【Flink】二、数据源：DataStreamSource_flink datastreamsource

前言

本篇来聊聊flink支持哪些数据源。

1 集合

• fromCollection：从集合或迭代器中获取数据流，集合或迭代器内元素类型相同

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
DataStream<NetConnectEvent> eventStream = env.fromCollection(Arrays.asList(
	new NetConnectEvent("192.168.27.63","192.168.27.1",true),
	new NetConnectEvent("192.168.27.64","192.168.27.2",false)
));

• fromElements：本质上还是fromCollection

public final <OUT> DataStreamSource<OUT> fromElements(OUT... data) {
	if (data.length == 0) {
	    throw new IllegalArgumentException("fromElements needs at least one element as argument");
	} else {
	    TypeInformation typeInfo;
	    try {
		typeInfo = TypeExtractor.getForObject(data[0]);
	    } catch (Exception var4) {
		throw new RuntimeException("Could not create TypeInformation for type " + data[0].getClass().getName() + "; please specify the TypeInformation manually via StreamExecutionEnvironment#fromElements(Collection, TypeInformation)", var4);
	    }
 
	    return this.fromCollection((Collection)Arrays.asList(data), (TypeInformation)typeInfo);
	}
}

• generateSequence：生成某个范围内随机数字（Long）序列

StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
DataStreamSource<Long> dataStreamSource = environment.generateSequence(1L,10L);

2 文件

• readFile：读取文件，可自定义文件内容格式
• readTextFile：本质上就是readFile，只是文件要满足TextInputFormat规范，按行读取返回字符串

StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
environment.readTextFile("D:\\test.txt")

3 套接字

• socketTextStream：从socket中获取数据流，一般测试用，因为socket无状态无法保证可靠性且是单线程

StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
environment.socketTextStream("127.0.0.1",9999)

4 自定义

• 实现SourceFunction

一般来说会直接扩展RichParallelSourceFunction来自定义数据源。

class TestSource implements SourceFunction<String> {
 
	private volatile boolean isRunning = true;
 
	@Override
	public void run(SourceContext<Tuple2<Integer, Integer>> ctx) throws Exception {
		while (isRunning) {
			ctx.collect("some string");
			Thread.sleep(1L);
		}
	}
 
	@Override
	public void cancel() {
		isRunning = false;
	}
}

• Kafka数据源：FlinkKafkaConsumer本质上也是实现了SourceFunction

StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
Properties properties = new Properties();
properties.setProperty("bootstrap.servers", "10.20.178.243:9092");
DataStreamSource<String> dataStreamSource = environment.addSource(new FlinkKafkaConsumer<>("flink",new SimpleStringSchema(), properties));
dataStreamSource.print();
environment.execute("KafkaDataSourceTest");

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