Java版Flink使用指南——从RabbitMQ中队列中接入消息流

大纲

• 创建RabbitMQ队列
• 新建工程
• • 新增依赖
  • 编码
  • • 设置数据源配置
    • 读取、处理数据
    • 完整代码
  • 打包、上传和运行任务
  • 测试
• 工程代码

在《Java版Flink使用指南------安装Flink和使用IntelliJ制作任务包》一文中，我们完成了第一个小型Demo的编写。例子中的数据是代码预先指定的。而现实中，数据往往来源于外部。本文我们将尝试Flink从RabbitMQ中读取数据，然后输出到日志中。

关于RabbitMQ的知识可以参阅《RabbitMQ实践》。

创建RabbitMQ队列

我们创建一个Classic队列data.from.rbtmq。注意要选择Durable类型，这是后续用的默认连接器的限制。

具体方法见《RabbitMQ实践------在管理后台测试消息收发功能》。

后续我们将在后台通过默认交换器，给这个队列新增消息。

新建工程

我们在IntelliJ中新建一个工程DataFromRabbitMQ。

Archetype填入：org.apache.flink:flink-quickstart-java。

版本填入与Flink的版本：1.19.1

新增依赖

在pom.xml中新增RabbitMQ连接器

<dependency>
	<groupId>org.apache.flink</groupId>
	<artifactId>flink-connector-rabbitmq</artifactId>
	<version>3.0.1-1.17</version>
</dependency>

编码

设置数据源配置

String queueName = "data.from.rbtmq";
String host = "172.21.112.140"; // IP of the rabbitmq server
int port = 5672;
String username = "admin";
String password = "fangliang";
String virtualHost = "/";
int parallelism = 1;

// create a RabbitMQ source
RMQConnectionConfig rmqConnectionConfig = new RMQConnectionConfig.Builder()
		.setHost(host)
		.setPort(port)
		.setUserName(username)
		.setPassword(password)
		.setVirtualHost(virtualHost)
		.build();

RMQSource<String> rmqSource = new RMQSource<>(rmqConnectionConfig, queueName, true, new SimpleStringSchema());

读取、处理数据

下面代码通过addSource添加RabbitMQ数据源。注意，不能使用fromSource方法，是因为RMQSource没有实现SourceFunction方法。

final DataStream<String> stream = env.addSource(rmqSource).name(username + "'s source from " + queueName).setParallelism(parallelism);

stream.print().name(username + "'s data from " + queueName);

完整代码

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.example;

import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.rabbitmq.RMQSource;
import org.apache.flink.streaming.connectors.rabbitmq.common.RMQConnectionConfig;

/**
 * Skeleton for a Flink DataStream Job.
 *
 * <p>For a tutorial how to write a Flink application, check the
 * tutorials and examples on the <a href="https://flink.apache.org">Flink Website</a>.
 *
 * <p>To package your application into a JAR file for execution, run
 * 'mvn clean package' on the command line.
 *
 * <p>If you change the name of the main class (with the public static void main(String[] args))
 * method, change the respective entry in the POM.xml file (simply search for 'mainClass').
 */
public class DataStreamJob {

	public static void main(String[] args) throws Exception {
		// Sets up the execution environment, which is the main entry point
		// to building Flink applications.
		final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

		String queueName = "data.from.rbtmq";
		String host = "172.21.112.140"; // IP of the rabbitmq server
		int port = 5672;
		String username = "admin";
		String password = "fangliang";
		String virtualHost = "/";
		int parallelism = 1;

		// create a RabbitMQ source
		RMQConnectionConfig rmqConnectionConfig = new RMQConnectionConfig.Builder()
				.setHost(host)
				.setPort(port)
				.setUserName(username)
				.setPassword(password)
				.setVirtualHost(virtualHost)
				.build();

		RMQSource<String> rmqSource = new RMQSource<>(rmqConnectionConfig, queueName, true, new SimpleStringSchema());
		final DataStream<String> stream = env.addSource(rmqSource).name(username + "'s source from " + queueName).setParallelism(parallelism);

		stream.print().name(username + "'s data from " + queueName);

		env.execute("Flink Java API Skeleton");
	}
}

打包、上传和运行任务

测试

在RabbitMQ后台的默认交换器中，发布一条消息到data.from.rbtmq

然后使用下面指令可以看到Flink读取到消息并执行了print方法

tail log/flink-*-taskexecutor-*.out

==> flink-fangliang-taskexecutor-0-fangliang.out <==

data from http://172.21.112.140:15672/#/exchanges/%2F/amq.default

工程代码

https://github.com/f304646673/FlinkDemo