[SPARK-15031][EXAMPLE] Use SparkSession in examples

## What changes were proposed in this pull request?
Use `SparkSession` according to [SPARK-15031](https://issues.apache.org/jira/browse/SPARK-15031)

`MLLLIB` is not recommended to use now, so examples in `MLLIB` are ignored in this PR.
`StreamingContext` can not be directly obtained from `SparkSession`, so example in `Streaming` are ignored too.

cc andrewor14

## How was this patch tested?
manual tests with spark-submit

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #13164 from zhengruifeng/use_sparksession_ii.

1 files changed, 9 insertions, 3 deletions

diff --git a/examples/src/main/python/als.py b/examples/src/main/python/als.py
index f07020b503..81562e20a9 100755
--- a/examples/src/main/python/als.py
+++ b/examples/src/main/python/als.py
@@ -28,7 +28,7 @@ import sys
 import numpy as np
 from numpy.random import rand
 from numpy import matrix
-from pyspark import SparkContext
+from pyspark.sql import SparkSession
 
 LAMBDA = 0.01   # regularization
 np.random.seed(42)
@@ -62,7 +62,13 @@ if __name__ == "__main__":
       example. Please use pyspark.ml.recommendation.ALS for more
       conventional use.""", file=sys.stderr)
 
-    sc = SparkContext(appName="PythonALS")
+    spark = SparkSession\
+        .builder\
+        .appName("PythonALS")\
+        .getOrCreate()
+
+    sc = spark._sc
+
     M = int(sys.argv[1]) if len(sys.argv) > 1 else 100
     U = int(sys.argv[2]) if len(sys.argv) > 2 else 500
     F = int(sys.argv[3]) if len(sys.argv) > 3 else 10
@@ -99,4 +105,4 @@ if __name__ == "__main__":
         print("Iteration %d:" % i)
         print("\nRMSE: %5.4f\n" % error)
 
-    sc.stop()
+    spark.stop()