject.getInt("age");

                // 根据姓名判断性别
                String gender;
                if (name.equals("jack")) {
                    gender = "male_xxx";
                } else {
                    gender = "female_xxx";
                }

                // 构造新的 JSON 数据
                JSONObject newJsonObject = new JSONObject();
                newJsonObject.put("name", name);
                newJsonObject.put("id", id);
                newJsonObject.put("age", age);
                newJsonObject.put("gender", gender);
                return newJsonObject.toString();
            }
        });

        // 创建 Kafka 生产者，并将新的数据写入指定的 topic
        FlinkKafkaProducer<String> kafkaProducer = new FlinkKafkaProducer<>("output-topic", new SimpleStringSchema(), properties);
        processedDataStream.addSink(kafkaProducer);
        // 执行程序
        env.execute("Kafka Data Processor");
    }
}

设置执行并行度

LocalWebUI

import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.datastream.DataStreamSink;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;

import java.util.Properties;

public class LocalWebUI {
    public static void main(String[] args) throws Exception {
        //StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        Configuration configuration = new Configuration();
        //创建一个带webUI的本地执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.createLocalEnvironmentWithWebUI(configuration);
        int parallelism = env.getParallelism();

        Properties props = new Properties();
        props.setProperty("bootstrap.servers", "192.168.10.153:9092");
        props.setProperty("group.id", "test");
        FlinkKafkaConsumer<String> consumer = new FlinkKafkaConsumer<>("input-topic", new SimpleStringSchema(), props);

        System.out.println("执行环境的并行度：" + parallelism);
//        DataStreamSource<String> lines = env.socketTextStream("localhost", 8888);

        DataStreamSource<String> lines = env.addSource(consumer);

        int parallelism1 = lines.getParallelism();
        System.out.println("socketTextStream创建的DataStreamSource的并行度：" + parallelism1);
        SingleOutputStreamOperator<String> uppered = lines.map(line -> line.toUpperCase());
        int parallelism2 = uppered.getParallelism();
        System.out.println("调用完map方法得到的DataStream的并行度：" + parallelism2);
        DataStreamSink<String> print = uppered.print();
        int parallelism3 = print.getTransformation().getParallelism();
        System.out.println("调用完print方法得到的DataStreamSink的并行度：" + parallelism3);
        env.execute();
    }
}

本地执行

Flink可以和Spark类似，开发过程中，在本地临时执行，需要两个条件

1.需要flink-client依赖引入，否则会报No ExecutorFactory found to execute the application

<dependency>
    <groupId>org.apache.flink</groupId>
    <artifactId>flink-clients</artifactId>
    <version>1.15.4</version>
</dependency>

2.设置flink的执行环境

StreamExecutionEnvironment env = StreamExecutionEnvironment.createLocalEnvironment();

集群执行

打包

mvn clean package

提交任务

flink run -c com.KafkaDataProcessor /root/flink_test-1.0-SNAPSHOT-jar-with-dependencies.jar

观察任务状态

Job---->>Running Jobs

结束任务

Job---->>Running Jobs--->>点击任务---->>Cannel Job

flink-sql

文档

https://nightlies.apache.org/flink/flink-docs-release-1.14/zh/docs/dev/table/common/

启动客户端

cd /root/flink-1.15.4/bin

./sql-client.sh

需求案例

汇总kafka数据，将结果保存入mysql中

依赖准备

mysql版本是8.0.25，flink版本是1.15.4，connector的版本一定要和flink版本保持一致。所有集群节点的lib一定要保持一致然后重启。

依赖下载位置：Central Repository:

mysql-connector-java-8.0.25.jar
flink-connector-jdbc-1.15.4.jar
kafka-clients-2.8.1.jar
flink-connector-kafka-1.15.4.jar

准备结果表

CREATE TABLE sync_test_1 (
  `day_time` varchar(64) NOT NULL,
  `total_gmv` bigint(11) DEFAULT NULL,
  PRIMARY KEY (`day_time`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4;

sql配置

create table flink_test_1 ( 
  id BIGINT,
  day_time VARCHAR,
  amnount BIGINT,
  proctime AS PROCTIME ()
)
 with ( 
  'connector' = 'kafka',
  'topic' = 'flink_test',
  'properties.bootstrap.servers' = '192.168.10.153:9092', 
  'properties.group.id' = 'flink_gp_test1',
  'scan.startup.mode' = 'earliest-offset',
  'format' = 'json',
  'json.fail-on-missing-field' = 'false',
  'json.ignore-parse-errors' = 'true',
  'properties.zookeeper.connect' = '192.168.10.153:2181/kafka'
 );

CREATE TABLE sync_test_1 (
                   day_time string,
                   total_gmv bigint,
                   PRIMARY KEY (day_time) NOT ENFORCED
 ) WITH (
   'connector' = 'jdbc',
   'url' = 'jdbc:mysql://192.168.10.151:3306/flink_web?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=false',
   'table-name' = 'sync_test_1',
   'username' = 'root',
   'password' = '123456'
 );

INSERT INTO sync_test_1 
SELECT day_time,SUM(amnount) AS total_gmv
FROM flink_test_1
GROUP BY day_time;