如何在Spark中将多个sql函数包装成一个UDF？

import org.apache.spark.sql.expressions.UserDefinedFunction
import org.apache.spark.sql.functions._
import org.apache.spark.sql.types._

val concatAndUpper: UserDefinedFunction = udf((str1: String, str2: String) => {
  val concatStr = str1 + str2
  concatStr.toUpperCase()
})

val df = spark.createDataFrame(Seq(("hello", "world"), ("foo", "bar")))
  .toDF("col1", "col2")

val resultDf = df.withColumn("concat_upper", concatAndUpper(col("col1"), col("col2")))