Flink中source数据源整理汇总

Flink中source数据源整理汇总

1. 从集合创建

// 定义样例类，传感器id，时间戳，温度
case class SensorReading(id: String, timestamp: Long, temperature: Double)

object Sensor {
  def main(args: Array[String]): Unit = {
    val env = StreamExecutionEnvironment.getExecutionEnvironment
    val stream1 = env
      .fromCollection(List(
        SensorReading("sensor_1", 1547718199, 35.8),
        SensorReading("sensor_6", 1547718201, 15.4),
        SensorReading("sensor_7", 1547718202, 6.7),
        SensorReading("sensor_10", 1547718205, 38.1)
      ))

    stream1.print("stream1:").setParallelism(1)

    env.execute()
  }
}

2. 从文件读取数据

val stream2 = env.readTextFile("YOUR_FILE_PATH")

3. 以kafka消息队列的数据作为来源
   需要引入kafka连接器的依赖

<!-- https://mvnrepository.com/artifact/org.apache.flink/flink-connector-kafka-0.11 -->
>
    >org.apache.flink>
    >flink-connector-kafka-0.11_2.11>
    >1.10.0>
>

具体代码如下：

val properties = new Properties()
properties.setProperty("bootstrap.servers", "localhost:9092")
properties.setProperty("group.id", "consumer-group")
properties.setProperty("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer")
properties.setProperty("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer")
properties.setProperty("auto.offset.reset", "latest")

val stream3 = env.addSource(new FlinkKafkaConsumer011[String]("sensor", new SimpleStringSchema(), properties))

4. 自定义数据源
   除了以上的source数据来源，我们还可以自定义source。需要做的，只是传入一个SourceFunction就可以。具体调用如下：

val stream4 = env.addSource( new MySensorSource() )

我们希望可以随机生成传感器数据，MySensorSource具体的代码实现如下：

class MySensorSource extends SourceFunction[SensorReading]{

// flag: 表示数据源是否还在正常运行
var running: Boolean = true

override def cancel(): Unit = {
running = false
}

override def run(ctx: SourceFunction.SourceContext[SensorReading]): Unit = {
// 初始化一个随机数发生器
val rand = new Random()

var curTemp = 1.to(10).map(
i => ( "sensor_" + i, 65 + rand.nextGaussian() * 20 )
)

while(running){
// 更新温度值
curTemp = curTemp.map(
t => (t._1, t._2 + rand.nextGaussian() )
)
// 获取当前时间戳
val curTime = System.currentTimeMillis()

curTemp.foreach(
t => ctx.collect(SensorReading(t._1, curTime, t._2))
)
Thread.sleep(100)
}
}
}