sparkSQL

1.spark SQL简介

官网：http://spark.apache.org/

Spark SQL是Spark用来处理结构化数据的一个模块，它提供了一个编程对象，叫DataFrame，并且作为分布式SQL查询引擎的作用

 

2.为什么要学习spark SQL

2.1 我们已经学习了Hive，它是将Hive SQL转换成MapReduce然后提交到集群上执行，大大简化了编写MapReduce的程序的复杂性

2.2 MapReduce这种计算模型效率慢，代码繁碎，很多开发者都习惯使用sql，所以Spark SQL的应运而生，它是将Spark SQL转换成RDD，然后提交到集群执行，执行效率非常快，而且Spark SQL也支持从Hive中读取数据

3.spark SQL特点

3.1 集成 3.2 同意的访问方式 3.3hive集成 3.4标准连接

4.DataFrame的概念

（1）DataFram是组成命名列的数据集，它在概念上等同于关系数据库中的表，，但在底层具有更丰富的优化

（2）DataFrame可以从各种来源构建，列如：结构化数据文件， hive中的表，外部数据库或现有RDD

（3）DataFrame  API支持的语言有Scala，Java，Python和R

 

（4）从上图可以看出，DataFrame多了数据的结构信息，即schema（创建DataFrame的一种方式，后边详细介绍），RDD是分布式的 Java对象的集合

 

（5）DataFrame是分布式的Row对象的集合，DataFrame除了提供了比RDD更丰富的算子以外，更重要的特点是提升执行效率、减少数据读取以及执行计划的优化

 

 val row = lines.map ( _.split ( "," )).map ( tp => Row (  tp ( 0 ).toInt, tp ( 1 ), tp ( 2 ), tp ( 3 ), tp ( 4 ).toDouble, tp ( 5 ).toDouble, tp ( 6 ).toInt ))

 

 val frame: DataFrame = unit.map(tp=>{
      val splits=tp.split(" ")
      val id=splits(0).toInt
      val name=splits(1)
      val age=splits(2).toInt
      val result=splits(3).toInt
      (id,name,age,result)
    }).toDF("id","name","age","address")

 

5.DataSet的概念

 

（1）Dataset是数据的分布式集合，Dataset是在Spark 1.6中添加的一个新接口，是DataFrame之上更高一级的抽象

 

（2）Dataset提供了RDD的优点（强类型化，使用强大的lambda函数的能力）以及Spark SQL优化后的执行引擎的优点

 

（3）一个Dataset 可以从JVM对象构造，然后使用函数转换（map， flatMap，filter等）去操作

 

（4）Dataset API 支持Scala和Java， Python不支持Dataset API

6.创建DataFram

数据 emp.csv

7369,SMITH,CLERK,1980/12/17,1800,200,20
7499,ALLEN,SALESMAN,1981/2/20,1600,300,30
7521,WARD,SALESMAN,1981/2/22,1250,500,30
7566,JONES,MANAGER,1981/4/2,2975,900,20
7654,MARTIN,SALESMAN,1981/9/28,1250,1400,30
7698,BLAKE,MANAGER,1981/5/1,2850,122,30
7782,CLARK,MANAGER,1981/6/9,2450,344,10
7788,SCOTT,ANALYST,1987/4/19,3000,555,20
7839,KING,PRESIDENT,1981/11/17,5000,6666,10
7844,TURNER,SALESMAN,1981/9/8,1500,0,30
7876,ADAMS,CLERK,1987/5/23,1100,777,20
7900,JAMES,CLERK,1981/12/3,1950,888,30
7902,FORD,ANALYST,1981/12/3,3000,555,20
7934,MILLER,CLERK,1982/1/23,1300,57,10
7950,ZHAOYI,NANYOU,1980/1/1,1000,86,10

 

字段介绍：

1.编号 id
2.姓名 name
3.职业 job
4.日期 date
5.工资 sale
6.奖金 money
7.部门编号 number

 

方式一：spark2.0版本以前

 

package SparkSql
import org.apache.spark.sql.{DataFrame, SQLContext}
import org.apache.spark.{SparkConf, SparkContext}

object SqlDemo01 {
  def main(args: Array[String]): Unit = {
    val conf = new SparkConf ()
      .setAppName ( this.getClass.getSimpleName )
      .setMaster ( "local[1]" )
    val sc = new SparkContext ( conf )
    val sqlContext = new SQLContext ( sc )
    
    //获取dataset对象
    val lines:DataFrame = sqlContext.read.csv ( "E:\emp.csv" ).toDF("id","name","job","date","sale","money","number")
   //创建视图
    lines.createTempView ( "test01" )
    //书写sql语句
    sqlContext.sql("select id from test01").limit(10).show()

    sc.stop ()
  }
}

 

 

 方式二：spark 2.0之后

package SparkSql

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

object SqlDemo02 {
  def main(args: Array[String]): Unit = {
    val session = SparkSession.builder ().appName ( this.getClass.getSimpleName ).master ( "local[1]" ).getOrCreate ()
    //数据源
    val data: DataFrame = session.read.csv ( "E:\emp.csv" ).toDF ( "id", "name", "job", "date", "sale", "money", "number" )
    //创建视图
    data.createTempView ( "test01" )
    //书写sql语句
    session.sql ( "select * from test01" ).show ()
    session.stop ()

  }
}

 方式三：structType

package SparkSql


import org.apache.spark.rdd.RDD
import org.apache.spark.sql.types._
import org.apache.spark.sql.{DataFrame, Row, SparkSession}

object SqlDemo03 {
  def main(args: Array[String]): Unit = {
    val session = SparkSession.builder ().appName ( this.getClass.getSimpleName ).master ( "local[1]" ).getOrCreate ()

    //数据源
    val lines: RDD[String] = session.sparkContext.textFile ( "E:\emp.csv" )

    //创建row
    val row = lines.map ( tp => {
      val splits = tp.split ( "," )
      Row ( splits ( 0 ).toInt, splits ( 1 ), splits ( 2 ), splits ( 3 ), splits ( 4 ).toDouble, splits ( 5 ).toDouble, splits ( 6 ).toDouble )
    } )

    //创建schema
    val schme = StructType {
      List (
        StructField ( "id", IntegerType ),
        StructField ( "name", StringType ),
        StructField ( "job", StringType ),
        StructField ( "date", StringType ),
        StructField ( "sale", DoubleType ),
        StructField ( "money", DoubleType ),
        StructField ( "number", DoubleType ) )
    }


    val fram: DataFrame = session.createDataFrame ( row, schme )
    //创建视图
    fram.createTempView ( "test01" )

    //sql
    session.sql ( "select id,name from test01" ).show ()

    session.stop ()
  }
}

 方法四：样例类（case class 相当于表结构）

package SparkSql

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

object CaseDemo {
  /**
    * 样例类
    *
    * @param args
    */
  def main(args: Array[String]): Unit = {
    val session = SparkSession.builder ().appName ( this.getClass.getSimpleName ).master ( "local[1]" ).getOrCreate ()

    //读数据
    val unit = session.sparkContext.textFile ( "E:\emp.csv" ).map ( tp => tp.split ( "," ) )

    //如果RDD类型要转换为DataFrame,我们必须要导入隐士转换类
    import session.implicits._
    val frame: DataFrame = unit.map ( tp => Casewords ( tp ( 0 ).toInt, tp ( 1 ), tp ( 2 ), tp ( 3 ), tp ( 4 ).toDouble, tp ( 5 ).toDouble, tp ( 6 ).toDouble ) ).toDF ()
    frame.createTempView ( "test01" )

    session.sql (
      """
        |select *
        |from test01
      """.stripMargin
    ).show ()
  }
}

case class Casewords(
                      val id: Int,
                      val name: String,
                      val job: String,
                      val date: String,
                      val money: Double,
                      val sale: Double,
                      val number: Double) {


}

7.将数据保存到mysql

package SparkSql


import java.util.Properties

import org.apache.spark.rdd.RDD
import org.apache.spark.sql.types._
import org.apache.spark.sql.{DataFrame, Row, SparkSession}

  object SqlDemo03 {
    def main(args: Array[String]): Unit = {
      val session = SparkSession.builder ().appName ( this.getClass.getSimpleName ).master ( "local[*]" ).getOrCreate ()

      //数据源
      val lines: RDD[String] = session.sparkContext.textFile ( "E:\emp.csv" )

      //创建row
      val row = lines.map ( tp => {
        val splits = tp.split ( "," )
        Row ( splits ( 0 ).toInt, splits ( 1 ), splits ( 2 ), splits ( 3 ), splits ( 4 ).toDouble, splits ( 5 ).toDouble, splits ( 6 ).toDouble )
      } )

      //创建schema
      val schme = StructType {
        List (
          StructField ( "id", IntegerType ),
          StructField ( "name", StringType ),
          StructField ( "job", StringType ),
          StructField ( "date", StringType ),
          StructField ( "sale", DoubleType ),
          StructField ( "money", DoubleType ),
          StructField ( "number", DoubleType ) )
      }


      val fram: DataFrame = session.createDataFrame ( row, schme )
      //创建视图
      fram.createTempView ( "jobs" )

      //sql
   val resultDF:DataFrame=session.sql ( "select id,name from jobs" )

      //把数据保存到mysql表中
      //创建Properties对象你配置连接mysql的用户名和密码
      val pro=new Properties()
      pro.setProperty("user","root")
      pro.setProperty("password","123456")
      resultDF.write.jdbc("jdbc:mysql://localhost:3306/test1?characterEncoding=UTF-8&serverTimezone=GMT%2B8","jobs",pro)
//resultDF.write.mode(SaveMode.Append).jdbc("jdbc:mysql://localhost:3306/test1?characterEncoding=UTF-8&serverTimezone=GMT%2B8","jobs1",pro)
     //转json数据 coalesce ( 1 )创建分区 将所有json文件合成一个文件
     resultDF.coalesce ( 1 ).write.json ( "E:\jobs" )
      session.stop ()
    }


}