Structured Streaming 实战案例 读取文本数据

1.1.1.读取文本数据

spark应用可以监听某一个目录，而web服务在这个目录上实时产生日志文件，这样对于spark应用来说，日志文件就是实时数据

Structured Streaming支持的文件类型有text，csv，json，parquet

●准备工作

在people.json文件输入如下数据:

{"name":"json","age":23,"hobby":"running"}

{"name":"charles","age":32,"hobby":"basketball"}

{"name":"tom","age":28,"hobby":"football"}

{"name":"lili","age":24,"hobby":"running"}

{"name":"bob","age":20,"hobby":"swimming"}

注意:文件必须是被移动到目录中的，且文件名不能有特殊字符

●需求

接下里使用Structured Streaming统计年龄小于25岁的人群的爱好排行榜

●代码演示：

import org.apache.spark.SparkContext
import org.apache.spark.sql.streaming.Trigger
import org.apache.spark.sql.types.StructType
import org.apache.spark.sql.{DataFrame, Dataset, Row, SparkSession}
/**
  * {"name":"json","age":23,"hobby":"running"}
  * {"name":"charles","age":32,"hobby":"basketball"}
  * {"name":"tom","age":28,"hobby":"football"}
  * {"name":"lili","age":24,"hobby":"running"}
  * {"name":"bob","age":20,"hobby":"swimming"}
  * 统计年龄小于25岁的人群的爱好排行榜
  */
object WordCount2 {
  def main(args: Array[String]): Unit = {
    //1.创建SparkSession,因为StructuredStreaming的数据模型也是DataFrame/DataSet
    val spark: SparkSession = SparkSession.builder().master("local[*]").appName("SparkSQL").getOrCreate()
    val sc: SparkContext = spark.sparkContext
    sc.setLogLevel("WARN")
    val Schema: StructType = new StructType()
      .add("name","string")
      .add("age","integer")
      .add("hobby","string")
    //2.接收数据
    import spark.implicits._
    // Schema must be specified when creating a streaming source DataFrame.
    val dataDF: DataFrame = spark.readStream.schema(Schema).json("D:\\data\\spark\\data")
    //3.处理数据
    val result: Dataset[Row] = dataDF.filter($"age" < 25).groupBy("hobby").count().sort($"count".desc)
    //4.输出结果
    result.writeStream
      .format("console")
      .outputMode("complete")
      .trigger(Trigger.ProcessingTime(0))
      .start()
      .awaitTermination()
  }
}

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import org.apache.spark.SparkContext

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import org.apache.spark.sql.streaming.Trigger

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import org.apache.spark.sql.types.StructType

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import org.apache.spark.sql.{DataFrame, Dataset, Row, SparkSession}

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/**

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  * {"name":"json","age":23,"hobby":"running"}

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  * {"name":"charles","age":32,"hobby":"basketball"}

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  * {"name":"tom","age":28,"hobby":"football"}

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  * {"name":"lili","age":24,"hobby":"running"}

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  * {"name":"bob","age":20,"hobby":"swimming"}

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  * 统计年龄小于25岁的人群的爱好排行榜

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  */

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object WordCount2 {

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  def main(args: Array[String]): Unit = {

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    //1.创建SparkSession,因为StructuredStreaming的数据模型也是DataFrame/DataSet

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    val spark: SparkSession = SparkSession.builder().master("local[*]").appName("SparkSQL").getOrCreate()

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    val sc: SparkContext = spark.sparkContext

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    sc.setLogLevel("WARN")

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    val Schema: StructType = new StructType()

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      .add("name","string")

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      .add("age","integer")

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      .add("hobby","string")

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    //2.接收数据

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    import spark.implicits._

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    // Schema must be specified when creating a streaming source DataFrame.

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    val dataDF: DataFrame = spark.readStream.schema(Schema).json("D:\\data\\spark\\data")

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    //3.处理数据

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    val result: Dataset[Row] = dataDF.filter($"age" < 25).groupBy("hobby").count().sort($"count".desc)

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    //4.输出结果

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    result.writeStream

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      .format("console")

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      .outputMode("complete")

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      .trigger(Trigger.ProcessingTime(0))

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      .start()

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      .awaitTermination()

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  }

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}

代码截图：

原文地址：https://www.cnblogs.com/TiePiHeTao/p/e83029055db1b4a602e15785b2d079c1.html