RDD数据源

1、普通文本文件

sc.textFile("./dir/*.txt")

如果传递目录，则将目录下的所有文件读取作为RDD。文件路径支持通配符。

但是这样对于大量的小文件读取效率并不高，应该使用wholeTextFiles

def wholeTextFiles(path: String, minPartitions: Int = defaultMinPartitions): RDD[(String, String)])

返回值RDD[(String, String)]，其中Key是文件的名称，Value是文件的内容。

2、JDBC

Spark支持通过Java JDBC访问关系型数据库。需要使用JdbcRDD

代码演示

import java.sql.{Connection, DriverManager, PreparedStatement}
import org.apache.spark.rdd.{JdbcRDD, RDD}
import org.apache.spark.{SparkConf, SparkContext}

/**
  * Desc 演示使用Spark操作JDBC-API实现将数据存入到MySQL并读取出来
  */
object JDBCDataSourceTest {

  def main(args: Array[String]): Unit = {
    //1.创建SparkContext
    val config = new SparkConf().setAppName("JDBCDataSourceTest").setMaster("local[*]")
    val sc = new SparkContext(config)
    sc.setLogLevel("WARN")
    //2.插入数据
    val data: RDD[(String, Int)] = sc.parallelize(List(("jack", 18), ("tom", 19), ("rose", 20)))
    //调用foreachPartition针对每一个分区进行操作
    //data.foreachPartition(saveToMySQL)
    //3.读取数据
    def getConn():Connection={
DriverManager.getConnection("jdbc:mysql://192.168.119.131:3306/bigdata?characterEncoding=UTF-8", "root", "123456")
    }

    val studentRDD: JdbcRDD[(Int, String, Int)] = new JdbcRDD(sc,
      getConn,
   "select * from t_student where id >= ? and id <= ? ",
      4,
      6,
      2,
      rs => {
        val id: Int = rs.getInt("id")
        val name: String = rs.getString("name")
        val age: Int = rs.getInt("age")
        (id, name, age)
      }
    )
    println(studentRDD.collect().toBuffer)
 }
  /*
      CREATE TABLE `t_student` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `name` varchar(255) DEFAULT NULL,
      `age` int(11) DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;
   */
  def saveToMySQL(partitionData:Iterator[(String, Int)] ):Unit = {
    //将数据存入到MySQL
    //获取连接
    val conn: Connection = DriverManager.getConnection("jdbc:mysql://192.168.119.131:3306/bigdata?characterEncoding=UTF-8", "root", "123456")
    partitionData.foreach(data=>{
      //将每一条数据存入到MySQL
      val sql = "INSERT INTO `t_student` (`id`, `name`, `age`) VALUES (NULL, ?, ?);"
      val ps: PreparedStatement = conn.prepareStatement(sql)
      ps.setString(1,data._1)
      ps.setInt(2,data._2)
      ps.execute()//preparedStatement.addBatch()
    })

//ps.executeBatch()
    conn.close()
  }
}

3、 HadoopAPI

https://blog.csdn.net/leen0304/article/details/78854530

Spark的整个生态系统与Hadoop是完全兼容的，所以对于Hadoop所支持的文件类型或者数据库类型，Spark也同样支持。

HadoopRDD、newAPIHadoopRDD、saveAsHadoopFile、saveAsNewAPIHadoopFile 是底层API

其他的API接口都是为了方便最终的Spark程序开发者而设置的，是这两个接口的高效实现版本.

 

 4、SequenceFile文件

SequenceFile文件是Hadoop用来存储二进制形式的key-value对而设计的一种平面文件(Flat File)。

https://blog.csdn.net/bitcarmanlee/article/details/78111289

读sc.sequenceFile[ keyClass, valueClass](path)

写RDD.saveAsSequenceFile(path)

要求键和值能够自动转为Writable类型。

5、对象文件

对象文件是将对象序列化后保存的文件

读sc.objectFile[k,v](path) //因为是序列化所以要指定类型

写RDD.saveAsObjectFile()

6、HBase

由于 org.apache.hadoop.hbase.mapreduce.TableInputFormat 类的实现，Spark 可以通过Hadoop输入格式访问HBase。

这个输入格式会返回键值对数据，

其中键的类型为org. apache.hadoop.hbase.io.ImmutableBytesWritable，

而值的类型为org.apache.hadoop.hbase.client.Result。

https://github.com/teeyog/blog/issues/22

7、扩展阅读

import org.apache.hadoop.io.{LongWritable, Text}
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat
import org.apache.spark.rdd.RDD
import org.apache.spark.{SparkConf, SparkContext}

object DataSourceTest {
  def main(args: Array[String]): Unit = {
    val config = new SparkConf().setAppName("DataSourceTest").setMaster("local[*]")
    val sc = new SparkContext(config)
    sc.setLogLevel("WARN")

    System.setProperty("HADOOP_USER_NAME", "root")

    //1.HadoopAPI
    println("HadoopAPI")
    val dataRDD = sc.parallelize(Array((1,"hadoop"), (2,"hive"), (3,"spark")))

    dataRDD.saveAsNewAPIHadoopFile("hdfs://node01:8020/spark_hadoop/",
      classOf[LongWritable],
      classOf[Text],
      classOf[TextOutputFormat[LongWritable, Text]])

    val inputRDD: RDD[(LongWritable, Text)] = sc.newAPIHadoopFile(
      "hdfs://node01:8020/spark_hadoop/*", 
      classOf[TextInputFormat],
      classOf[LongWritable],
      classOf[Text],
      conf = sc.hadoopConfiguration
    )
    inputRDD.map(_._2.toString).foreach(println)

    //2.读取小文件
    println("读取小文件")
    val filesRDD: RDD[(String, String)] = sc.wholeTextFiles("D:\\data\\spark\\files", minPartitions = 3)
    val linesRDD: RDD[String] = filesRDD.flatMap(_._2.split("\\r\\n"))
    val wordsRDD: RDD[String] = linesRDD.flatMap(_.split(" "))
    wordsRDD.map((_, 1)).reduceByKey(_ + _).collect().foreach(println)

    //3.操作SequenceFile
    println("SequenceFile")
    val dataRDD2: RDD[(Int, String)] = sc.parallelize(List((2, "aa"), (3, "bb"), (4, "cc"), (5, "dd"), (6, "ee")))
    dataRDD2.saveAsSequenceFile("D:\\data\\spark\\SequenceFile")
    val sdata: RDD[(Int, String)] = sc.sequenceFile[Int, String]("D:\\data\\spark\\SequenceFile\\*")
    sdata.collect().foreach(println)

    //4.操作ObjectFile
    println("ObjectFile")
    val dataRDD3 = sc.parallelize(List((2, "aa"), (3, "bb"), (4, "cc"), (5, "dd"), (6, "ee")))
    dataRDD3.saveAsObjectFile("D:\\data\\spark\\ObjectFile")
    val objRDD = sc.objectFile[(Int, String)]("D:\\data\\spark\\ObjectFile\\*")
    objRDD.collect().foreach(println)

    sc.stop()
  }
}

 

import org.apache.hadoop.hbase.client.{HBaseAdmin, Put, Result}
import org.apache.hadoop.hbase.io.ImmutableBytesWritable
import org.apache.hadoop.hbase.{HBaseConfiguration, HColumnDescriptor, HTableDescriptor, TableName}
import org.apache.hadoop.hbase.mapred.TableOutputFormat
import org.apache.hadoop.hbase.mapreduce.TableInputFormat
import org.apache.hadoop.hbase.util.Bytes
import org.apache.hadoop.mapred.JobConf
import org.apache.spark.rdd.RDD
import org.apache.spark.{SparkConf, SparkContext}

object DataSourceTest2 {
  def main(args: Array[String]): Unit = {
    val config = new SparkConf().setAppName("DataSourceTest").setMaster("local[*]")
    val sc = new SparkContext(config)
    sc.setLogLevel("WARN")

    val conf = HBaseConfiguration.create()
    conf.set("hbase.zookeeper.quorum", "node01:2181,node02:2181,node03:2181")

    val fruitTable = TableName.valueOf("fruit")
    val tableDescr = new HTableDescriptor(fruitTable)
    tableDescr.addFamily(new HColumnDescriptor("info".getBytes))

    val admin = new HBaseAdmin(conf)
    if (admin.tableExists(fruitTable)) {
      admin.disableTable(fruitTable)
      admin.deleteTable(fruitTable)
    }
    admin.createTable(tableDescr)

    def convert(triple: (String, String, String)) = {
      val put = new Put(Bytes.toBytes(triple._1))
      put.addImmutable(Bytes.toBytes("info"), Bytes.toBytes("name"), Bytes.toBytes(triple._2))
      put.addImmutable(Bytes.toBytes("info"), Bytes.toBytes("price"), Bytes.toBytes(triple._3))
      (new ImmutableBytesWritable, put)
    }
    val dataRDD: RDD[(String, String, String)] = sc.parallelize(List(("1","apple","11"), ("2","banana","12"), ("3","pear","13")))
    val targetRDD: RDD[(ImmutableBytesWritable, Put)] = dataRDD.map(convert)

    val jobConf = new JobConf(conf)
    jobConf.setOutputFormat(classOf[TableOutputFormat])
    jobConf.set(TableOutputFormat.OUTPUT_TABLE, "fruit")

    //写入数据
    targetRDD.saveAsHadoopDataset(jobConf)
    println("写入数据成功")

    //读取数据
    conf.set(TableInputFormat.INPUT_TABLE, "fruit")
    val hbaseRDD: RDD[(ImmutableBytesWritable, Result)] = sc.newAPIHadoopRDD(conf, classOf[TableInputFormat],
      classOf[org.apache.hadoop.hbase.io.ImmutableBytesWritable],
      classOf[org.apache.hadoop.hbase.client.Result])

    val count: Long = hbaseRDD.count()
    println("hBaseRDD RDD Count:"+ count)
    hbaseRDD.foreach {
      case (_, result) =>
        val key = Bytes.toString(result.getRow)
        val name = Bytes.toString(result.getValue("info".getBytes, "name".getBytes))
        val color = Bytes.toString(result.getValue("info".getBytes, "price".getBytes))
        println("Row key:" + key + " Name:" + name + " Color:" + color)
    }
    sc.stop()
  }
}