Spark创建DataFrame的几种方式

左手的ㄟ右手 2023-02-11 04:46 53阅读 0赞

参考文章：[Spark创建DataFrame的几种方式][Spark_DataFrame]

要生成如下的DataFrame数据

+----+---+-----------+
    |name|age|      phone|
    +----+---+-----------+
    |ming| 20|15552211521|
    |hong| 19|13287994007|
    | zhi| 21|15552211523|
    +----+---+-----------+

### 第一种：通过Seq生成 ###

val spark = SparkSession
      .builder()
      .appName(this.getClass.getSimpleName).master("local")
      .getOrCreate()
    
    val df = spark.createDataFrame(Seq(
      ("ming", 20, 15552211521L),
      ("hong", 19, 13287994007L),
      ("zhi", 21, 15552211523L)
    )) toDF("name", "age", "phone")
    
    df.show()

### 第二种：读取Json文件生成 ###

**json文件内容**

{"name":"ming","age":20,"phone":15552211521}
    {"name":"hong", "age":19,"phone":13287994007}
    {"name":"zhi", "age":21,"phone":15552211523}

**代码**

val dfJson = spark.read.format("json")
    .load("/Users/shirukai/Desktop/HollySys/Repository/sparkLearn/data/student.json")
    
    dfJson.show()

### 第三种：读取csv文件生成 ###

**csv文件**

name,age,phone
    ming,20,15552211521
    hong,19,13287994007
    zhi,21,15552211523

**代码**

val dfCsv = spark.read.format("csv")
    .option("header", true)
    .load("/Users/shirukai/Desktop/HollySys/Repository/sparkLearn/data/students.csv")
    
    dfCsv.show()

### 第四种：通过Json格式的RDD生成（弃用） ###

val sc = spark.sparkContext
    import spark.implicits._
    val jsonRDD = sc.makeRDD(Array(
      "{\"name\":\"ming\",\"age\":20,\"phone\":15552211521}",
      "{\"name\":\"hong\", \"age\":19,\"phone\":13287994007}",
      "{\"name\":\"zhi\", \"age\":21,\"phone\":15552211523}"
    ))
    
    val jsonRddDf = spark.read.json(jsonRDD)
    jsonRddDf.show()

### 第五种：通过Json格式的DataSet生成 ###

val jsonDataSet = spark.createDataset(Array(
      "{\"name\":\"ming\",\"age\":20,\"phone\":15552211521}",
      "{\"name\":\"hong\", \"age\":19,\"phone\":13287994007}",
      "{\"name\":\"zhi\", \"age\":21,\"phone\":15552211523}"
    ))
    val jsonDataSetDf = spark.read.json(jsonDataSet)
    
    jsonDataSetDf.show()

### 第六种: 通过csv格式的DataSet生成 ###

val scvDataSet = spark.createDataset(Array(
      "ming,20,15552211521",
      "hong,19,13287994007",
      "zhi,21,15552211523"
    ))
    spark.read.csv(scvDataSet).toDF("name","age","phone").show()

### 第七种：动态创建schema ###

val schema = StructType(List(
      StructField("name", StringType, true),
      StructField("age", IntegerType, true),
      StructField("phone", LongType, true)
    ))
    val dataList = new util.ArrayList[Row]()
    dataList.add(Row("ming",20,15552211521L))
    dataList.add(Row("hong",19,13287994007L))
    dataList.add(Row("zhi",21,15552211523L))
    spark.createDataFrame(dataList,schema).show()

### 第八种：通过jdbc创建 ###

//第八种：读取数据库（mysql）
    val options = new util.HashMap[String,String]()
    options.put("url", "jdbc:mysql://localhost:3306/spark")
    options.put("driver","com.mysql.jdbc.Driver")
    options.put("user","root")
    options.put("password","hollysys")
    options.put("dbtable","user")
    
    spark.read.format("jdbc").options(options).load().show()

### 完整代码 ###

package com.hollysys.spark
    
    import java.util
    
    import org.apache.spark.sql.types._
    import org.apache.spark.sql.{Row, SQLContext, SparkSession}
    
    /**
      * Created by shirukai on 2018/7/17
      * 创建DataFrame的几种方式
      */
    object CreateDataFrameTest {
      def main(args: Array[String]): Unit = {
        val spark = SparkSession
          .builder()
          .appName(this.getClass.getSimpleName).master("local")
          .getOrCreate()
    
        //第一种：通过Seq生成
        val df = spark.createDataFrame(Seq(
          ("ming", 20, 15552211521L),
          ("hong", 19, 13287994007L),
          ("zhi", 21, 15552211523L)
        )) toDF("name", "age", "phone")
    
        df.show()
    
        //第二种：通过读取Json文件生成
        val dfJson = spark.read.format("json")
        .load("/Users/shirukai/Desktop/HollySys/Repository/sparkLearn/data/student.json")
        
        dfJson.show()
    
        //第三种：通过读取Csv文件生成
        val dfCsv = spark.read.format("csv").option("header", true)
        .load("/Users/shirukai/Desktop/HollySys/Repository/sparkLearn/data/students.csv")
        dfCsv.show()
    
        //第四种：通过Json格式的RDD生成（弃用）
        val sc = spark.sparkContext
        import spark.implicits._
        val jsonRDD = sc.makeRDD(Array(
          "{\"name\":\"ming\",\"age\":20,\"phone\":15552211521}",
          "{\"name\":\"hong\", \"age\":19,\"phone\":13287994007}",
          "{\"name\":\"zhi\", \"age\":21,\"phone\":15552211523}"
        ))
    
        val jsonRddDf = spark.read.json(jsonRDD)
        jsonRddDf.show()
    
        //第五种：通过Json格式的DataSet生成
        val jsonDataSet = spark.createDataset(Array(
          "{\"name\":\"ming\",\"age\":20,\"phone\":15552211521}",
          "{\"name\":\"hong\", \"age\":19,\"phone\":13287994007}",
          "{\"name\":\"zhi\", \"age\":21,\"phone\":15552211523}"
        ))
        val jsonDataSetDf = spark.read.json(jsonDataSet)
    
        jsonDataSetDf.show()
    
        //第六种: 通过csv格式的DataSet生成
        val scvDataSet = spark.createDataset(Array(
          "ming,20,15552211521",
          "hong,19,13287994007",
          "zhi,21,15552211523"
        ))
        spark.read.csv(scvDataSet).toDF("name","age","phone").show()
    
        //第七种：动态创建schema
        val schema = StructType(List(
          StructField("name", StringType, true),
          StructField("age", IntegerType, true),
          StructField("phone", LongType, true)
        ))
        val dataList = new util.ArrayList[Row]()
        dataList.add(Row("ming",20,15552211521L))
        dataList.add(Row("hong",19,13287994007L))
        dataList.add(Row("zhi",21,15552211523L))
        spark.createDataFrame(dataList,schema).show()
    
        //第八种：读取数据库（mysql）
        val options = new util.HashMap[String,String]()
        options.put("url", "jdbc:mysql://localhost:3306/spark")
        options.put("driver","com.mysql.jdbc.Driver")
        options.put("user","root")
        options.put("password","hollysys")
        options.put("dbtable","user")
    
        spark.read.format("jdbc").options(options).load().show()
    
      }
    }

[Spark_DataFrame]: https://blog.csdn.net/shirukai/article/details/81085642