根据JSON创建对应的HIVE表
本文提供一种用SCALA把JSON串转换为HIVE表的方法，由于比较简单，只贴代码，不做解释。有问题可以留言探讨
package com.gabry.hive
import org.json4s._
import org.json4s.native.JsonMethods._
import scala.io.Source
class Json2Hive{
/**
* sealed abstract class JValue
*case object JNothing extends JValue // 'zero' for JValue
*case object JNull extends JValue
*case class JString(s: String) extends JValue
*case class JDouble(num: Double) extends JValue
*case class JDecimal(num: BigDecimal) extends JValue
*case class JInt(num: BigInt) extends JValue
*case class JBool(value: Boolean) extends JValue
*case class JObject(obj: List[JField]) extends JValue
*case class JArray(arr: List[JValue]) extends JValue
*type JField = (String, JValue)
*create table student_test(id INT, info struct< name:string,age:INT >)
*jsonString:{ "people_type":1,"people":{"person_id": 5,"test_count": 5,"para":{"name":"jack","age":6}}}
*/
private def fieldDelimiter(level:Int) = if ( level == 2 ) " " else ":"
private def decodeJson(jv: Any,level:Int,hql:StringBuilder) :Unit = {
jv match {
case js:JString => hql.append(fieldDelimiter(level)+"string,")
case jdo:JDouble => hql.append(fieldDelimiter(level)+"double,")
case jde:JDecimal => hql.append(fieldDelimiter(level)+"decimal,")
case ji:JInt => hql.append(fieldDelimiter(level)+"bigint,")
case jb:JBool => hql.append(fieldDelimiter(level)+"int,")
case jf:JField=>
hql.append(jf._1)
decodeJson(jf._2,level+1,hql)
case ja:JArray=>
hql.append(level + " struct<")
ja.arr.foreach(decodeJson(_,level+1,hql))
hql.append(">")
case jo:JObject=>
if (level !=0) hql.append(" struct<")
jo.obj.foreach(decodeJson(_,level+1,hql))
if ( hql.endsWith(",") ) hql.deleteCharAt(hql.length-1)
if (level !=0) hql.append(">,")
case JNull=> hql.append(fieldDelimiter(level)+"string,")
case _ =>println(jv)
}
}
def toHive(jsonStr:String,tableName:String):String = {
val jsonObj = parse(jsonStr)
val hql = new StringBuilder()
decodeJson(jsonObj,0,hql)
"create table %s ( %s )".format(tableName,hql.toString())
}
}
object Json2Hive{
val json2hive = new Json2Hive()
def main (args :Array[String]) : Unit = {
if ( args.length != 2 ) println("usage : json2hive jsonFile hiveTableName")
val jsonFile = args(0)
val hiveTableName = args(1)
//val jsonstr ="{ \"people_type\":0,\"people_num\":0.1,\"people\":{\"person_id\": 5,\"test_count\": 5,\"para\":{\"name\":\"jack\",\"age\":6}},\"gender\":1}"
//val jsonstr ="{ \"people_type\":0,\"object\":{\"f1\":1,\"f2\":1},\"gender\":1}"
/* 由于JSON串不容易用参数传递，故此处以json文件代替 */
val file = Source.fromFile(jsonFile,"UTF-8")
/* 将文件中的json串转换为对应的HIVE表 */
file.getLines().foreach(line=>println(json2hive.toHive(line.toString,hiveTableName)))
file.close()
}
}
以下是测试结果
create table example ( people_type bigint,people_num double,people struct<person_id:bigint,test_count:bigint,para struct<name:string,age:bigint>>,gender bigint )
