【实战-08】flink 消费kafka自定义序列化

目的

让从kafka消费出来的数据，直接就转换成我们的对象

mvn pom

java 复制代码

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<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.boke</groupId>
	<artifactId>Flink1.7.1</artifactId>
	<version>1.0-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>Flink Quickstart Job</name>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<flink.version>1.17.1</flink.version>
		<target.java.version>1.8</target.java.version>
		<scala.binary.version>2.12</scala.binary.version>
		<maven.compiler.source>${target.java.version}</maven.compiler.source>
		<maven.compiler.target>${target.java.version}</maven.compiler.target>
		<log4j.version>2.17.1</log4j.version>
	</properties>

	<repositories>
		<repository>
			<id>apache.snapshots</id>
			<name>Apache Development Snapshot Repository</name>
			<url>https://repository.apache.org/content/repositories/snapshots/</url>
			<releases>
				<enabled>false</enabled>
			</releases>
			<snapshots>
				<enabled>true</enabled>
			</snapshots>
		</repository>
	</repositories>

	<dependencies>
		<!-- Apache Flink dependencies -->
		<!-- These dependencies are provided, because they should not be packaged into the JAR file. -->
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-streaming-java</artifactId>
			<version>${flink.version}</version>
<!--			<scope>provided</scope>-->
		</dependency>
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-clients</artifactId>
			<version>${flink.version}</version>
<!--			<scope>provided</scope>-->
		</dependency>
		<!-- table 环境依赖【connectors 和 formats 和driver】 https://nightlies.apache.org/flink/flink-docs-release-1.17/docs/dev/configuration/overview/		-->
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-connector-kafka</artifactId>
			<version>${flink.version}</version>
		</dependency>
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-table-api-java</artifactId>
			<version>${flink.version}</version>
<!--			<scope>provided</scope>-->
		</dependency>
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-table-api-java-bridge</artifactId>
			<version>${flink.version}</version>
<!--			<scope>provided</scope>-->
		</dependency>
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-connector-jdbc</artifactId>
			<version>3.1.0-1.17</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.18</version>
		</dependency>
		<!--idea 运行比西甲这个否则报错：【 Make sure a planner module is on the classpath】-->
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-table-planner-loader</artifactId>
			<version>${flink.version}</version>
			<!--			<scope>provided</scope>-->
		</dependency>
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-table-runtime</artifactId>
			<version>${flink.version}</version>
			<!--			<scope>provided</scope>-->
		</dependency>
		<!--第三方的包-->
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>fastjson</artifactId>
			<version>1.2.83</version>
		</dependency>
		<!-- Add connector dependencies here. They must be in the default scope (compile). -->

		<!-- Example:

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

		<!-- Add logging framework, to produce console output when running in the IDE. -->
		<!-- These dependencies are excluded from the application JAR by default. -->
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-slf4j-impl</artifactId>
			<version>${log4j.version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-api</artifactId>
			<version>${log4j.version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-core</artifactId>
			<version>${log4j.version}</version>
			<scope>runtime</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>

			<!-- Java Compiler -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
					<source>${target.java.version}</source>
					<target>${target.java.version}</target>
				</configuration>
			</plugin>

			<!-- We use the maven-shade plugin to create a fat jar that contains all necessary dependencies. -->
			<!-- Change the value of <mainClass>...</mainClass> if your program entry point changes. -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-shade-plugin</artifactId>
				<version>3.1.1</version>
				<executions>
					<!-- Run shade goal on package phase -->
					<execution>
						<phase>package</phase>
						<goals>
							<goal>shade</goal>
						</goals>
						<configuration>
							<createDependencyReducedPom>false</createDependencyReducedPom>
							<artifactSet>
								<excludes>
									<exclude>org.apache.flink:flink-shaded-force-shading</exclude>
									<exclude>com.google.code.findbugs:jsr305</exclude>
									<exclude>org.slf4j:*</exclude>
									<exclude>org.apache.logging.log4j:*</exclude>
								</excludes>
							</artifactSet>
							<filters>
								<filter>
									<!-- Do not copy the signatures in the META-INF folder.
									Otherwise, this might cause SecurityExceptions when using the JAR. -->
									<artifact>*:*</artifact>
									<excludes>
										<exclude>META-INF/*.SF</exclude>
										<exclude>META-INF/*.DSA</exclude>
										<exclude>META-INF/*.RSA</exclude>
									</excludes>
								</filter>
							</filters>
							<transformers>
								<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
								<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
									<mainClass>com.boke.DataStreamJob</mainClass>
								</transformer>
							</transformers>
						</configuration>
					</execution>
				</executions>
			</plugin>
		</plugins>

		<pluginManagement>
			<plugins>

				<!-- This improves the out-of-the-box experience in Eclipse by resolving some warnings. -->
				<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-shade-plugin</artifactId>
										<versionRange>[3.1.1,)</versionRange>
										<goals>
											<goal>shade</goal>
										</goals>
									</pluginExecutionFilter>
									<action>
										<ignore/>
									</action>
								</pluginExecution>
								<pluginExecution>
									<pluginExecutionFilter>
										<groupId>org.apache.maven.plugins</groupId>
										<artifactId>maven-compiler-plugin</artifactId>
										<versionRange>[3.1,)</versionRange>
										<goals>
											<goal>testCompile</goal>
											<goal>compile</goal>
										</goals>
									</pluginExecutionFilter>
									<action>
										<ignore/>
									</action>
								</pluginExecution>
							</pluginExecutions>
						</lifecycleMappingMetadata>
					</configuration>
				</plugin>
			</plugins>
		</pluginManagement>
	</build>
</project>

核心代码

package com.boke.kafka;

import com.alibaba.fastjson.JSONObject;

public class Student {

public String name;

public Integer age;

复制代码

public Student(String name, Integer age) {
    this.name = name;
    this.age = age;
}

public static Student fromJson(String s){
    JSONObject jsonObject = JSONObject.parseObject(s);
    String name = jsonObject.getString("name");
    Integer age = jsonObject.getInteger("age");
    return new Student(name,age);
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public Integer getAge() {
    return age;
}

public void setAge(Integer age) {
    this.age = age;
}

}

//下面是main主函数

package com.boke.kafka;

import org.apache.flink.api.common.eventtime.WatermarkStrategy;

import org.apache.flink.api.common.typeinfo.TypeHint;

import org.apache.flink.api.common.typeinfo.TypeInformation;

import org.apache.flink.connector.kafka.source.KafkaSource;

import org.apache.flink.connector.kafka.source.enumerator.initializer.OffsetsInitializer;

import org.apache.flink.connector.kafka.source.reader.deserializer.KafkaRecordDeserializationSchema;

import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

import org.apache.flink.streaming.connectors.kafka.KafkaDeserializationSchema;

import org.apache.kafka.clients.consumer.ConsumerRecord;

import java.nio.charset.StandardCharsets;

public class kafkaSource {

public static void main(String[] args) {

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

KafkaSource source = KafkaSource.builder()

.setBootstrapServers("brokers")

.setTopics("input-topic")

.setGroupId("my-group")

.setStartingOffsets(OffsetsInitializer.earliest())//【无论如何都从最早开始消费】

// .setStartingOffsets(OffsetsInitializer.latest())//【无论如何都从最新开始消费】

// .setStartingOffsets(OffsetsInitializer.committedOffsets(OffsetResetStrategy.EARLIEST))//【groupid 存在offset 则从offset消费，否则从最早开始消费】

// .setStartingOffsets(OffsetsInitializer.committedOffsets(OffsetResetStrategy.LATEST))//【groupid 存在offset 则从offset消费，否则从最新开始消费】

// .setDeserializer(KafkaRecordDeserializationSchema.of(new KafkaDeserializationSchemaWrapper<>(new SimpleStringSchema())))

// .setDeserializer(KafkaRecordDeserializationSchema.of(new SimpleStringSchema());

.setDeserializer(KafkaRecordDeserializationSchema.of(new MyKafkaDeserializationSchema()))

// .setDeserializer(KafkaRecordDeserializationSchema.valueOnly())

.build();

复制代码

    env.fromSource(source, WatermarkStrategy.noWatermarks(), "Kafka Source");
}

}

class MyKafkaDeserializationSchema implements KafkaDeserializationSchema{

复制代码

@Override
public boolean isEndOfStream(Student nextElement) {
    return false;
}

//Deserializes the Kafka record.

//Params:

//record -- Kafka record to be deserialized.

//Returns:

//The deserialized message as an object (null if the message cannot be deserialized).

@Override

public Student deserialize(ConsumerRecord<byte[], byte[]> record) throws Exception {

*自定义kafka反序列化

*如果数据异常，可以直接返回nulll即可，源码中有一句英文：null if the message cannot be deserialized

* */

String topic = record.topic();

long KafkaTimeStamp = record.timestamp();

int partitionNum = record.partition();

String value = new String(record.value(), StandardCharsets.UTF_8);

return Student.fromJson(value);

}

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@Override
public TypeInformation<Student> getProducedType() {
    return TypeInformation.of(new TypeHint<Student>() {});
}

}