Flink Table读取外部数据(File、Kafka)以及查询转换

时间:2021-01-12
本文章向大家介绍Flink Table读取外部数据(File、Kafka)以及查询转换,主要包括Flink Table读取外部数据(File、Kafka)以及查询转换使用实例、应用技巧、基本知识点总结和需要注意事项,具有一定的参考价值,需要的朋友可以参考一下。

知识点

FlinkTable步骤:
  // 1、创建表的执行环境 
  val tableEnv = ... 
  // 2、创建一张表,用于读取数据 
  tableEnv.connect(...).createTemporaryTable("inputTable") 
  // 3、1通过 Table API 查询算子,得到一张结果表 
  val result = tableEnv.from("inputTable").select(...) 
  // 3、2通过 SQL 查询语句,得到一张结果表 
  val sqlResult = tableEnv.sqlQuery("SELECT ... FROM inputTable ...") 
  // 4、注册一张表,用于把计算结果输出 
  tableEnv.connect(...).createTemporaryTable("outputTable") 
  // 5、将结果表写入输出表中 
  result.insertInto("outputTable")

1、CSV文件依赖

    <dependency>
      <groupId>org.apache.flink</groupId>
      <artifactId>flink-csv</artifactId>
      <version>1.10.1</version>
    </dependency>

2、代码案例

package table

import org.apache.flink.api.scala.ExecutionEnvironment
import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment
import org.apache.flink.table.api.{DataTypes, EnvironmentSettings, Table, TableEnvironment}
import org.apache.flink.table.api.scala.{BatchTableEnvironment, StreamTableEnvironment}
import org.apache.flink.table.descriptors.{Csv, FileSystem, Kafka, OldCsv, Schema}
import org.apache.flink.table.api.scala._
import org.apache.flink.streaming.api.scala._
/**
 * @author yangwj
 * @date 2021/1/12 21:53
 * @version 1.0
 */
object TableApiTest {
  def main(args: Array[String]): Unit = {
    //1、创建表执行环境、就得使用流式环境
    val env: StreamExecutionEnvironment = StreamExecutionEnvironment.getExecutionEnvironment
    env.setParallelism(1)

    val tableEnv: StreamTableEnvironment = StreamTableEnvironment.create(env)
/**
    //1、1老版本planner的流处理
    val setttings = EnvironmentSettings.newInstance()
      .useOldPlanner()
      .inStreamingMode()
      .build()
    val oldStreamTableEnv: StreamTableEnvironment = StreamTableEnvironment.create(env, setttings)
    //1.2老版本的批处理
    val batchEnv = ExecutionEnvironment.getExecutionEnvironment
    val oldBatchTableEnv: BatchTableEnvironment = BatchTableEnvironment.create(batchEnv)

    //1.1新版本,基于blink planner的流处理
    val blinkStreamSettings: EnvironmentSettings = EnvironmentSettings.newInstance()
      .useBlinkPlanner()
      .inStreamingMode()
      .build()
    val blinkStreamTableEnv = StreamTableEnvironment.create(env,blinkStreamSettings)

    //1.2新版本,基于blink planner的批处理
    val blinkBatchSettings: EnvironmentSettings = EnvironmentSettings.newInstance()
      .useBlinkPlanner()
      .inBatchMode()
      .build()
    val blinkBatchTableEnv = TableEnvironment.create(blinkBatchSettings)

  **/
    //2、连接外部系统,读取数据,注册表
    //2.1读取文件
    val inputFile:String = "G:\\Java\\Flink\\guigu\\flink\\src\\main\\resources\\sensor.txt"
    tableEnv.connect(new FileSystem().path(inputFile))
      // new OldCsv()是一个非标的格式描述
      .withFormat(new Csv())
      .withSchema(new Schema().field("id",DataTypes.STRING())
      .field("timestamp",DataTypes.BIGINT())
      .field("temperature",DataTypes.DOUBLE())
      )
      .createTemporaryTable("inputTable")

    val inputTable: Table = tableEnv.from("inputTable")
    inputTable.toAppendStream[(String,Long,Double)].print("result")


    //2.2读取kafka数据
    tableEnv.connect(new Kafka()
    .version("0.11")
    .topic("Demo")
    .property("zookeeper.connect","localhost:2181")
    .property("bootstrap.servers","localhost:9092")
    )
        .withFormat(new Csv())
        .withSchema(new Schema().field("id",DataTypes.STRING())
          .field("timestamp",DataTypes.BIGINT())
          .field("temperature",DataTypes.DOUBLE())
        ).createTemporaryTable("kafkaTable")

    val kafkaTable: Table = tableEnv.from("kafkaTable")
    kafkaTable.toAppendStream[(String,Long,Double)].print("kafkaResult")


    //3、查询转换
    //3.1 使用table api
    val sensorTable: Table = tableEnv.from("inputTable")
    val apiResult: Table = sensorTable.select('id, 'temperature)
      .filter('id === "sensor_1")

    //3.2sql实现
    val sqlResult: Table = tableEnv.sqlQuery(
      """
        |select id ,temperature
        |from inputTable
        |where id = 'sensor_1'
        """.stripMargin)

    apiResult.toAppendStream[(String, Double)].print("apiResult")
    sqlResult.toAppendStream[(String, Double)].print("sqlResult")
    env.execute("table api test")
  }

}