[SPARK-16284][SQL] Implement reflect SQL function

## What changes were proposed in this pull request?
This patch implements reflect SQL function, which can be used to invoke a Java method in SQL. Slightly different from Hive, this implementation requires the class name and the method name to be literals. This implementation also supports only a smaller number of data types, and requires the function to be static, as suggested by rxin in #13969.

java_method is an alias for reflect, so this should also resolve SPARK-16277.

## How was this patch tested?
Added expression unit tests and an end-to-end test.

Author: petermaxlee <petermaxlee@gmail.com>

Closes #14138 from petermaxlee/reflect-static.

2 files changed, 5 insertions, 25 deletions

diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
index 6f36abc4db..b8a75850b1 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
@@ -235,7 +235,10 @@ private[sql] class HiveSessionCatalog(
   // parse_url_tuple, posexplode, reflect2,
   // str_to_map, windowingtablefunction.
   private val hiveFunctions = Seq(
-    "hash", "java_method", "histogram_numeric",
-    "percentile", "percentile_approx", "reflect", "str_to_map"
+    "hash",
+    "histogram_numeric",
+    "percentile",
+    "percentile_approx",
+    "str_to_map"
   )
 }
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
index a43f0d0d7e..961d95c268 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
@@ -996,29 +996,6 @@ class SQLQuerySuite extends QueryTest with SQLTestUtils with TestHiveSingleton {
     checkAnswer(sql("SELECT CAST('775983671874188101' as BIGINT)"), Row(775983671874188101L))
   }
 
-  // `Math.exp(1.0)` has different result for different jdk version, so not use createQueryTest
-  test("udf_java_method") {
-    checkAnswer(sql(
-      """
-        |SELECT java_method("java.lang.String", "valueOf", 1),
-        |       java_method("java.lang.String", "isEmpty"),
-        |       java_method("java.lang.Math", "max", 2, 3),
-        |       java_method("java.lang.Math", "min", 2, 3),
-        |       java_method("java.lang.Math", "round", 2.5D),
-        |       java_method("java.lang.Math", "exp", 1.0D),
-        |       java_method("java.lang.Math", "floor", 1.9D)
-        |FROM src tablesample (1 rows)
-      """.stripMargin),
-      Row(
-        "1",
-        "true",
-        java.lang.Math.max(2, 3).toString,
-        java.lang.Math.min(2, 3).toString,
-        java.lang.Math.round(2.5).toString,
-        java.lang.Math.exp(1.0).toString,
-        java.lang.Math.floor(1.9).toString))
-  }
-
   test("dynamic partition value test") {
     try {
       sql("set hive.exec.dynamic.partition.mode=nonstrict")